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Last Revision Date: 12/12/11
ETL-600 EYE & HEAD TRACKING LABORATORY
OPERATING INSTRUCTIONS
21 Cabot Road
Woburn, MA 01801
Tel. 781-932-1199
Fax: 781-932-1155
Email: [email protected]
ISCAN ETL-600 Instructions
TABLE OF CONTENTS i
Pages 1 - 2
Pages 3 - 5
Pages 7 - 18
Section 1: ETL-600 Components
Computer System ........................................................................................................... 1
Eye Imaging System ....................................................................................................... 2
Head Tracker Subsystem ............................................................................................... 2
Global View Camera Subsystem .................................................................................... 2
Laser Pointer Subsystem ............................................................................................... 2
Optional Computer Display Interface ............................................................................ 2
Section 2: ETL-600 Overview
Figure 2.1: ETL-600 Standard Configuration ........................................................... 3
Figure 2.2: Component Positioning ............................................................................ 4
Section 3: System Set Up
Part A: Setting Up the ETL-600 With the Tabletop Computer .................................... 7
Figure 3.1: ETL-600 Lab Set-up ................................................................................. 7
Figure 3.2: Computer Hook-up ................................................................................... 9
Part B: Setting Up the Global View Camera & Laser Pointer Subsystems................. 10
Figure 3.3: Global View & Laser Pointer Set-up ....................................................... 10
Part C: Setting Up the Global View Camera ................................................................. 11
Part D: Setting Up the Laser Pointer............................................................................. 11
Figure 3.4: Back of Pan/Tilt Unit ............................................................................... 12
Part E: Setting Up the Head Tracker Subsystem.......................................................... 13
Figure 3.5: Set-up of Head Tracker ............................................................................ 13
Part F: Hooking Up the Headset .................................................................................... 15
Figure 3.6: ETL-600 Headset...................................................................................... 15
Figure 3.7: Computer Chassis Front View................................................................. 17
Figure 3.8: Windows Start-up Screen & ETL-600 Icon............................................. 18
ISCAN ETL-600 Instructions
TABLE OF CONTENTS ii
Pages 19 - 28
Pages 29 - 36
Section 4: Obtaining Eye & Scene Images
Figure 4.1: LSW Main Window ..................................................................................19
Figure 4.2a: Enlarging the Eye Image ......................................................................20
Figure 4.2b: Enlarging the Scene Image ...................................................................21
Figure 4.3: Threshold Zero Settings for Eye 1 ..........................................................21
The Eye Image Landmarks ............................................................................................22
Figure 4.4: The Eye Imaging Camera Matrix & Eye Landmarks ...........................22
Figure 4.5: Eye Image With Matrix & Gate On ........................................................23
The Scene Imaging Camera Matrix ...............................................................................23
Figure 4.6: Scene Monitor Matrix & POR Indicator with Data Display .................24
Obtaining Good Eye Images With the Headset ............................................................24
Figure 4.7: Eye/Illuminator/Mirror Orientation .......................................................25
Figure 4.8: Image of the Eye, High-contrast Pupil/CR .............................................25
Figure 4.9: Tilting the Mirror In/Out ........................................................................26
Figure 4.10: Tilting the Eye Camera In/Out .............................................................27
Figure 4.11: Eye Image With Glasses .......................................................................27
Figure 4.12: Eyeglasses Adjustments ........................................................................28
Section 5: Tracking the Eye
Figure 5.1: Eye Tracking Controls Panel ..................................................................29
Part A: Threshold ............................................................................................................30
Figure 5.2: Pupil Threshold Adjustment ...................................................................30
Figure 5.3: Corneal Reflection Threshold Adjustment .............................................31
Figure 5.4: Corneal Reflection Crosshair with Threshold ........................................32
Figure 5.5: Pupil and CR Crosshairs On with Threshold Display Off ....................32
Figure 5.6: Good Tracking Eye Image with Threshold ............................................33
Figure 5.7: Eye Image Gate .......................................................................................34
Figure 5.8: Aux 1 Controls Panel ...............................................................................34
Adjustment of the Scene Camera ...................................................................................35
ISCAN ETL-600 Instructions
TABLE OF CONTENTS iii
Pages 37 - 48 Section 6: Calibrating the Eye to the Scene
Overview of Point-of-Regard Calibration Procedure ....................................................37
Overview of Eye Angle Calibration Procedure ..............................................................37
Point-of-Regard Calibration ...........................................................................................37
Setting Up the Calibration Targets ...............................................................................38
Figure 6.1: Calibration Procedure .............................................................................38
Checking the Eye & Scene Images ................................................................................39
The Point-of-Regard Calibration Procedure ..................................................................39
Figure 6.2: RK-630 POR Scene Image........................................................................39
Figure 6.3: Symbol of Point Of Regard ......................................................................39
Figure 6.4: POR Data Display ....................................................................................40
Figure 6.5: POR Calibration Control Panel with Large Scene Image .....................40
Figure 6.6: Center Calibration Point .........................................................................41
Figure 6.7: Upper Left Calibration Point ..................................................................42
Figure 6.8: Upper Right Calibration Point ...............................................................43
Figure 6.9: Lower Left Calibration ............................................................................43
Figure 6.10: Lower Right Calibration .......................................................................44
Figure 6.11a: POR Output Active After Calibration ................................................44
Figure 6.11b: POR Tracking Enabled After Calibration ..........................................45
Calibration Auxiliary Controls .......................................................................................45
Figure 6.12: POR AUX Panel Settings for Monocular Operation ............................45
Storing a Calibration Model ...........................................................................................46
Figure 6.13: LSW Window With the Save Selection ................................................46
Figure 6.14: Save Calibration File Name ..................................................................47
Recalling a Calibration Model ........................................................................................47
Figure 6.15: Open Calibration File ............................................................................48
Figure 6.16: POR Output Active ................................................................................48
ISCAN ETL-600 Instructions
TABLE OF CONTENTS iv
Pages 49 - 72 Section 7: Eye Angle Calibration
Part A: Mapping of the Planar Surfaces ........................................................................ 49
Figure 7.1: 3D Mapping of Multiple Planar Surfaces .............................................. 49
Figure 7.2a: Multiple Planar Surfaces (Viewed from Above) ................................... 50
Figure 7.2b: Multiple Planar Surfaces (Partial View) .............................................. 51
Figure 7.3: Environment Planes Layout Icon ........................................................... 52
Figure 7.4a: Environment Planes Layout Editor for Plane 1 .................................. 52
Figure 7.4b: Measurements to Establish the Relationship of
Magnetic Source to Plane 1 ........................................................... 53
Figure 7.5: Environment Planes Layout Editor for Planes 2 & 3 ............................ 54
Part B: Registration of Planar Surfaces with the Global View Scene Monitor ............ 55
Figure 7.6: Monitor Schematic .................................................................................. 55
Figure 7.7: Global View Monitor ............................................................................... 56
Figure 7.8: Video Display Unit Control Panel .......................................................... 56
Figure 7.9: Center Point Registration ....................................................................... 57
Figure 7.10: Upper Left Point Registration .............................................................. 57
Figure 7.11a: Upper Right, Lower Left, Lower Right Points Registration ............. 58
Figure 7.11b: Clearing the Active Item Box............................................................... 58
Figure 7.12a: Global View Image Display of Multi-Plane Area ............................... 59
Figure 7.12b: VDU Control Panels for Multiple Planes Registration ..................... 59
Figure 7.13: Matching Z Coordinates ........................................................................ 60
Part C: Verification of Head Vector Intersection with Planar Surfaces ...................... 62
Figure 7.14: Global View Scene Image Display ........................................................ 62
Figure 7.15: LSW Window with Mannequin Head Data .......................................... 63
Figure 7.16: Eye Angle Calibration Controls Panel ................................................. 64
Figure 7.17: ETL-600 Boresight in Center Plane 1 .................................................. 65
Figure 7.18: Movement of the Head Vector Intersection Indicator ......................... 66
Part D: Eye Angle Calibration ....................................................................................... 67
Figure 7.19: Boresight in Center Plane 1 .................................................................. 67
Figure 7.20: Eye Angle Calibration Center ............................................................... 68
Figure 7.21: Laser Pointer Inside Center of the Indicator ....................................... 68
Figure 7.22a: Left Calibration Point ......................................................................... 69
Figure 7.22b: Right, Top & Bottom Calibration Points ............................................ 70
Figure 7.23: Graph A in the LSW Window ............................................................... 71
Eye Sensor Measurements ............................................................................................. 71
Figure 7.24: AUX1 Tab & Panel ................................................................................ 71
Figure 7.25: Safety Glasses Headset, Two Views ..................................................... 72
ISCAN ETL-600 Instructions
TABLE OF CONTENTS v
Pages 73 - 80
Pages 81 - 100
Section 8: Graph Display Controls
Figure 8.1: Graph Control & Display Area ............................................................... 73
Graph Display Parameters Labels & Descriptions ....................................................... 75
Section 9: LSW Software Features and Functions
Part A: Blink Monitoring................................................................................................. 81
Figure 9.1: Blink Monitor Configuration Panel ........................................................ 82
Figure 9.2: Blink Controls Enabled ........................................................................... 82
Figure 9.3: Blink Control Panel ................................................................................. 83
Part B: ISCAN Analog Outputs ..................................................................................... 84
Selecting Analog Outputs ............................................................................................... 84
Figure 9.4: Analog Output Control Panel ................................................................. 84
Figure 9.5: Select Analog Output Parameters .......................................................... 84
Figure 9.6: Analog Output Parameters & Graph Displays ...................................... 85
Configuring the Analog Outputs .................................................................................... 86
Figure 9.7: Analog Inputs & Outputs Control Panel ................................................ 86
Part C: Serial I/O ............................................................................................................ 87
Example of How to Use Serial Port ............................................................................... 87
Figure 9.8: Serial I/O Configuration Panel ............................................................... 87
Figure 9.9: Serial Output Controls Panel ................................................................. 88
Part D: Digital I/O .......................................................................................................... 89
Figure 9.10: ISCAN Digital I/O Connector ............................................................... 89
Figure 9.11: Digital I/O Configuration Panel ........................................................... 90
Figure 9.12: Digital Output Controls Panel .............................................................. 90
Figure 9.13: Digital Output Bit Selection ................................................................. 91
Part E: Recording Data .................................................................................................. 92
Figure 9.14: Data Recording Control Panel .............................................................. 93
Figure 9.15: Data Recording Parameters Bank ........................................................ 93
Recording Configuration Panel ...................................................................................... 94
Figure 9.16: Recording Configuration Panel ............................................................. 94
Example of Recording and Reading Data ...................................................................... 96
Figure 9.17: Data Recording Controls Info ............................................................... 96
Figure 9.18: Save TDA Data in File .......................................................................... 97
Figure 9.19: Saving Data as Test.TDA ...................................................................... 97
Figure 9.20: Open WordPad ....................................................................................... 98
Figure 9.21: Test.TDA Data ....................................................................................... 99
ISCAN ETL-600 Instructions
TABLE OF CONTENTS vi
Pages 101 - 106
Pages 107 - 110
Pages 111 - 116
Pages 117 - 118
Section 10: Recording Data for Analysis by ISCAN’s PRZ Software
Figure 10.1: Loading VDU.H2A & VDU.V2A into Bank 1 .......................................101
Part A: Image Registration for PRZ ...............................................................................101
Figure 10.2: Image Registration, Upper Left ............................................................102
Figure 10.3: Defining the Anchor Points....................................................................102
Part B: Recording a Data Run .......................................................................................103
Figure 10.4: Start Recording ......................................................................................103
Figure 10.5: Quit Recording .......................................................................................103
Part C: Storing the Eye/Head Plane Intersection Data in a Fixation File ..................104
Figure 10.6: Select Save Fixation File .......................................................................104
Figure 10.7: Open Fixation File .................................................................................104
Figure 10.8: Identifying a Fixation File ....................................................................105
Figure 10.9: Saving a Fixation File ...........................................................................105
Section 11: PRZ Overview
Task Configuration .........................................................................................................107
Scope & Study Context ...................................................................................................107
Stimulus Images .............................................................................................................107
Master Registration Image ............................................................................................108
PRZ/DQW Workflow .......................................................................................................108
Figure 11.1: PRZ/DQW Workflow Diagram ..............................................................109
Figure 11.2: PRZ File Definitions Table ....................................................................110
Section 12: Saving & Retrieving Configuration Settings
Saving Definition Files ...................................................................................................111
Figure 12.1: Save LSW Settings ................................................................................111
Figure 12.2: Saving a Unique .def File ......................................................................112
Retrieving LSW Settings Via Definition Files ..............................................................112
Figure 12.3: Open LSW Settings in File Menu .........................................................112
Figure 12.4: Selecting a Saved .def File ....................................................................113
Factory Definition File ...................................................................................................113
Figure 12.5: Factory .def ETL-600 Settings ..............................................................114
Section 13: IR Irradiance & Safety
ISCAN ETL-600 Instructions
TABLE OF CONTENTS vii
Pages 119 - 128 Section 14: ETL-600 Appendices
Appendix A: Single Plane/Computer Screen Stimulus Operation .......................119
Figure A.1: ETL-600 Single Plane Configuration .....................................................119
Part A: Setting Up the Single Plane/Computer Monitor Connections .........................120
Figure A.2: ETL-600 Computer Hook-up ..................................................................120
Part B: Changing the Title of the Monitor to VDU Monitor ........................................121
Figure A.3: Changing the Name of the Monitor .......................................................121
Part C: Entering the Planar Surface Coordinates ........................................................121
Part D: Alignment of the VDU Display Borders ...........................................................122
Figure A.4: VDU Controls Panel ...............................................................................122
Figure A.5: Selecting Left Border for Alignment ......................................................122
Figure A.6: Selecting Right, Top, & Bottom Borders for Alignment .......................123
Part E: Verification of the Head Intersection ...............................................................124
Part F: Eye Angle Calibration ........................................................................................124
Appendix B: Additional ISCAN Head-mounted Units .............................................125
Figure B.1: Headband-mounted Monocular System ................................................125
Appendix C: Serial I/O ....................................................................................................127
Auxiliary Serial Output Formats ...................................................................................127
ISCAN Serial Output Format (ASCII) ..........................................................................127
Binary Output Format ...................................................................................................127
Remote Serial Controls ...................................................................................................128
Remote Serial Command Bytes .....................................................................................128
ISCAN ETL-600 Instructions
Section 1: ETL-600 Components 1
Section 1: ETL-600 Components
The ISCAN ETL-600 Head & Eye Tracking Laboratory contains all components necessary
to measure head and eye movements of a human subject and to calculate point-of-gaze and
target plane intersection coordinates with respect to the working environment.
The ETL-600 components include the following subsystems:
1. Personal computer chassis with the following accessories:
• AC line cord for PC operation at either 120VAC or 230VAC
• 17” LCD monitor
• AC line cord for monitor operation at either 120VAC or 230VAC
• Keyboard
• Mouse
• 6 1’ BNC cables
• 6’ phono cable
• Phono/BNC adaptor
The PC also contains the follow circuit cards and software:
Component
SG-100 camera control card
RK-826PCI monocular eye
tracker
RK-630PCI calibration
subsystem
Video Display Unit (VDU) PCI
card
3-channel video display card
3 serial ports
LSW Line of Sight (LOS) and
Target Intersection software
PRZ Analysis software
Function
Supplies power to head-mounted cameras and
illuminator; outputs eye and scene video channels
Tracks eye position from head-mounted eye imaging
camera
Calculates real-time point of gaze; superimposes gaze
point over scene from head-mounted scene imaging
camera
Accepts video input from a stand-alone global field of
view camera or a VGA/NTSC converter from a host
PC monitor display
Displays the eye, scene and VDU images in real time
on the PC monitor
One port interfaces with the magnetic head tracker;
two ports used for input/output data transfer from
the ETL-600
Allows the system operator to monitor eye and head
tracker functions and calibrate the subject to
generate eye/head line-of-sight vectors with respect
to their working environment; records and saves eye
movement and head movement data for analysis
Allows the operator to analyze the head/eye data for
quantitative representations of fixation times, pupil
size, blinks, and scan path information with respect
to planar surfaces in the working environment
ISCAN ETL-600 Instructions
Section 1: ETL-600 Components 2
2. Head-mounted Eye/Scene Imaging System, comprised of the following items:
• Miniature eye camera
• Infrared illuminator
• Scene camera
• Magnetic sensor (20’ range, for head tracking)
• Plastic safety goggle, headband or spectacles frame
• 15’ SG-100 camera control card connecting cable (also called the umbilical cable)
3. Head Tracker Subsystem:
• Patriot/FasTrak/Liberty Magnetic Head Tracker Control Unit
• 20’ Magnetic source
• Floor mount for source
• Power supply for magnetic tracker, 120VAC or 230VAC
• Serial interface cable (for PC serial port 1 interface)
• Tape measure
4. Global View Camera Subsystem
• Color video camera
• 12VDC camera power supply
• AC line cord for 120VAC or 230VAC
• Floor tripod camera mount
• 25’ BNC connecting cable (for VDU input)
5. Laser Pointer Subsystem
• 2-axis motorized mount with laser pointer
• 25’ cable with hand controller for mount
• 6VDC power supply
• AC line cord for power supply, 120VAC or 230VAC
• Tripod floor mount for laser pointer mount
6. Optional Computer Display Interface
• VGA-to-NTSC converter
• +12VDC power supply for VGA-to-NTSC converter
• AC line cord for VGA-to-NTSC converter operation at either 120VAC or 230VAC
ISCAN ETL-600 Instructions
Section 2: ETL-600 Overview
3
Section 2: ETL-600 Overview
The ISCAN ETL-600 Eye & Head Tracking Laboratory tracks the eye and head movement
of a human subject in real time and generates point-of-gaze data with respect to the head-
mounted scene camera. The ETL-600 also calculates line-of-sight vector data using
combined eye and head position and displays the intersection point of the line-of-sight
vector as an indicator superimposed over a global view scene display, with up to 20 planar
surfaces in the subject’s surrounding environment.
The subject may be seated or standing, wearing the head-mounted eye and scene cameras
and the head tracker sensor on a lightweight plastic head mount. The magnetic source and
sensor units are coupled via 20’ cables to the magnetic head tracker unit, and the eye and
scene cameras on the headset are coupled to the eye tracking personal computer via a 15’
cable. The magnetic head tracker unit is coupled to the eye tracking computer via a serial
data cable that carries the real-time six-degree-of-freedom head position data. The
magnetic source is mounted on a floor tripod and is generally placed behind the subject
with the subject staying within two feet in the front hemisphere of the source.
A schematic of a typical set-up is shown below:
Figure 2.1: ISCAN ETL-600 Standard Configuration
ISCAN ETL-600 Instructions
Section 2: ETL-600 Overview
4
Planar surfaces surrounding the subject must be mapped with respect to the magnetic
source. The magnetic head tracker calculates the position in X, Y, and Z and Azimuth,
Elevation, and Roll of the head-mounted sensor with respect to the center of the source.
These measurements are in inches for X, Y and Z displacement of the sensor from the
source and in degrees of angle for the orientation of the sensor with respect to the source.
Figure 2.2: Component Positioning
The planar surfaces that are of interest to the operator must be entered into the line-of-
sight software as coordinate groups, defining a plane, with respect to the 0, 0, 0 origin of
the source. This mapping of planar surfaces may be used for multiple monitors, flat
surfaces, screens or areas of interest in a 360º arc around the subject.
Once the coordinate mapping of the surfaces has been completed, a rapid calibration
procedure is performed, using an operator-controlled laser pointer in conjunction with the
global view camera display. The operator instructs the subject to sequentially look at a
pattern of five calibration points within the field of view. After the calibration procedure,
the system outputs plane number and the X, Y location of the subject’s combined eye/head
line of sight within each plane in real time. The data shows precisely the point the subject
is looking at in the 3-dimensional workspace. The data may be stored for analysis or used
as a real-time control signal for man/machine interface and control experiments.
ISCAN ETL-600 Instructions
Section 2: ETL-600 Overview
5
As an integrated eye/head tracking system, the ETL-600 is comprised of several discreet
functional parts. An outline of the steps necessary to successfully set up and operate the
system, and where each step can be found, is as follows:
! Setting up the system components and hooking up the cables (Section 3)
! Tracking the eye using the headset (Sections 4 and 5)
! Calibrating the eye data to the head-mounted scene camera (point of regard
calibration) (Section 6)
! Defining the planar surfaces surrounding the subject (Section 7)
! Registering the defined planar surfaces to the global view image of the subject’s
environment (Section 7)
! Verifying the head position data (Section 7)
! Calibrating the eye and head data (eye angle calibration) with respect to the planar
surfaces (Section 7)
! Recording the eye and head data (Section 7)
! Recording the eye and head tracking data for input to the PRZ advanced point-of-
regard analysis software (Section 10)
ISCAN ETL-600 Instructions
Section 2: ETL-600 Overview
6
PAGE INTENTIONALLY LEFT BLANK
ISCAN ETL-600 Instructions
Section 3: ETL-600 Set-up
7
Section 3: Setting up the ETL-600
Part A: Setting Up the ETL-600 With the Tabletop Computer
After unpacking all the system components as listed in Section 1, please note that all
connectors are labeled so as to exactly match each end, cable to component. The following
step-by-step directions describe how to set up all the components as shown in Figure 3.1
below.
Figure 3.1: ETL-600 Lab Set Up
ISCAN ETL-600 Instructions
Section 3: ETL-600 Set-up
8
Hooking up the PC chassis and Monitor:
! Connect the VGA cable between the 17"PC LCD monitor and the VGA output port of
the computer chassis labeled "CONNECT PC VGA MONITOR HERE ONLY"
! Connect the AC line cord to the 17" PC VGA monitor.
! Connect the mouse to an open USB port in the back of the eye tracker PC chassis.
! Connect the keyboard to an open USB port in the back of the eye tracker PC chassis.
! Connect the AC line cord to the power receptacle on the back of the eye tracker PC
chassis.
! Plug in the 17" PC VGA monitor line cord to an AC power source.
! Plug in the eye tracker PC power cord to an AC line source.
! Using the 1' BNC cable labeled "RK-826PCI VIDEO OUT" on one end and "EYE
MONITOR" on the other, connect the BNC output of the RK-826PCI Video Out
connector to the input of the Eye Monitor on the 3 channel video display card.
! Using the 1' BNC cable labeled "RK-630PCI OPER VIDEO OUT" on one and "SCENE
MONITOR" on the other, connect the BNC Operator Output on the RK-630PCI
Autocalibrator card to the input of the Scene Monitor on the 3 channel video display
card.
! Using the 1' BNC cable labeled "VDU2PCI OPER VIDEO OUT" on one end and "VDU
MONITOR VIDEO IN" on the other, connect the BNC output of the VDU2 Operator
Output to the input of the VDU Monitor on the 3-channel video display card.
! Using the 1' BNC cable labeled "EYE CAMERA VIDEO OUT" on one end and "RK-
826PCI VIDEO IN" on the other, connect the BNC output of the Eye Camera Output
on the bottom slot SG-100 card to the input of the RK-826PCI eye tracker card directly
above it.
! Using the 1' BNC cable labeled "SCENE CAMERA VIDEO OUT" on one end and "RK-
630PCI SCENE VIDEO IN" on the other, connect the BNC output of the Scene
Camera Output on the bottom slot’s SG-100 to the Scene Video Input of the RK-
630PCI Autocalibrator card in the third slot of the computer.
! Using the 25' BNC cable labeled "VDU2 SCENE VIDEO IN" one end and "GLOBAL
VIEW OUT" on the other, connect the VDU2 Scene Video Input cable to the VDU card
in the fifth slot up from the bottom in the PC. The other end of the cable will be
connected to the output of the global view camera described in the set up following.
! Connect the serial cable to the COM 1 serial port of the PC, labeled "HEAD TRACKER
SERIAL INPUT". The other end of the serial cable will be connected to the RS-232
output on the head tracker control unit.
! Connect the Eye Imager cable to the input on the SG-100 card in the bottom PCI slot
in the PC, labeled "EYE IMAGER IN". A yellow label also reads "CONNECT EYE
IMAGER HERE ONLY".
ISCAN ETL-600 Instructions
Section 3: ETL-600 Set-up
9
A schematic diagram showing all the eye tracker PC chassis connections are shown in
Figure 3.2 below.
Figure 3.2: Diagram of Back of Computer with All Cables Hooked Up
ISCAN ETL-600 Instructions
Section 3: ETL-600 Set-up
10
Part B: Setting Up the Global View Camera and Laser Pointer Systems
The global view camera must be set up to view the operational field of view of the subject.
The global view imagery, in conjunction with the laser pointer subsystem is used to
quickly calibrate the subject to one of the planar surfaces within the field of view.
The global view camera should be mounted on a tripod and positioned so that the system
operator can see a clear in focus image of the subject's working environment. For example,
if the subject is viewing a display of two computer monitors, the field of view of the global
camera should be adjusted to clearly encompass the active areas of both monitors. The
front surface of the monitor that is most directly in front of and normal to the subject will
be designated Plane 1. The laser pointer subsystem should also be positioned so that the
laser can be positioned by the system operator to cover the entire surface of the Plane 1.
Figure 3.3 shows the relative positions of the global view camera and laser pointer with
respect to a subject viewing three planar surfaces.
Figure 3.3: Schematic of Global View and Laser Pointer Set Up
ISCAN ETL-600 Instructions
Section 3: ETL-600 Set-up
11
Part C: Setting up the Global View Camera
! Attach the global view scene camera to the global view tripod assembly.
! Plug in the global view scene camera power supply to the back of the global view
camera. Plug in the camera power supply into a wall AC source.
! Connect the end of the 25' BNC cable labeled "GLOBAL VIEW CAMERA OUT" to the
video output connector on the back of the global view camera. The other end of the 25'
BNC cable has already been attached to the VDU2 Scene Video Input on the back of
the eye tracker PC.
Part D: Setting up the Laser Pointer
! Attach the pan/tilt unit containing the laser pointer to the Laser Pointer Tripod.
! Connect the +6VDC power supply to the input connector on the front side of the
pan/tilt unit labeled "PTU POWER IN". Plug in the +6VDC power supply into a wall
AC outlet. Turn on the power switch on the back of the pan/tilt unit. The power switch
is the rightmost of the two switches on the back panel of the pan/tilt unit. The left
switch should be set at 0 degrees, all the way down, and the right power switch should
be set in the middle position at the M position. The green POWER ON LED will be
illuminated when the pan tilt is powered up. Figure 3.4 shows photos of the Laser
Pointer set up, and a schematic of the back of the pan/tilt unit.
ISCAN ETL-600 Instructions
Section 3: ETL-600 Set-up
12
Figure 3.4: Back of Pan/Tilt Unit
! Plug in the pan/tilt hand controller on its 25' cable. Position the hand controller so the
system operator can easily move the position of the laser pointer while watching the
ISCAN eye tracker LSW software control screen.
! Turn on the laser pointer by pushing the pointer body into the cylindrical tube it is
mounted on. The pushbutton will be pushed on and the laser pointer output should be
visible within the work area of the subject. Make sure that the tripod head is
positioned so that the range of the pan and tilt unit, when used with the hand
controller, covers the surface of the primary surface (plane1) that will be used for
subject calibration.
ISCAN ETL-600 Instructions
Section 3: ETL-600 Set-up
13
Part E: Setting up the Head Tracker Subsystem
The ETL-600 is provided with one of three models of Polhemus Head Tracker Systems.
The most common version of the head tracker is the Patriot, a single sensor, 60Hz, six
degree of freedom magnetic head tracker. The Patriot Magnetic source is a 2" cube that
contains the transmitter coil, and the sensor head tracker unit is mounted onto the ISCAN
headset along with the miniature eye and scene cameras.
The magnetic source is normally mounted onto a floor tripod that should be positioned
behind the subject's head at about the same height as the sensor. The source has a bubble
level attached to it and the tripod should be adjusted so the bubble level is centered. Keep
the subject within approximately 1' of the magnetic source and operate the source and
sensor away from any ferrous or metal objects that can interfere with the magnetic field.
A photo of the source and sensor set up is shown in Figure 3.5
Figure 3.5: Set-up of Head Tracker
! Connect the thick gray head tracker source cable to the front panel connector of the
Patriot labeled "SOURCE".
! Connect the thin gray head tracker sensor cable coming from the ISCAN headgear to
the front panel connector on the Patriot labeled "SENSOR 1".
! Connect the AC line cord to the Polhemus +5 power supply.
ISCAN ETL-600 Instructions
Section 3: ETL-600 Set-up
14
! Plug in the +5VDC output of the Polhemus power supply to the connector on the back
panel of the Patriot labeled "DC IN". Plug in the AC line cord of the power supply to
an AC wall source. The Polhemus power supply supports a 120VAC - 230VAC input
range.
! Connect the serial cable to the back panel connector on the Patriot labeled "RS-232".
The other end of the serial cable has already been connected to the COM 1 head
tracker serial input on the eye tracking computer.
! Look at the back panel of the Patriot and make sure that all the DIP switches in the
"CONFIG" panel are all in the OFF or DOWN position.
The head tracker subsystem is now completely assembled and ready to go.
ISCAN ETL-600 Instructions
Section 3: ETL-600 Set-up
15
Part F: Hooking Up Headset
The following directions describe the step-by-step procedure for connecting the headset
and head tracker unit to the eye tracker computer.
The headset is comprised of a miniature eye imaging camera and a miniature scene
imaging camera, all mounted onto a plastic safety glasses frame.
Figure 3.6: ETL-600 Headset
The safety glasses are designed to fit over most normal spectacle frames. The eye camera
views the subject's eye via a plastic hot mirror that passes visible light but reflects a near
infrared image of the eyes into the cameras. The eye is illuminated by a low-level near
ISCAN ETL-600 Instructions
Section 3: ETL-600 Set-up
16
infrared light emitting diode (LED) and the LED is positioned next to the eye camera to
properly reflect the light off of the plastic mirror to illuminate the eye area.
The eye camera is mounted on a moveable post that allows it to be twisted up and down.
The plastic mirror is mounted on a thin adjustable rod so it can also be tilted up and down
to image the eye at its optimal angle of view.
There is also a lanyard strap in the back of the safety glasses to comfortably secure the
headset to the head. Do not remove this strap. At the very least, it prevents the headset
from falling off the subject's head and becoming damaged.
! Initially have a person other than the system operator put the headset on. Secure the
head set to the subject with the strap on the back of the head. Plug in the thin black
cable connector labeled "EYE CAMERA OUT", the other end of this cable has already
been connected to the SG-100 card in the eye tracker PC. Attach the silver clip on the
cable end to the subject's clothing to act as a strain relief for the headset.
At this point all the system components are hooked up and the ETL-600 system is ready
for initial operation.
If the system is provided with the tower PC chassis, please note that the computer chassis
is normally configured for 120VAC power input for use in North America and Japan. If the
system is shipped to the rest of Asia or to Europe, the power supplies are configured for
230VAC and a label above the power receptacle will indicate this. If it is necessary to
switch the PC for 120VAC or 230VAC input, unsnap the front cover and push up the
voltage selection switch as shown in Figure 3.7 below.
ISCAN ETL-600 Instructions
Section 3: ETL-600 Set-up
17
Figure 3.7: Computer Chassis Front View and With Front Panel Removed
To power up the tabletop PC, press the power button on the top front of the PC chassis as
shown in Figure 3.7 above. The power switch for the 17" PC VGA LCD monitor is located
on the front of the monitor.
WARNING: Do not apply 230VAC to the PC chassis if the voltage selection
switch reads 110V. This will result in damage to the computer power supply
and possibly the eye tracking circuit cards.
ISCAN ETL-600 Instructions
Section 3: ETL-600 Set-up
18
! Turn on the tabletop PC and monitor.
! Turn on the head tracker. The power switch for the Patriot is located on the back
panel of the control unit, next to the power supply input connector.
! Make sure that the global view camera is powered up.
! Make sure that the laser pointer is on and that the pan/tilt unit is moving in response
to commands from the pan/tilt hand controller.
The eye tracker PC will start up and after a brief interval, a Windows 7 screen will appear
that should look something like that shown in Figure 3.8 below.
Figure 3.8: Win 7 Start Up Screen With ETL-600 Icon
Note that there is an ETL-600 icon on the Windows 7 start up screen. Double clicking on
this icon opens the ISCAN LSW Data Acquisition Software.
ISCAN ETL-600 Instructions
Section 4: Obtaining Eye & Scene Images
19
Section 4: Obtaining Eye and Scene Images
With the ISCAN LSW software main window now open, and a subject wearing the
headgear, this section will discuss the tools and techniques involved in obtaining clear, in-
focus images of the eye and adjusting the scene camera.
Figure 4.1 below shows the ISCAN LSW window, configured for monocular eye tracking.
The eye tracking control panel for the eye is located in the upper left quadrant of the LSW
control window and is labeled "1" in Figure 4.1.
Figure 4.1: LSW Main Window
ISCAN ETL-600 Instructions
Section 4: Obtaining Eye & Scene Images
20
Note that there is a control panel for the eye labeled "EYE 1." The ETL-600 is normally set
up with Eye 1 as the subject's left eye. At the bottom of the LSW window are panels
labeled "EYE MONITOR"(5), "SCENE MONITOR"(6) and "GLOBAL VIEW
MONITOR"(7). The video signal from the head-mounted eye camera runs through the RK-
826PCI Eye Tracker card and is displayed on the eye monitor. The video from the head-
mounted scene camera runs through the RK-630PCI Autocalibrator card and is displayed
on the scene monitor.
In the upper right hand corner of each monitor display there is a small click box. Clicking
on this box will expand the monitor image to fill in the area of the graph display controls
(9). In addition, clicking on the monitor expansion box will automatically bring up the
associated control panel for that enlarged image.
For example, clicking on the Eye Monitor box will expand the eye image coming out of the
RK-826PCI 2 and also bring to the forefront the Eye 1 control panel. If the Scene Monitor
is expanded, a calibration control panel will automatically appear in the Auxiliary
Controls Panel area (3). Figure 4.2 shows the corresponding selection of the eye and scene
images with their associated control panels.
Figure 4.2A: Enlarging the Eye Image
ISCAN ETL-600 Instructions
Section 4: Obtaining Eye & Scene Images
21
Figure 4.2B: Enlarging the Scene Image
Set the pupil and corneal reflection threshold levels to zero, for Eye 1. (There will be a
detailed discussion of the threshold functions later in the manual.) Click on the Eye 1
panel tab and use the mouse to drag the both the pupil and corneal reflection threshold
sliders to the lowest point of the slider controls. The number zero should be seen in both
boxes below the sliders, as shown in Figure 4.3 below.
Figure 4.3: Threshold Zero Settings for Eye 1
ISCAN ETL-600 Instructions
Section 4: Obtaining Eye & Scene Images
22
The Eye Image Landmarks
The eye monitor will present images of the left eye of the subject when the eye camera
unit has been properly adjusted to obtain clear, in focus images of the subject's eye. The
images will be adjusted to look similar to those shown in Figure 4.3 above. Again, note
that both the pupil and corneal reflection threshold levels for Eye 1 are set to zero at this
time.
The high contrast eye image shown in Figure 4.3 is the result of the system operator
properly aligning the position of the head mounted eye camera and the infrared reflecting
hot mirror in front of the eye. Figure 4.4 has an expanded view of an eye image to clearly
show the eye landmarks. With the eye illuminated by the infrared (IR) light source
mounted on the headset, the pupil appears as a dark hole, or sink to the infrared light.
The IR illuminator also generates a bright spot off of the cornea, (the curved anterior
portion in front of the pupil). This bright spot is called the corneal reflection.
Figure 4.4: The Eye Imaging Camera Matrix and Eye Landmarks
Eye images similar to that shown above in Figure 4.4 are input to the RK-826PCI eye
tracker card that detects the dark pupil and bright corneal reflection data present in the
eye images. To track the eye in real time, the RK-826PCI eye tracking card processes the
video signal representing the eye images generated by the eye imaging camera. The
images of the eye contain dark video information corresponding to the pupil of the eye and
bright video information corresponding to the corneal reflection.
In the RK-826PCI eye tracker card, electronic circuitry generates voltage levels that are
continuously compared to the dark pupil and bright corneal reflection signals present in
the eye images. These voltage levels are called the PUPIL THRESHOLD and CORNEAL
REFLECTION THRESHOLD respectively. First, the operator manually adjusts the pupil
threshold level to discriminate the dark video information present in the image that
corresponds to the pupil signal. When the threshold display control button is enabled, the
dark pupil information that is discriminated by the pupil threshold level is displayed as a
bright overlay on the eye image. See Figure 4.5.
ISCAN ETL-600 Instructions
Section 4: Obtaining Eye & Scene Images
23
The operator then manually adjusts the CR threshold level to discriminate the bright
video information present in the image containing the corneal reflection. When the
threshold display control button is enabled, the bright CR information that is
discriminated by the CR threshold level is displayed as a black overlay on the eye image.
Figure 4.5 shows the eye landmarks being tracked as seen on the LSW eye monitor panel.
Figure 4.5: Eye Image With Matrix and Gate On
Once the operator has adjusted the pupil and corneal reflection thresholds to encompass
the pupil and corneal reflection targets, the operator enables a TRACK ACTIVE feature
that initiates automatic tracking of the pupil and corneal reflection over the eye image
area displayed on the monitor.
Another feature shown in Figure 4.5 above is the IMAGE GATE. This box is a two
dimensional window displayed on the eye image display monitor. The eye threshold and
eye tracking functions are only active inside the gated area. The size and position of the
image gate is adjustable by the system operator and can help to isolate the eye landmarks
for tracking in extremely cluttered eye images. The image gate can be turned on or off.
When the image gate is turned off, the eye tracker is active over the eye camera's full field
of view.
The video eye image display monitor over which each eye is tracked, is represented by a 0
- 511 pixel horizontal by 0 - 255 TV line vertical matrix. All pupil and CR position data
and image gate data is with respect to this grid. For example, if the pupil is in the center
of the eye image display monitor, the coordinates of the pupil position generated by the
RK-826PCI eye tracker would be 255 horizontal and 128 vertical. The coordinates for the
upper left corner of the eye image display monitor are 0H, 0V and the lower right corner of
the display is 511H, 255V.
The Scene Imaging Camera Matrix
The miniature color scene camera is mounted on the headset facing forward between the
eyes to capture a real time view of the world in front of the subject. The video from the
scene camera runs through the RK-630PCI Autocalibrator and is displayed on the scene
monitor in the LSW software window. The RK-630PCI Autocalibrator takes the eye
position data from the RK-826PCI Eye Tracker and transforms the raw eye position
signals into a point of regard indicator that is superimposed over the scene video.
ISCAN ETL-600 Instructions
Section 4: Obtaining Eye & Scene Images
24
The scene image display over which the subject's point of regard is presented is
represented by a 0 -511 pixel horizontal and 0 - 511 TV line vertical matrix. All point of
regard position data is with respect to this grid. Figure 4.6 shown below illustrates the
main landmarks present in the point of regard image shown on the scene monitor.
Figure 4.6: Scene Monitor Matrix and Point-of-Regard Indicator With Data Display
For example, if the subject was looking at a point directly in the centre of the scene image,
the coordinates of the point of regard would be 255H, 255V. The upper left corner of the
scene monitor display is 0H, 0V and the lower right is 511H, 511V.
Also shown in figure 4.6 above is the real time data display that shows the current
horizontal and vertical point of regard coordinates, the pupil diameter and a real time
elapsed time clock. The operator can turn off this display so as not to obscure any portion
of the scene image.
Obtaining Good Eye Images With the Headset
Have a cooperative human subject sitting relatively still, wearing the headset. At this
time, preferably select a subject that is not wearing eyeglasses. Adjustments of the
headset to compensate for subjects wearing glasses will be covered at the end of this
section.
The eye camera is a miniature television camera that is designed to capture clear, in focus
images of the eye. The eye is illuminated by a low level infrared light-emitting diode
(LED) that is positioned next to the eye camera, and the LEDs should be kept free from
dirt or mechanical obstructions.
ISCAN ETL-600 Instructions
Section 4: Obtaining Eye & Scene Images
25
Figure 4.7: Eye/Illuminator/Mirror Orientation
As shown in Figure 4.7, the plastic hot mirror is positioned in front of the subject's eye at a
roughly 45 degree angle, reflecting an infrared image of the eye into the eye camera. The
IR illuminator, mounted next to the eye camera, points downward to illuminate the eye
area, also reflecting off the hot mirror.
Figure 4.8 below shows typical eye images as seen by the head mounted camera, reflected
off of the hot mirror.
Figure 4.8: Image of the Eye, High-Contrast Pupil/CR
For optimal eye imaging the mirror should be free from dust, dirt or fingerprints. keep it
clean by blowing off dust with compressed air and cleaning it periodically with glass
cleaner and a soft cloth. The hot mirror is adjustable and can be tilted inwards and
outwards in order to center the eye image with respect to the eye camera.
ISCAN ETL-600 Instructions
Section 4: Obtaining Eye & Scene Images
26
There are two main ways to adjust the position of the eye image with respect to the
camera, and hence center the eye image on the eye monitor displayed in the LSW software
window.
First, tilt the hot mirror slightly up and down to see the eye image move up and down in
the eye monitor. Note that pushing the hot mirror in, towards the bottom of the eye will
push the eye image down on the eye monitor. Similarly, pushing the hot mirror up, away
from the bottom of the eye will push the eye image up on the eye monitor.
Figure 4.9 illustrates what happens when the hot mirror is tilted in this manner.
Figure 4.9: Tilting the Mirror In/Out
Adjust the position of the mirror to center the eye image in the field of view of the eye
camera.
Similarly, leaving the hot mirror in a fixed position and twisting the eye camera inwards
or outwards, will result in the same type of eye position adjustment. Figure 4.10
illustrates what happens when the camera is twisted in this fashion.
ISCAN ETL-600 Instructions
Section 4: Obtaining Eye & Scene Images
27
Figure 4.10: Tilting the Eye Camera In/Out
Note that when the eye camera is twisted inwards (towards the eye), the eye image moves
up on the eye monitor. Similarly, when the eye camera is twisted outwards (away from the
eye), the eye image moves down on the eye monitor.
Adjust the balance between the mirror position and the camera position so the eye is
centered in its eye monitor display.
SUBJECTS WITH EYE GLASSES
Subjects wearing eyeglasses may require particular adjustments due to the additional
bright reflections off of the front surface of the lenses from the IR light source illuminating
the eye. These bright reflections may obscure or interfere with the eye landmarks and
make the pupil or corneal reflection unable to be tracked by the RK-826PCI eye tracker.
Figure 4.11 shows the type of eye image that can result if the eye camera and mirror are
not properly aligned.
Figure 4.11: Eye Image With Glasses
ISCAN ETL-600 Instructions
Section 4: Obtaining Eye & Scene Images
28
With subjects wearing eyeglasses, generally tilt the eye camera inwards, towards the eye,
raising the position of the eye on the eye monitor. Then tilt the hot mirror outwards, until
the eye drops back down to the center of the monitor and the glare spots from the IR
illuminator move downwards, off the pupil area.
Figure 4.12 below demonstrates the adjustments required to obtain clear pupil and
corneal reflection images with subjects wearing eyeglasses.
Figure 4.12: Eyeglasses Adjustments
ISCAN ETL-600 Instructions
Section 5: Tracking the Eye
29
Section 5: Tracking the Eye
The eye tracker controls are located in the upper left hand side of the LSW main software
window. (See Figure 4.1) The control panel is configured for monocular eye tracking and
consists only of controls for Eye 1. The control panel contains all the functional
adjustments necessary to threshold and automatically track the pupil and corneal
reflection eye landmarks.
Figure 5.1 Eye Tracking Controls Panel
As shown in Figure 5.1 above, there are controls for the following functions:
A. Threshold: displays the threshold level of the detected pupil and corneal
reflection areas
B. Pupil Threshold Slider: Controls the threshold level for the pupil
C. CR Threshold Slider: Controls the threshold level for the corneal reflection
D. Pupil X-Hairs: Enables the pupil crosshair display on or off
E. CR X-Hairs: Enables the corneal reflection crosshair display on or off
F. CR Limit: Turns on and off a pre-set search limit for the corneal reflection
G. Image Gate: Turns on and off a two-dimensional image gate; eye tracking is
active only inside the gate boundaries
H. Auto: Enables automatic thresholding of pupil and corneal reflection
ISCAN ETL-600 Instructions
Section 5: Tracking the Eye
30
A. Threshold
The threshold function is enabled when the threshold box is checked. This function
displays on the eye monitor a bright overlay on the pupil, the level of which is controlled
by the pupil threshold slider (B) on the right side of the control panel. It also displays a
dark overlay on the bright corneal reflection; its level is controlled by the CR slider (C).
The eye tracker also has an automatic threshold mode (H), in which the eye images are
automatically processed by the eye tracker to select the optimal pupil and corneal
reflection threshold levels. The baseline settings for the automatic threshold controls for
the pupil and corneal reflection can still be adjusted via their respective slider controls,(B)
and (C).
Become familiar with the manual threshold adjustment procedure before using the auto
threshold mode. For optimal tracking of the eye, the pupil threshold level should first be
adjusted so the dark areas corresponding to the pupil are completely filled in with the
bright threshold overlay. Adjust the pupil threshold slider (B), up until the pupil is filled
in with the bright overlay. Watch the eye image carefully and adjust the pupil threshold
slider until the level looks like that in Figure 5.2 below
Figure 5.2: Pupil Threshold Adjustment
ISCAN ETL-600 Instructions
Section 5: Tracking the Eye
31
Next, the CR threshold control must be adjusted to detect and fill in the small bright
corneal reflection with the dark overlay. The images below in figure 5.3 show the proper
level of the CR threshold, adjusted using the CR threshold slider control (C). Note that
there is a dark threshold overlay covering the bright corneal reflection when the CR
threshold is properly adjusted. The following eye images also illustrate CR threshold
levels that are too high and too low.
Figure 5.3: Corneal Reflection Threshold Adjustment
When the pupil and corneal reflection threshold levels have been set in the proper range,
enable Track Active Figure 4.1 (4). If the Pupil X-Hairs and CR X-Hairs functions are
enabled, Figure 5.1 (D) and (E), turning on track active control enables eye tracking and
graph display functions. With both Track Active and the Pupil and CR X-Hairs on, you
should see a black cross hair centered on the pupil. The black pupil cross hair is displayed
on top of the bright threshold overlay.
ISCAN ETL-600 Instructions
Section 5: Tracking the Eye
32
The corneal reflection cross hair is also displayed, superimposed over the dark corneal
reflection threshold overlay. The eye image should look like the image shown in figure 5.4
below.
Figure 5.4: Corneal Reflection Crosshair with Threshold
The Pupil X-Hair function turns on and off the pupil cross hair. If the crosshair is present
and is solidly locked on the center of the pupil as the subject looks around, the pupil is
being properly tracked by the RK-826PCI eye tracker card. Note that the pupil cross hair
appears dark when the threshold function is enabled and turns bright when the threshold
function is turned off.
The CR X-Hair function turns on and off the corneal reflection crosshair. If the crosshair is
present over the center of the corneal reflection and is solidly locked onto the corneal
reflection as the subject looks around, the CR is being properly tracked by the eye tracker
circuit card. Note that the CR crosshair appears bright when the threshold function is
turned on and it changes to a dark crosshair when the threshold function is turned off.
Figure 5.5: Pupil & CR Crosshairs with Threshold Display Off
ISCAN ETL-600 Instructions
Section 5: Tracking the Eye
33
The image below in Figure 5.6 shows what a good eye image looks like with the threshold
and crosshair functions enabled. As the subject looks around the center +/-20 degrees of
visual angle the pupil and corneal reflection crosshairs should be solidly tracking their
respective targets.
Figure 5.6: Good Eye Tracking Image
The CR Limit function Figure 5.1 (F) enables a user programmable search area around
the pupil for detection of the corneal reflection. This function can be used if there are other
bright corneal reflection candidates in the eye image that might compete for detection as a
corneal reflection target. This function is normally disabled in system operation. The
system operator can define the search area for the corneal reflection based on a percentage
of distance form the pupil center. To adjust the CR limit, click on the AUX 1 or the AUX 2
tabs just to the right of the Eye 1 and Eye 2 control panels. The CR % numbers can be
adjusted to detect the corneal reflection within a plus/minus percentage of the pupil
horizontal and vertical size. The default detection area is 150% of the pupil horizontal size
and 150% of the pupil vertical size.
The Image gate function, see Figure5.1 (G), turns on or off a user adjustable two
dimensional window on the eye monitor display within which the pupil and corneal
reflection threshold and tracking functions are active.
The operator can adjust the top, bottom, left and right sides of this two-dimensional box or
gate over the full extent of the eye imaging area. Figure 5.7 shows the eye image with the
image gate feature turned both on and off.
IMPORTANT: getting a good trackable eye image is possible with
virtually every subject by using a combination of the camera and
mirror position adjustments and by adjusting the pupil and corneal
reflection threshold levels. In addition, adjustment of the span of the
image gate may help to eliminate some eye image artifacts.
ISCAN ETL-600 Instructions
Section 5: Tracking the Eye
34
Figure 5.7: Eye Image Gate
The video eye image area over which the eye is tracked is represented by a 0 - 511 pixel
horizontal by 0 - 255 TV line vertical matrix. All pupil and corneal reflection position data
and image gate position data is with respect to this grid. The horizontal edges of the image
gate can be adjusted between 0 - 511 pixels and the top and bottom edges between 0-255
TV lines.
To move the position of the image gate, click on the AUX 1 or AUX 2 panels just to the
right of the EYE 1 and EYE 2 control panels, in the Eye Tracking Controls area in the
DQW software window. Figure 5.8 shows the typical settings in the AUX panel.
Enter 3 digit numbers with the keyboard or use the mouse to scroll the numbers
associated with the left/right/top/bottom boundary settings, as shown in figure 5.8.
Figure 5.8: AUX Control Panel
ISCAN ETL-600 Instructions
Section 5: Tracking the Eye
35
In addition, in the eye tracking AUX control panels, there are settings for the maximum
and minimum pupil and corneal reflection area limits. These minimum and maximum
values enable the operator to spatially filter the eye images to detect the pupil and corneal
reflections that may be in the presence of dark shadows or bright reflections that might
compete with the desired targets for recognition by the eye tracker electronics. The
standard pupil and corneal reflection area limit settings are shown in figure 5.8 above.
At this point, if the pupil and corneal reflection are both robustly tracked by the eye
tracker, the next procedure is the alignment of the scene camera.
Adjustment of the Scene Camera
The scene camera is positioned between the eyes above the nose, on the headset, facing
outwards. The scene camera is mounted on a tilt mechanism that allows the operator to
move the scene camera up and down to align the scene image with the subject's central
field of view. The scene camera is press-fit into a ring holder that also allows rotation of
the camera to straighten out the scene image if necessary.
! Tilt the scene camera to line up the center of the scene image as displayed on the
scene monitor with the center of the subject's field of view.
! If required, rotate the scene camera to straighten the scene image displayed on the
scene monitor.
ISCAN ETL-600 Instructions
Section 5: Tracking the Eye
36
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ISCAN ETL-600 Instructions
Section 6: Eye/Scene Calibration
37
Section 6: Calibrating the Eye to the Scene
The ETL-600 system incorporates two distinct calibration procedures. The first calibration
procedure is called the point-of-regard calibration, which maps the eye position data to the
matrix of the head-mounted scene camera. The second calibration procedure is called the
eye angle calibration, which combines both the eye and head position data and maps them
to the global view camera’s image matrix.
Overview of Point-of-Regard Calibration Procedure
The point-of-regard calibration procedure can be performed either before or after the eye
angle calibration procedure. The point-of-regard calibration procedure maps the eye
position data calculated by the RK-826PCI eye tracker to the matrix of the head-mounted
scene camera.
The subject is instructed to view five calibration points within the field of view of the head-
mounted scene camera, resulting in a real-time indicator, superimposed over the video
display from the head-mounted scene camera, indicating precisely where in the image the
subject is looking. The point-of-regard calibration is covered in detail in this section.
Overview of Eye Angle Calibration Procedure
The eye angle calibration procedure combines both the eye and head position data and
maps them to the image matrix displayed by the global view camera. The global view
scene camera is fixed, generally to the side of the subject, and views a wide-angle image of
the subject’s visual field that includes the planar surfaces of interest to the experimenter.
The subject is instructed to look at five calibration points that are calculated by the
ISCAN software to be projected on a planar surface in front of the subject. The system
operator manually moves a laser pointer to superimpose the red laser spot precisely over
the position of each calibration point, as shown on the global view camera display. The
result of this calibration procedure is a real-time indicator superimposed over the global
view display showing precisely where the subject’s head and eye are pointing. This
calibration procedure precisely shows the subject’s combined head and eye position (also
called the line of sight or LOS) as it intersects with the planar surfaces surrounding the
subject.
Before the eye angle calibration can commence, the system operator must identify the
coordinates of the planar surfaces with respect to the 0X, 0Y, 0Z origin of the head tracker
source. These same planar surfaces also are to be defined with respect to the global view
camera matrix and this complete eye angle calibration procedure is described in detail in
Section 7.
Point of Regard Calibration
After the scene camera is properly aligned and the eye is tracked robustly while connected
to the eye tracking computer, a simple calibration procedure has been devised that first
instructs the subject to look at 5 points within the field of view, as seen by the operator on
the scene monitor display, to correlate the eye data to the scene image display. This
calibration procedure results in a point of regard output in which an indicator is
superimposed over the scene image showing precisely the subject's real-time point of gaze.
ISCAN ETL-600 Instructions
Section 6: Eye/Scene Calibration
38
Wearing the headset, the subject will be instructed to complete a calibration procedure
that involves looking at a series of 5 calibration targets mounted on a flat surface, such as
a wall or work area.
The five calibration targets should include a center calibration point and four outer points,
positioned at ±8 to ±10 degrees of visual angle with respect to the center.
The subject will then be verbally instructed by the operator to look at the 5-point
calibration target pattern mounted on the flat surface at a distance of about 3 to 5 feet
from the subject. The system operator must manually line up an indicator to be
superimposed over each of the 5 calibration points and enter the raw eye position data for
each point. After this calibration procedure, the subject is free to move about in their
environment, and the point of regard is represented as that same indicator moving about
over the scene monitor display.
Setting Up the Calibration Targets
The calibration points are 5 high contrast stick-on targets that can be affixed to a wall,
computer screen or other flat surface. The typical eye to calibration point distance should
be set for the approximate range of the eye to stimulus distance expected in the
experimental set up. Set up the targets as shown in Figure 6.1 below, attaching the
stickers (supplied) to the front of the monitor.
Figure 6.1: Calibration Procedure
After the calibration points have been set up as described above, the subject should put on
the headset, and clip the cable to an article of clothing for stability.
Have the subject sit in the chair positioned approximately 2 to 5 feet from the calibration
targets. Ask the subject to look in the general area of the calibration targets on the surface
facing the subject.
ISCAN ETL-600 Instructions
Section 6: Eye/Scene Calibration
39
Checking the Eye and Scene Images
Verbally instruct the subject to keep their head relatively still and look at the center
calibration target. Make sure that all 5 of the calibration targets are clearly visible in the
scene image and that the pupil and corneal reflection eye landmarks are robustly tracked
as the subjects looks at each calibration point in turn. Only after this quick check of the
eye and scene data, can the calibration procedure begin.
The Point of Regard Calibration Procedure
The ETL-600 is now set up to allow the operator to perform a calibration of the eye data.
The monocular eye tracker position data (represented by the positions of the pupil and
corneal reflection cross hairs on the eye monitor display) will be transformed into point of
regard coordinates by the calibration procedure.
In the calibration procedure, the eye position data will be related mathematically to the
known calibration points visible in the scene monitor display.
A calibration model will be constructed by the RK-630PCI Autocalibrator processor that
relates the subject's eye position data to coordinates in a matrix superimposed over the
scene video display, yielding real time point of regard position. The point of regard is
represented as an indicator that moves over the images of the scene.
Figure 6.2: RK-630 POR Scene Image
The scene image is represented by a 0 -511 pixel horizontal by 0 - 511 TV line vertical
matrix. The point of regard indicator is comprised of a cross symbol that represents the
position of the subject’s left eye, as shown in Figure 6.3 below.
Figure 6.3: Symbol of Point of Regard
The point of regard indicator is drawn by the RK-630PCI as a combination of
black and white symbology so it can be visible to the system operator when
superimposed over scene images that contain both bright and dark scene content.
ISCAN ETL-600 Instructions
Section 6: Eye/Scene Calibration
40
The data display feature overlaid on the operator monitor output of the RK-630PCI
indicates pupil diameter in pixels, horizontal and vertical point of regard within the 0 -511
matrices and a real time 60Hz elapsed time clock that may be used to time events or to
synchronize the recorded video output with stored point of regard data in the eye tracker
computer.
Figure 6.4: POR Data Display
Performing the Point of Regard Calibration
Click on Track Active and then click on the Scene Monitor expansion box to the upper
right of the Scene Monitor display. This enlarges the scene image so it can be clearly
viewed by the operator. In addition, clicking on the expansion box calls up the P.O.R.
Calibration Controls, directly below the Eye Tracking Controls panel. (In some older
software versions it may be necessary to manually click on the Options button to cycle
through the panel selections until the P.O.R Calibration Controls appear).
Figure 6.5: POR Calibration Control Panel with Large Scene Image
The POR Calibrator starts up in the RESET mode. In the RESET mode, the operator can
move the point-of-regard indicator over the area of the scene monitor display by using the
mouse to place the cursor inside the gray pseudo-screen area, clicking and dragging the
operator’s active calibration point, thereby moving the POR indicator in the scene monitor.
Make sure that the subject's eye is open and that the center calibration point is clearly
visible in the scene image.
Click the POR Calib button in the POR Calibration Control panel, and the status box
below POR Calib will read CENTER.
Verbally instruct the subject to keep the head relatively still and to look at the center
calibration target.
Position the cursor in the gray calibration pseudo-screen and click and drag to line up the
POR indicator, as viewed on the expanded scene monitor display, directly over the center
calibration target. Precise positioning of the indicator is achievable using the rollers on the
numeric display directly below the pseudo-screen.
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Section 6: Eye/Scene Calibration
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Confirm that the subject's eye images are similar to those shown in Figure 6.6 below,
appearing to look straight ahead at the center point of the calibration targets. Make sure
as well that the pupil and corneal reflections are properly tracked as indicated by the
position of the related cross hairs. If necessary adjust the pupil and corneal reflection
threshold levels for proper tracking and position the image gate to more tightly encompass
the eye landmarks, as described in section 5 above.
Once the eye is properly tracked and the POR indicator is lined up over the center
calibration target, enter the center calibration point by right clicking on the mouse while
the cursor is in the gray pseudo-screen box. If the subject inadvertently blinks or closes
their eye as the data is entered, this may result in the input of bad data to the calibration
model. If this happens, click on RESET and start the calibration procedure over or use the
SELECT control to go to the CENTER point again.
Figure 6.6: Center Calibration Point
As soon as the calibration point has been entered, the status box will indicate UPPER
LEFT and the upper left calibration indicator will be circled in the pseudo-screen.
Now, while keeping their head still, instruct the subject to shift their fixation and stare at
the upper left calibration target.
Watch the eye images carefully to see the subject shift their fixation to the upper left
calibration target and then, with the operator’s cursor positioned in the gray pseudo-
screen, click and drag the POR indicator exactly over the upper left calibration target as
shown in Figure 6.7. If necessary, use the roller controls below the pseudo-screen to
precisely position the indicator over the upper left calibration target.
Again, make sure that the eye is clearly visible and is properly tracked.
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Enter the upper left calibration point by right clicking in the gray pseudo-screen.
Figure 6.7: Upper Left Calibration Point
After entering the upper left point, the calibrator will automatically indicate the UPPER
RIGHT in the status box and the circle in the pseudo-screen will move to encircle the
upper right calibration point.
Instruct the subject to fixate the upper right target and carefully watch the eye image
until you see the subject's fixation shift to the upper right calibration target. Move the
calibration indicator so it is exactly overlaid on the upper right calibration target, again
making sure that the eye landmarks are being properly tracked. With the operator’s
cursor in the pseudo-screen, right click the mouse to enter the upper right calibration
point.
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Figure 6.8: Upper Right Calibration Point
Repeat the above steps for the LOWER LEFT and LOWER RIGHT calibration points.
Refer to Figures 6.9 and 6.10 for representations of the LSW screens at these points.
Figure 6.9: Lower Left Calibration
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Figure 6.10: Lower Right Calibration
After successful entry of all 5 calibration points, click on RESET in the POR Calibration
Controls panel. At this juncture, the 5 point calibration model is calculated by the RK-630
Autocalibration system and the POR OUT button should become active, and ready to be
enabled.
Click on the POR OUT button. If the 5 point calibration was successful, and the subject is
still at the 3 to 5 foot distance from the calibration targets, the point of regard indicator
generated by the calibration model should be overlaid onto each of the calibration targets
when the subject is instructed to look at them in turn. When satisfied with the results of
the calibration, the operator should now peel off the calibration stickers.
Figure 6.11a: POR Output Active After Calibration
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Figure 6.11b: POR Tracking Enabled After Calibration
A BNC "T" is provided with the system to tee off the RK-630PCI Operator Video Output
for recording purposes.
Note that after the calibration has been completed and POR OUT enabled, the POR
calibration indicator can also be manually offset by the operator using the horizontal and
vertical roller controls below the gray calibration pseudo-screen. This function can be used
to fine tune the output as necessary without re-calibrating the subject.
This completes the standard point of regard calibration procedure for the ETL-600.
Calibration Auxiliary Controls
The tab labeled "AUX 1" to the right of the main POR Calibration Controls panel allows
the operator to adjust various parameters relating to the POR calibration system. Figure
6.12 describes the various parameters that can be adjusted below.
Figure 6.12: POR AUX Panel Settings for Monocular Operation
SOURCE refers to how the data from the eye is gathered and displayed as a point of
regard indicator, “A” mode meaning the signal from the left eye.
The ICON setting controls the representation of the point of regard indicator. The default
mode is SYMBOL, a stylized plus shown in Figure 6.3. XHAIR is a full screen cross hair.
EDGE HAIR is a bright pip within dark borders displayed at the right and bottom edges of
the scene monitor display.
POR Avg denotes the number of video field averaging of the point of regard indicator. The
POR Avg is selectable from 1 to 24 video fields.
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Storing a Calibration Model
Once a successful calibration model for a subject has been calculated by the calibration
and offset procedure, the operator can save this model to be run again with the same
subject.
After a successful calibration of the recorder output, to save a calibration model, disable
Track Active and click on the file menu in the upper left hand side of the LSW software
window.
From the file menu, select "SAVE ISCAN POR CALIB FILE AS..."
Figure 6.13: LSW Window With the Save Selection
The SAVE POR CALIBRATION FILE window will open and the operator should direct
the SAVE IN location to be the ISCAN LSW folder.
Type an identifying file name, making sure to have a .pcl file-type suffix, and click on the
SAVE button.
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Figure 6.14: Save Calibration File Name
Recalling a Calibration Model
To open a previously saved calibration file, disable Track Active and click on the file menu
in the upper left of the LSW software window.
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Figure 6.15: Open Calibration File
Select "OPEN ISCAN POR CALIB FILE..." from the drop down file menu.
The OPEN ISCAN POR CALIB FILE window will open and select the appropriate .pcl file
by double clicking on it.
The calibration file will be automatically loaded into the calibrator.
Now, when the POR Calibration Control panel is brought up, either by clicking through
the OPTIONS button or expanding the scene image display, the POR OUT control will be
active as shown in Figure 6.16 below, and able to be turned on by the operator.
Figure 6.16: POR Out Active
Enable Track Active and then click on the POR OUT control button to run the recalled
calibration model.
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Section 7: Eye Angle Calibration
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Section 7: Eye Angle Calibration
This procedure is the most complicated part of the ETL-600, as it involves measuring and
entering data to correspond to the position of the planar surfaces surrounding the subject.
The ETL-600 is normally used to automatically calculate where the combined eye and
head vector (the LOS) of the subject intersects various planar surfaces that surround the
subject in a real-world environment. The subject might be seated in a car or aircraft
cockpit, in a power plant simulator, or surrounded by a grouping of computer monitors.
The ETL-600 is used to display exactly where, at what time, and for how long the subject
looks at objects of interest to the experimenter in the surrounding work area. The planar
surfaces can include instrument clusters, radar screens, consoles, windows, or any group
of objects that can be reduced to planar surfaces.
Part A: Mapping of the Planar Surfaces
The planar surfaces must be mapped with respect to an origin point, at location 0X, 0Y,
0Z. This origin point is the center of the magnetic source cube, and the X, Y, and Z axes
are shown in Figure 7.1.
Figure 7.1: 3D Mapping of Multiple Planar Surfaces
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The directions of the X, Y, and Z axes follow the right-hand rule:
" The X-axis is positive in front of the magnetic source pointing towards the first planar
surface and negative out the back of the source.
" The Y-axis is positive pointing out of the left side of the source and negative going out
of the right side of the source.
" The Z-axis is positive exiting the top of the source, and negative pointing towards the
bottom, of floor of the room.
The first planar surface is called Plane 1, and should be specified as the planar surface
most central and normal in the subject’s field of view.
An example using three planes is shown in Figures 7.2a and 7.2b. A 26” diagonal
computer monitor is positioned in front of the subject and is defined as Plane 1. Plane 2 is
a 17” diagonal computer monitor positioned to the right-hand side of the 26” monitor and
tilted inwards at a 45° angle. Plane 3 is a 17” diagonal computer monitor positioned to the
left-hand side of the 26” monitor and tilted inwards at a 45° angle. (The diagram in Figure
7.2b shows only Planes 1 and 2.) The center of magnetic source cube is positioned 41” in
front of the right edge of the monitor. The height of the magnetic source is adjusted so the
center of the source is 44” from the floor.
Figure 7.2a: Multiple Planar Surfaces (Viewed from Above)
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Figure 7.2b: Multiple Planar Surfaces (Partial View)
Note that the X, &Y, and Z coordinates of the planar surface, in this case a computer
monitor, are measured at the edges of the active LCD monitor area. Once the X, &Y, and Z
coordinates have been measured, using the supplied tape measure, they must be entered
into the ISCAN Environment Planes Layout Editor.
To enter the coordinates of the planar surfaces into the ISCAN Environment Planes
Layout Editor , follow the steps below:
Disable Track Active, and click on the multi-color planar surface icon on the top icon row
at the top of the LSW software as shown in Figure 7.3.
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Figure 7.3: Environment Planes Layout Icon
The ISCAN Environment Planes Layout Editor panel will come up, shown in Figure 7.4a.
Figure 7.4a: Environment Planes Layout Editor for Plane 1
Using the rollers to the right of the Total Planes box, enter the number of planar surfaces
to be designated. (In this example we are using 3.) Select the first plane to edit as 1. Select
Calib Plane as 1.
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Plane 1 should be designated as the planar surface in front of and normal to the subject.
Plane 1 is always used as the calibration plane for the eye angle calibration.
Figure 7.4b: Measurements to Establish the Relationship of Magnetic Source to Plane 1
Using the tape measure provided, measure the distance of the center of the magnetic
source cube to the front surface of plane 1. (Note: all measurements must be in inches.) If
plane 1 is perpendicular to the table it is sitting on, this distance can be entered into all of
the four X coordinates. In the example shown in Figure 7.5a, the X distance for the upper
left, upper right, lower left and lower right coordinates is 41.00”.
Since the center of the source cube is positioned on a line with the right edge of the
monitor designated as Plane 1, the Y coordinates of the upper right and lower right points
will be 0.00, and should be so entered.
The distance of the upper left and lower left points on the Plane 1 monitor from the center
of the source is 23.00” in the positive Y direction and can be entered as 23.00 for the upper
left and lower left Y coordinates.
The center of the source is measured as 44” from the floor. The upper left and upper right
coordinates of the monitor are measured to be 48” from the floor. To get this number we
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first measured the distance to the tabletop from the floor as 31”. The top edge of the
monitor is an additional 17” from the surface of the table. Therefore, the Z coordinates for
the upper left and upper right coordinates is 4.00”.
The lower left and lower right coordinates of the monitor are measured as 4” up from the
surface of the table, 35” from the floor, a difference of -9.00” from the center of the source.
Therefore the lower left and lower right Z coordinates are both -9.00”.
Refer back to Figure 7.4a to see the ISCAN Environment Planes Layout Editor with these
coordinates entered.
Using the mouse and computer keyboard, now manually enter the X, Y, and Z locations for
the edges of the upper left, upper right, lower left and lower right coordinates for the first
planar surface into the manual plane coordinate entry boxes. Again, make sure all
measurements are entered as inches.
The Edit Plane Info controls at the left hand side of the Manual Plane Coordinate Entry
panel can be used to fine-tune the X, Y, and Z position of the planar surface, once the
coordinates have been manually entered. For example, once the properly measured
coordinates of a planar surface have been manually entered, and it becomes necessary to
move the position of the magnetic source slightly closer or farther away from the plane in
the X direction, you can set the Increment in inches to values of 0.25” and click on the Left
X Pos arrow to move the plane farther away from the 0,0,0 origin of the magnetic source.
Enter the coordinates for Planes 2 and 3 as shown in Figure 7.5b below.
Figure 7.5: Environment Planes Layout Editor for Planes 2 & 3
After all of the plane coordinates have been entered, click OK to get back to the ISCAN
LSW Main Screen.
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Part B: Registration of Planar Surfaces with the Global View Scene Monitor
The next required mapping procedure is to register the positions of the mapped planar
surfaces with the global view scene camera.
The global view scene camera should be positioned to the side of the subject’s work area to
view all the planar surfaces. In this example, we have a 3-monitor display. The center
monitor is a 26” diagonal, and both of the side monitors are 17” diagonal LCD monitors.
Adjust the position of the global view camera to encompass all the planar surfaces. Adjust
the focus and iris settings of the lens to present a clear, in-focus image of the environment
a shown in Figure 7.6.
Figure 7.6: Monitor Schematic
To register the positions of the planar surfaces to the global view scene image, first click
on the box to expand the global view monitor so it can be seen clearly by the system
operator. Figure 7.7 shows the global view scene camera output displayed on the global
view monitor.
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Figure 7.7: Global View Monitor
Note that when the global view monitor is expanded to fill the graph areas, the video
display unit controls appear in the Auxiliary Control panel. In older versions of the LSW
software, it may be necessary to click on the Options button until the VDU controls
appear. The VDU Control panel is shown in detail in Figure 7.8.
Figure 7.8: Video Display Unit Control Panel
To begin the registration procedure, select the VDU2 panel for Global View, and select
Plane 1 in the Plane # box by clicking on the roller arrows. With Plane 1 selected, click on
the top roller arrow of the Active Item box to select the center plane registration point.
Center will appear in the Active Item box, and 5 small registration squares will appear in
the gray pseudo-screen area. The center registration square is circled, indicating that the
registration point indicator must be positioned by the operator over the geometric center of
the first planar surface, as seen in the global view monitor display.
Use the mouse to click on and drag the circled registration square, and move it around in
the gray pseudo-screen area until the registration point indicator is positioned over the
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geometric center of Plane 1 in the Global View Monitor. After the indicator is positioned as
shown in Figure 7.9, releasing the mouse button registers the center point. Now left-click
on the Active Item up arrow to select the upper right registration point.
Figure 7.9: Center Point Registration
Again position the cursor in the gray pseudo-screen. Click and drag until the upper left
registration point indicator is precisely over the upper left corner of the active area of the
planar surface. See Figure 7.10.
Figure 7.10: Upper Left Point Registration
Repeat this procedure for the upper right, lower left, and lower right points, as shown in
Figure 7.11.
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Figure 7.11a: Upper Right, Lower Left, Lower Right Points Registration
Once the first plane has been registered, so that all four corner points and the center point
have been ascertained, click on the Active Item box so that it is cleared, as shown in
Figure 7.11b. This allows registration to move to the next plane.
Figure 7.11b: Clearing the Active Item Box
The entire procedure must be repeated for all subsequent planar surfaces.
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In the Global View Image display, as seen in Figure 7.12a, there are three planar surfaces,
Plane 1, Plane 2, and Plane 3. For this example, Plane 2 is the right-most 17” computer
monitor, and Plane 3 is the left most.
Figure 7.12a: Global View Image Display of Multi-Plane Area
Click on the Up roller next to the Plane # box to increment the Plane number. Figure
7.12b shows each of the video display unit controls with Plane 1, Plane 2, or Plane 3
selected. As described above for Plane 1, align the center, upper left, upper right, lower left
and lower right registration points in the corresponding corners of the planar surfaces.
Figure 7.12b: VDU Control Panels for Multiple Planes Registration
When each of the planes has been registered with respect to the global view monitor
image, the LSW software can then mathematically calculate the intersection of the 6-
degree-of-freedom head position data coming from the Polhemus head tracker, and display
the intersection of the head vector with the planar surfaces on the global view image.
Once the planar coordinates for the surfaces of interest have been entered, it is a good idea
to check the measurements a second time for accuracy and uniformity. For example, in
reviewing the data for the three planar surfaces entered in this instructional
configuration, the Z coordinate for the lower left and lower right points for all three planes
must be -9”, the same for all the monitors since the bottoms of all the monitors are aligned
as shown in Figure 7.13.
They are all the same height with respect to the center of the magnetic source, the origin.
A quick check of the coordinate data should show up any inconsistencies in data entry or
measurement.
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Section 7: Eye Angle Calibration
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Figure 7.13: Matching Z Coordinates
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When the system operator is confident that the data is properly entered in the ISCAN
Environment Planes Layout Editor, and each of the planes has been registered in the
global view video display unit controls panel, it is time to actually run the head tracker
with the LSW software and verify that the head data is properly interfaced to the LSW
program, and that it is properly intersecting the planar surfaces as measured and input to
the LSW program. After the head position data is verified, the system operator can
commence with the eye angle calibration.
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Part C: Verification of Head Vector Intersection with Planar Surfaces
At this point, exit from the LSW program. To exit from the program, disable Track Active,
click on the file menu in the upper left hand side of the LSW screen, and select the exit
command. Click the OK button to confirm program exit. The Windows 7 start-up screen
with the ISCAN ETL-600 icon is now visible.
Have a test subject put on the headgear, adjust the rear lanyard strap for a comfortable
tight fit, and clip the cable clips to the subject’s clothing to stabilize the headgear and
cables.
Have the subject sit in front of the magnetic source, keeping the head tracker sensor on
the right-hand side of the head within about a foot or so of the source. While looking at the
scene monitor in the LSW control window, adjust the tilt and/or rotation of the scene
camera as necessary to encompass the center monitor (Plane 1). Review Section 6 if
necessary. (If no subject is available, put the headgear on the mannequin head and
position it on a box or some books to put it in the same physical space as a human subject
would be positioned in front of Plane 1.)
The global view monitor display should show the subject seated in front of the center
monitor, and the other two planar surfaces should also be visible to the greatest extent
possible. (The subject will inevitably block a portion of the view.) See Figure 7.14.
Figure 7.14: Global View Scene Image Display
Turn on the Polhemus head tracker. (If it is already on, turn it off and then on.) Observe
the Sys Status LED on the front right of the head tracker panel. It should flash a few
times red, and then turn green, indicating successful power-up.
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Only after the head tracker green status LED is on, double-click on the ISCAN LSW icon.
After the LSW program opens, click on Track Active. Immediately, graphical data should
appear in Graph B, showing the real-time measured positions of the head X, Y, Z and
Azimuth, Elevation, and Roll data. The LSW window will appear as in Figure 7.15 below.
Figure 7.15: LSW Window with Mannequin Head Data.
Note that the head position numbers are appearing as stable values, indicating there is
minimal movement between the head sensor and the source.
Click the Options button until the Eye Angle Calibration controls panel is visible in the
Auxiliary Controls panel.
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Figure 7.16: Eye Angle Calibration Controls Panel
The eye angle calibration panel should open in the Reset mode. Below the Calibrate
button is an operator-selectable angle in degrees. This is normally set in the five to eight
degree range and represents the plus/minus eye angle in degrees that the subject will be
instructed to look at for the eye angle calibration
The Angle Out control button is disabled (grayed-out), but will become enabled after the
calibration procedure has been completed.
The Boresight Head button establishes a center location on the first planar surface that
corresponds to where the subject should be instructed to begin the eye angle calibration
procedure. The Boresight command basically “zeroes out” the position of the head sensor
with respect to its position to the source origin and positions. The intersection of the head
vector at the center of Plane 1 is, in most cases, the center of the screen directly in front of
the subject.
Click the Boresight Head button once and watch to see whether the head position
indicator appears on the global view monitor as shown in Figure 7.17.
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Figure 7.17: ETL-600 Boresight in Center Plane 1
If the head position intersection indicator is not exactly in the center of Plane 1, click the
Boresight Head button one or two more times to adjust it closer to the center position.
Once the head position intersection indicator has appeared at the center of Plane 1 in
response to the Boresight Head command, instruct the subject to move his or her head
linearly pointing towards the multiple planar surfaces, or just rotate the mannequin head
to point at the surfaces. As the head is rotated, the head position intersection indicator
should move linearly over the mapped planar surfaces, as shown in Figure 7.18 below.
NOTE: If there is no indicator appearing anywhere within Plane 1,
even though everything is set up as described above, check first that
all the head tracker output is visible in Graph B, and verify that
they respond to real head movements. If the head position graphs
are not moving, exit the LSW program and re-start the Polhemus
head tracker before opening the LSW program again. Otherwise,
check that the planar coordinates have been measured correctly and
have been properly entered into the plane editor panel.
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Figure 7.18: Movement of the Head Vector Intersection Indicator
Tilting the head up will also move the target head intersection indicator up in the global
view display, while tilting the head down will have the opposite effect.
As the head moves between the planar surfaces, the head vector indicator should
disappear at the edge of one monitor, and re-appear at the active area of the adjacent
monitor. This test of the head intersection with the planar surfaces confirms that the
planar coordinates have been properly entered, and that the registration points of the
planar surfaces to the global view monitor have been properly aligned over each plane.
Upon successful completion of this step, the operator can proceed to the eye angle
calibration.
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Part D: Eye Angle Calibration
The eye angle calibration procedure involves prompting the subject to look at five points of
known degree of visual angle with respect to the head position vector. Upon completion of
the eye angle calibration, the combined eye and head vector intersection with the planar
surfaces will be superimposed over the global view monitor as a real-time indicator, in
place of the head-only vector seen by the operator and described in the previous section.
The angular magnitude of each of the five calibration points will be summed with the head
vector, and the operator will be shown the precise point that the subject should look at,
superimposed over the global view monitor. The five calibration points are arranged in a
cross pattern: Center, Left, Right, Top, and Bottom.
With the human subject seated in front of plane 1 and facing normal to the plane, enable
Track Active. Enlarge the global view monitor, then click the Options button until the eye
angle calibration controls panel is visible. With the subject’s head and eyes pointing
straight at the center of Plane 1, click the Boresight Head button several times in
succession until the head intersection indicator is in the center of Plane 1 as shown in
Figure 7.19.
Figure 7.19: Boresight in Center Plane 1
Click on the Calibrate button in the eye angle calibration controls, and five calibration
points will show up in the gray pseudo-screen, as shown in Figure 7.20.
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Figure 7.20: Eye Angle Calibration Center
The first calibration point is the center, as indicated in the dialog box directly below the
gray pseudo-screen, next to the Enter Cal button. The center calibration point is also
circled in the gray pseudo-screen.
The position of the center calibration point that the subject should look at is projected onto
the operator’s global view monitor (ISCAN’s point-of-regard symbol discussed in Section 6,
and used here as the subject’s eye and head vector intersection indicator), and the system
operator must instruct the subject to look at that precise point on the screen of the Plane 1
surface. Note that the indicator moves as the subject moves his head, so the subject should
be instructed to make every effort to remain relatively still during the calibration process.
There are two methods for directing the subject where to fixate. If the Plane 1 computer
has its own mouse, the operator can use that mouse to line up the indicator for the Plane 1
monitor precisely at the indicated point on the screen as shown on the global view
monitor. Alternatively, the operator can position the laser pointer precisely so that its red
dot is superimposed over the open control area in the indicator that is seen on the global
view monitor image.
Figure 7.21: Laser Pointer Inside Center of Indicator
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The operator must carefully position the laser spot or indicator so it is within the open
center area of the indicator (see Figure 6.3), to correlate the eye position data with the
center calibration point.
Make sure that the eye parameters are properly tracked (Section 5, Tracking the Eye)
when instructing the subject to fixate the indicator or red dot. Click the Enter Cal button
or right-click the mouse positioned in the gray pseudo-screen area to enter the center
calibration point eye position data.
As soon as the center point is entered, the circle will jump to the left calibration point, and
the dialog box will read Left. The indicator’s position on the global view monitor will move
to the left by the increment in degrees selected by the operator. (In this example, the
calibration increment is 5 degrees.) The operator must again line up either the mouse or
the laser spot to be visible to the subject at exactly the point on the Plane 1 surface
covered by the center of the left calibration indicator on the global view monitor.
As soon as the operator has lined up the laser dot or indicator with the left calibration
point on the global view monitor, instruct the subject to look at it, check that the eye
parameters are being tracked, and right-click the mouse in the gray pseudo-screen to
enter the left calibration point.
Figure 7.22a: Left Calibration Point
The circle in the pseudo-screen will then surround the right calibration point, and the
dialog box will increment to Right. Follow the same steps as above for the Right, Top, and
Bottom calibration points.
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Figure 7.22b: Right, Top, and Bottom Calibration Points
Click on the Reset button. This will cause the eye angle model to be calculated by the LSW
software, making the Angle Out control available for selection.
Click on the Angle Out control button, and the combined eye and head vector intersection
point with the planar surfaces will be displayed on the global view monitor as a real-time
indicator. Instruct the subject to fixate some easily defined points within the planar
surfaces to ensure that the calibration is good. One quick test is to move the laser spot
over the planar surfaces, ask the subject to look at it, and verify that the eye and head
vector intersection indicator is properly indicating the subject’s eye and head position.
At this juncture, the ETL-600 should be successfully calculating the eye and head position
of the subject’s viewing the planar surfaces in the surrounding environment.
Graph A, shown in Figure 7.23 below, displays the real-time plane number (PlnIntNum1),
in this example either 1, 2, or 3, and the X and Y locations over each of the planes. For
example, PlaneInt H1 is the X location of the planar surface in units between 0 and 511,
and PlaneInt V1 is the Y location of the planar surface in units between 0 and 511.
These three data packets identifying the plane number and X,Y location on the plane at
which the subject is looking can be output via the serial port to a host computer for real-
time operations or stored in the ISCAN eye tracking computer for off-line analysis.
ISCAN ETL-600 Instructions
Section 7: Eye Angle Calibration
71
Figure 7.23: Graph A in the LSW Window
Eye-Sensor Measurements
The eye angle calibration controls also contain an AUX1 tab. Clicking on the AUX1 tab
opens a panel that allows the operator to enter the precise X, Y, and Z offset (in inches) of
the subject’s left eye with respect to the position of the head position sensor, as shown in
the diagram in the AUX1 tab.
Figure 7.24: AUX1 Tab and Panel
Using the roller controls at the right-hand side of the X, Y, and Z data boxes, the operator
can dial in the appropriate values for the X, Y, and Z location of the subject’s left eye with
respect to the center of the head position sensor, along with the distance of the center of
the nose to the sensor. The nose-sensor distance becomes an important parameter when
the system is optionally configured for binocular eye tracking.
The X dimension in inches represents the distance the eye is from the center of the sensor,
in side view. The positive axis of the X direction is how forward the eye is to the sensor in
a side view.
The Y dimension, in inches, represents how far to the left or right the left eye is positioned
with respect to the sensor, looking straight on at the subject. The positive axis of the X
direction is to the right side of the sensor, viewed straight on, facing the subject.
ISCAN ETL-600 Instructions
Section 7: Eye Angle Calibration
72
The Z direction, in inches, represents the height of the left eye, with respect to the head
position sensor, looking at the subject straight on. The positive axis of the Z direction is to
the top of the sensor, as viewed straight on, facing the subject.
The negative value for the Z direction in Figure 7.24 indicates that the eye is 1.5” below
the level of the sensor, in the safety glasses headset.
Figure 7.25: Safety Glasses Headset, Two Views
ISCAN ETL-600 Instructions
Section 8: Graph Display Controls
73
Section 8: Graph Display Controls
The graph displays are located in the center of the LSW software window. The graphs
allow the operator to display and view any of the parameters associated with eye tracking,
input/output operations, or other auxiliary functions.
Any of the signals displayed in the graphs can be manipulated by the controls on the right
hand side of the graph displays to adjust their scale and position.
The main features of the graph display and control panel can be seen in Figure 8.1 below.
Please note that Track Active must be enabled for display of graph data.
Figure 8.1: Graph Control & Display Area
The parameter list box shows the parameter selected by the operator for display. Clicking
the green box to the left of the parameter display brings up a list of all parameters that
can be shown in the graphs. The list of allowable graph parameters depends on what
auxiliary functions might have already been selected by the operator running in the LSW
software.
For example, if the LSW software has been configured to monitor blinks [Section 9(A)],
then parameters relating to blink count and blink state will be available for graph display.
ISCAN ETL-600 Instructions
Section 8: Graph Display Controls
74
If the blink monitoring subsystem has not been enabled, these parameters will not be included in
the graph parameter selection list.
Double-click on the desired parameter to load it into the parameter display box.
To the right of the graph parameter display box is a numerical representation of the parameter
value. Further to the right is the graph color selection control panel. Clicking on the colored box
brings up a color panel display. Clicking on any of the color boxes will change the color of the
graph to the selected color.
Clicking on the Activation button enables all graph scaling control functions for this selected
graph parameter.
The scaling controls include a default button that automatically scales the graph to a default
value. For example, if the pupil horizontal position (PupilH1) is activated and the default button
is clicked, the scale of the graph defaults to the full screen range of the horizontal pupil position
matrix, 0 – 511.
- Gain Controls: The in and out buttons amplify or reduce the gain of the signal as shown on
the graph, with a corresponding increase or decrease of graph resolution as shown on the
scale on the left hand side of the graph display.
- Offset Controls: The up and down buttons shift the position of the signal up or down with
a corresponding shift in the position numbers (scale) on the left hand side of the graph
display.
- Invert Control: Clicking on the INV button inverts the polarity of the signal on the graph.
- Center Control: Clicking the CTR button automatically centers the signal on the graph
display.
- Center Control for Two Signals simultaneously: Clicking the Center A/B button,
positioned between the two graphs, centers two signals, each one that is activated in each
graph.
After the scaling of the graphs has been completed, the scaling controls for the graph parameter
can be de-activated by clicking the No Active Param Scale button. The analog output signals
remain scaled with the values loaded into the scaling controls.
Note that the range of an analog output signal is represented full-scale over the entire height of
the graph. For example, the +/- 5-volt range of the analog output signal will encompass the full
scale from top to bottom of the graph.
Please note in Figure 8.1 that the Activation
button for the graph scaling functions to the
left of the green parameter selection button.
ISCAN ETL-600 Instructions
Section 8: Graph Display Controls
75
A large number of parameters are available within the LSW software for recording or viewing
depending upon the particular hardware and software configuration.
Following is a table defining the representations of the most often encountered possible
parameters. Note that many of the listed parameters will NOT be available in your setup, but
might become active if other hardware or system configurations become operational.
In both the binary (.dqw) and ASCII (.tda) file versions, parameters appear as strings. Each file
type has a different set of string listings as shown in the appropriate columns below.
Parameter Label Parameter (.dqw) Param (.tda) Description
....................... PRM_NULL N/A No Selected Parameter
Eye Tracker #1
.Pupil.H1........ PRM_PUPILH1 Pupil H1 Eye Pupil Horizontal Center Position
.Pupil.V1........ PRM_PUPILV1 Pupil V1 Eye Pupil Vertical Center Position
.Pupil.D1........ PRM_PUPILD1 Pupil D1 Eye Pupil Horizontal Diameter
.Pupil.VD1....... PRM_PUPILVD1 Pupil VD1 Eye Pupil Vertical Diameter
.Pupil.A1........ PRM_PUPILA1 Pupil A1 Eye Pupil Area
.C.R..H1......... PRM_CRH1 C.R. H1 Eye Corneal Reflection Horiz. Position
.C.R..V1......... PRM_CRV1 C.R. V1 Eye Corneal Reflection Vertical Position
.P-CR.H1......... PRM_PCRH1 P-C.R. H1 Eye Pupil to Corneal Refl. Horiz. Difference
.P-CR.V1......... PRM_PCRV1 P-C.R. V1 Eye Pupil to Corneal Refl. Vertical Difference
.Blink.St1....... PRM_BLNKST1 Blnk St1 Eye Blink Status
.Blink.Cnt1...... PRM_BLNKCT1 Blnk Cnt1 Eye Blink Counter
Eye Tracker #2
.Pupil.H2........ PRM_PUPILH2 Pupil H2 Eye Pupil Horizontal Center Position
.Pupil.V2........ PRM_PUPILV2 Pupil V2 Eye Pupil Vertical Center Position
.Pupil.D2........ PRM_PUPILD2 Pupil D2 Eye Pupil Horizontal Diameter
.Pupil.VD2....... PRM_PUPILVD2 Pupil VD2 Eye Pupil Vertical Diameter
.Pupil.A2........ PRM_PUPILA2 Pupil A2 Eye Pupil Area
.C.R..H2......... PRM_CRH2 C.R. H2 Eye Corneal Reflection Horiz. Position
.C.R..V2......... PRM_CRV2 C.R. V2 Eye Corneal Reflection Vertical Position
.P-CR.H2......... PRM_PCRH2 P-C.R. H2 Eye Pupil to Corneal Refl. Horiz. Difference
.P-CR.V2......... PRM_PCRV2 P-C.R. V2 Eye Pupil to Corneal Refl. Vertical Difference
.Blink.St2....... PRM_BLNKST2 Blnk St2 Eye Blink Status
.Blink.Cnt2...... PRM_BLNKCT2 Blnk Cnt2 Eye Blink Counter
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Section 8: Graph Display Controls
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Parameter Label Parameter (.dqw) Param (.tda) Description
Eye Tracker #3
.Pupil.H3........ PRM_PUPILH3 Pupil H3 Eye Pupil Horizontal Center Position
.Pupil.V3........ PRM_PUPILV3 Pupil V3 Eye Pupil Vertical Center Position
.Pupil.D3........ PRM_PUPILD3 Pupil D3 Eye Pupil Horizontal Diameter
.Pupil.VD3....... PRM_PUPILVD3 Pupil VD3 Eye Pupil Vertical Diameter
.Pupil.A3........ PRM_PUPILA3 Pupil A3 Eye Pupil Area
.C.R..H3......... PRM_CRH3 C.R. H3 Eye Corneal Reflection Horiz. Position
.C.R..V3......... PRM_CRV3 C.R. V3 Eye Corneal Reflection Vertical Position
.P-CR.H3......... PRM_PCRH3 P-C.R. H3 Eye Pupil to Corneal Refl. Horiz. Difference
.P-CR.V3......... PRM_PCRV3 P-C.R. V3 Eye Pupil to Corneal Refl. Vertical Difference
Eye Tracker #4
.Pupil.H4........ PRM_PUPILH4 Pupil H4 Eye Pupil Horizontal Center Position
.Pupil.V4........ PRM_PUPILV4 Pupil V4 Eye Pupil Vertical Center Position
.Pupil.D4........ PRM_PUPILD4 Pupil D4 Eye Pupil Horizontal Diameter
.Pupil.VD4....... PRM_PUPILVD4 Pupil VD4 Eye Pupil Vertical Diameter
.Pupil.A4........ PRM_PUPILA4 Pupil A4 Eye Pupil Area
.C.R..H4......... PRM_CRH4 C.R. H4 Eye Corneal Reflection Horiz. Position
.C.R..V4......... PRM_CRV4 C.R. V4 Eye Corneal Reflection Vertical Position
.P-CR.H4......... PRM_PCRH4 P-C.R. H4 Eye Pupil to Corneal Refl. Horiz. Difference
.P-CR.V4......... PRM_PCRV4 P-C.R. V4 Eye Pupil to Corneal Refl. Vertical Difference
Eye Trigger State
.Eye.Trig.0...... PRM_EYETRIG0 EyeTrig 0 Eye Trigger Status (Each Bit = 1 Trig State)
Point-of-Regard (P.O.R.) Calibrator #1
.POR.H1A......... PRM_PORH1A POR H1A Eye P.O.R. Horiz. Position (Source A)
.POR.V1A......... PRM_PORV1A POR V1A Eye P.O.R. Vertical Position (Source A)
.POR.RH1A....... PRM_POR_RH1A POR RwH1A Eye P.O.R. Raw Horiz. Position (Source A)
.POR.RV1A....... PRM_POR_RV1A POR RwV1A Eye P.O.R. Raw Vertical Position (Source A)
.POR.H1B......... PRM_PORH1B POR H1B Eye P.O.R. Horiz. Position (Source B)
.POR.V1B......... PRM_PORV1B POR V1B Eye P.O.R. Vertical Position (Source B)
.POR.RV1B....... PRM_POR_RH1B POR RwH1B Eye P.O.R. Raw Horiz. Position (Source B)
.POR.RV1B....... PRM_POR_RV1B POR RwV1B Eye P.O.R. Raw Vertical Position (Source B)
.POR.Mode1...... PRM_PORMODE1 POR Mode1 POR Mode of Operation (Reset/Calib/Output)
.POR.Hrs.1....... PRM_PORHRS1 POR Hrs1 Calibrator Video Data Display - Hours Value
.POR.Mins1...... PRM_PORMINS1 POR Mins1 Calibrator Video Data Display - Minutes Value
.POR.Secs1...... PRM_PORSECS1 POR Secs1 Calibrator Video Data Display - Seconds Value
.POR.Frms1...... PRM_PORFRMS1 POR Frms1 Calibrator Video Data Display - Frames Value
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Parameter Label Parameter (.dqw) Param (.tda) Description
Point-of-Regard (P.O.R.) Calibrator #2
.POR.H2A......... PRM_PORH2A POR H2A Eye P.O.R. Horiz. Position (Source A)
.POR.V2A......... PRM_PORV2A POR V2A Eye P.O.R. Vertical Position (Source A)
.POR.RH2A....... PRM_POR_RH2A POR RwH2A Eye P.O.R. Raw Horiz. Position (Source A)
.POR.RV2A....... PRM_POR_RV2A POR RwV2A Eye P.O.R. Raw Vertical Position (Source A)
.POR.H2B......... PRM_PORH2B POR H2B Eye P.O.R. Horiz. Position (Source B)
.POR.V2B......... PRM_PORV2B POR V2B Eye P.O.R. Vertical Position (Source B)
.POR.RH2B....... PRM_POR_RH2B POR RwH2B Eye P.O.R. Raw Horiz. Position (Source B)
.POR.RV2B....... PRM_POR_RV2B POR RwV2B Eye P.O.R. Raw Vertical Position (Source B)
.POR.Mode2...... PRM_PORMODE2 POR Mode2 POR Mode of Operation (Reset/Calib/Output)
.POR.Hrs.2....... PRM_PORHRS2 POR Hrs2 Calibrator Video Data Display - Hours Value
.POR.Mins2...... PRM_PORMINS2 POR Mins2 Calibrator Video Data Display - Minutes Value
.POR.Secs2...... PRM_PORSECS2 POR Secs2 Calibrator Video Data Display - Seconds Value
.POR.Frms2...... PRM_PORFRMS2 POR Frms2 Calibrator Video Data Display - Frames Value
Head Tracker Input Parameters
.Head.X......... PRM_HEAD_X Head X Head X Position (in.)
.Head.Y......... PRM_HEAD_Y Head Y Head Y Position (in.)
.Head.Z......... PRM_HEAD_Z Head Z Head Z Position (in.)
.Head.Azim...... PRM_HEAD_AZ Head Azim Head Azimuth Angle (deg.)
.Head.Elev...... PRM_HEAD_EL Head Elev Head Elevation Angle (deg.)
.Head.Roll...... PRM_HEAD_RO Head Roll Head Roll Angle (deg.)
Auxiliary Serial Input Parameters
.Serial.In.0..... PRM_SERINP0 Ser Inp 0 Auxiliary Serial Input Byte
Auxiliary Digital Input Parameters
.Digit.In.1A.... PRM_DIGIN1A Dig Inp 1A Auxiliary Digital Input Byte (Card 1, Port A)
.Digit.In.1B.... PRM_DIGIN1B Dig Inp 1B Auxiliary Digital Input Byte (Card 1, Port B)
.Digit.In.1C.... PRM_DIGIN1C Dig Inp 1C Auxiliary Digital Input Byte (Card 1, Port C)
.Digit.In.2A.... PRM_DIGIN2A Dig Inp 2A Auxiliary Digital Input Byte (Card 2, Port A)
.Digit.In.2B.... PRM_DIGIN2B Dig Inp 2B Auxiliary Digital Input Byte (Card 2, Port B)
.Digit.In.2C.... PRM_DIGIN2C Dig Inp 2C Auxiliary Digital Input Byte (Card 2, Port C)
.Digit.In.3A.... PRM_DIGIN3A Dig Inp 3A Auxiliary Digital Input Byte (Card 3, Port A)
.Digit.In.3B.... PRM_DIGIN3B Dig Inp 3B Auxiliary Digital Input Byte (Card 3, Port B)
.Digit.In.3C.... PRM_DIGIN3C Dig Inp 3C Auxiliary Digital Input Byte (Card 3, Port C)
.Digit.In.4A.... PRM_DIGIN4A Dig Inp 4A Auxiliary Digital Input Byte (Card 4, Port A)
.Digit.In.4B.... PRM_DIGIN4B Dig Inp 4B Auxiliary Digital Input Byte (Card 4, Port B)
.Digit.In.4C.... PRM_DIGIN4C Dig Inp 4C Auxiliary Digital Input Byte (Card 4, Port C)
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Section 8: Graph Display Controls
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Parameter Label Parameter (.dqw) Param (.tda) Description
Auxiliary Digital Output Parameters
.DigitOut.1A.... PRM_DIGOUT1A DigOut 1A Auxiliary Digital Output Byte (Card 1, Port A)
.DigitOut.1B.... PRM_DIGOUT1B DigOut 1B Auxiliary Digital Output Byte (Card 1, Port B)
.DigitOut.1C.... PRM_DIGOUT1C DigOut 1C Auxiliary Digital Output Byte (Card 1, Port C)
.DigitOut.2A.... PRM_DIGOUT2A DigOut 2A Auxiliary Digital Output Byte (Card 2, Port A)
.DigitOut.2B.... PRM_DIGOUT2B DigOut 2B Auxiliary Digital Output Byte (Card 2, Port B)
.DigitOut.2C.... PRM_DIGOUT2C DigOut 2C Auxiliary Digital Output Byte (Card 2, Port C)
.DigitOut.3A.... PRM_DIGOUT3A DigOut 3A Auxiliary Digital Output Byte (Card 3, Port A)
.DigitOut.3B.... PRM_DIGOUT3B DigOut 3B Auxiliary Digital Output Byte (Card 3, Port B)
.DigitOut.3C.... PRM_DIGOUT3C DigOut 3C Auxiliary Digital Output Byte (Card 3, Port C)
.DigitOut.4A.... PRM_DIGOUT4A DigOut 4A Auxiliary Digital Output Byte (Card 4, Port A)
.DigitOut.4B.... PRM_DIGOUT4B DigOut 4B Auxiliary Digital Output Byte (Card 4, Port B)
.DigitOut.4C.... PRM_DIGOUT4C DigOut 4C Auxiliary Digital Output Byte (Card 4, Port C)
Auxiliary Analog Input Parameters
.Anlg.In.1...... PRM_ANLGIN1 Anlg Inp 1 Auxiliary Analog Input #1 - Value
.Anlg.In.2...... PRM_ANLGIN2 Anlg Inp 2 Auxiliary Analog Input #2 - Value
.Anlg.In.3...... PRM_ANLGIN3 Anlg Inp 3 Auxiliary Analog Input #3 - Value
.Anlg.In.4...... PRM_ANLGIN4 Anlg Inp 4 Auxiliary Analog Input #4 - Value
.Anlg.In.5...... PRM_ANLGIN5 Anlg Inp 5 Auxiliary Analog Input #5 - Value
.Anlg.In.6...... PRM_ANLGIN6 Anlg Inp 6 Auxiliary Analog Input #6 - Value
.Anlg.In.7...... PRM_ANLGIN7 Anlg Inp 7 Auxiliary Analog Input #7 - Value
.Anlg.In.8...... PRM_ANLGIN8 Anlg Inp 8 Auxiliary Analog Input #8 - Value
Eye Tracker #1 - Eye Angle Output Parameters (After Eye Angle Calibration)
.Eye.Azim.1....... PRM_EYE_AZ1 Eye AZ1 Eye Azimuth Angle (deg.)
.Eye.Elev.1....... PRM_EYE_EL1 Eye EL1 Eye Elevation Angle (deg.)
Eye Tracker #2 - Eye Angle Output Parameters (After Eye Angle Calibration)
.Eye.Azim.2....... PRM_EYE_AZ2 Eye AZ2 Eye Azimuth Angle (deg.)
.Eye.Elev.2....... PRM_EYE_EL2 Eye EL2 Eye Elevation Angle (deg.)
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Section 8: Graph Display Controls
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Parameter Label Parameter (.dqw) Param (.tda) Description
Head Tracking Parameters
.LOS.Org.X1....... Origin of Line-of-Sight Vector X
.LOS.Org.Y1....... Origin of Line-of-Sight Vector Y
.LOS.Org.Z1....... Origin of Line-of-Sight Vector Z
.LOS.Vect.X1....... X Component of the Directional Vector of the LOS
.LOS.Vect.Y1....... Y Component of the Directional Vector of the LOS
.LOS.Vect.Z1....... Z Component of the Directional Vector of the LOS
.LOS.Azim.1....... LOS Angle Azimuth
.LOS.Elev.1....... LOS Angle Elevation
PlnInt.X1....... X Coordin. of the Plane Intersection (in World Space)
PlnInt.Y1....... Y Coordin. of the Plane Intersection (in World Space)
PlnInt.Z1....... Z Coordin. of the Plane Intersection (in World Space)
PlnInt.H1....... Plane Int. Horiz. Coordinates in Plane Space 0-511
PlnInt.V1....... Plane Int. Vert. Coordinates in Plane Space 0-511
PlnInt.AvgH1....... Averaged Version of Above
PlnInt.AvgV1....... Averaged Version of Above
VDU.H2A....... XY Horizontal Location over VDUA
VDU.V2A....... XY Vertical Location over VDUA
VDU.H2B....... XY Horizontal Location over VDUB
VDU.V2B....... XY Vertical Location over VDUB
VDU.Hrs.2....... Hours Displayed on VDU Data Bar
VDU.Mins.2....... Minutes Displayed on VDU Data Bar
VDU.Secs.2....... Seconds Displayed on VDU Data Bar
VDU.Frms.2....... Frms Displayed on VDU Data Bar
Active.Run....... Which Run is Being Recorded
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ISCAN ETL-600 Instructions
81 Section 9: LSW Software Features
Section 9: LSW Software Features and Functions
No description of ISCAN’s LSW software can be quite complete, as ISCAN continuously
works to add functions and improvements requested by researchers and system users. The
basic LSW software incorporates many different eye tracking functions, with the most
frequently used discussed in this section, as outlined below:
(A) A blink monitoring subsystem that registers and outputs blinks and can count the
number of blinks over a specified period of time;
(B) Analog outputs, consisting of three ±5VDC analog output channels with the
capability to expand to six analog output channels;
(C) Serial I/O, consisting of three serial ports for data input and output in real time;
(D) Digital I/O, consisting of four TTL digital inputs and four TTL digital outputs that
can be operator-configured for recording control, output of fixation signals, input of
marker pulses, and synchronization signals;
(E) Data recording capability to record up to two hours of 240 Hz, four hours of 120 Hz,
or eight hours of 60 Hz eye position data for post processing via Matlab or Excel.
Detailed descriptions of these functions follow.
Part A: Blink Monitoring
The ETL-600 has a built-in blink detection and counting feature. The detection algorithm
requires that the system operator set a template of the eye with the pupil fully visible to
the eye camera and the pupil position clearly tracked by the eye tracker.
The blink monitor subsystem continuously compares the incoming real time pupil extent
information to that of the template initially set by the operator. It then registers and
counts blinks based on a percentage of eye closure parameter, also operator selectable.
The blink state is represented by the graph parameter BlinkSt1 and is a digital “0” when
the eye is open and a digital “1” when the eye is closed (beyond the percentage of eye
closure setting).
The blink count is represented by the graph parameter BlinkCnt1 and is a real time
integer representing the number of blinks that have occurred since the template was set.
The operator can clear the blink count at any time manually or can enable a feature that
automatically clears the blink count at the start of a data recording episode.
To enable blink monitoring, disable Track Active in the LSW software and click on the
“Fork & Spoon” configuration icon [Figure 4.1 (9)] to display the ISCAN system
configuration panel. Click on the Blink/Fixation tab, and set the blink criteria in that
panel as shown in Figure 9.1 below:
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82 Section 9: LSW Software Features
Figure 9.1: Blink Monitor Configuration Panel
Enable the blink monitor, and set the percentage of eye closure to the desired level. In this
example it is set to 80%. This means that if 80% or more of the pupil size is obscured or
has disappeared, the subject has blinked. Enabling Clear Blink Count w/Record will reset
the blink count automatically to zero at the beginning of a recording event.
Click OK to return to the LSW window. Enable Track Active, and note the blink controls
that are now highlighted at the bottom of the eye tracker controls panel in the upper left
hand side of the LSW window.
Figure 9.2: Blink Controls Enabled
Have the subject fixate straight ahead and ensure that the eye landmarks are properly
tracked. Click on the Set button in the blink control panel.
ISCAN ETL-600 Instructions
83 Section 9: LSW Software Features
Figure 9.3: Blink Control Panel
This captures a pupil extent template, based on the pupil size parameters calculated by
the eye tracking processor. Load the BlinkSt1 and BlinkCnt1 parameters into the graph
display, if desired. At the subject’s eye closes during a blink, the BlinkSt1 will change from
a “0” to a “1,” and the BlinkCnt1 number will increment by one integer.
Clicking on the Clear button in the blink control panel will set the blink count number to
zero.
The blink state and blink count monitoring can be selected for recording and/or real time
output via the digital outputs (see Section 9, Part D), analog outputs (see Section 9, Part
B), or serial ports outputs (see Section 9, Part C).
ISCAN ETL-600 Instructions
84 Section 9: LSW Software Features
Part B: ISCAN Analog Outputs
The ETL-600 normally has three analog outputs. The outputs are generally assigned to
Pupil or Pupil – Corneal Reflection horizontal position, Pupil or Pupil – C.R. vertical
position, and pupil size, either horizontal or vertical diameter or pupil area. The output
range of the analog outputs is ±5 volts DC.
Selecting Analog Outputs
The ETL-600 is shipped with the three analog outputs enabled. Clicking through the
Options button will bring up the Auxiliary Output Control panel in the lower left hand
corner of the LSW Control Window.
The analog folder should be configured as shown in Figure 9.4 below:
Figure 9.4: Analog Output Control Panel
Clicking on the Parameter Control box to the right of the parameter selects and loads a
desired analog output parameter.
Double-clicking on the highlighted parameter selects that parameter as an analog output.
Figure 9.5: Select Analog Output Parameters
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85 Section 9: LSW Software Features
It is also important to add the same analog output parameters to the graph displays. For
example, if you have selected PupilH1, the pupil horizontal position, as an analog output,
make sure to add PupilH1 into one of the graph displays. This will allow for scaling of the
selected analog outputs over the ±5VDC range. See this example in Figure 9.6 below.
Figure 9.6: Analog Output Parameters & Graph Displays
See Section 8 for a detailed discussion of scaling the analog outputs.
ISCAN ETL-600 Instructions
86 Section 9: LSW Software Features
Configuring the Analog Outputs
With Track Active disabled, click on the “Fork & Spoon” configuration icon [Figure 4.1 (8)],
then click on the Analog I/O tab to show the Analog Inputs and Outputs control panel as
shown in Figure 9.7 below.
Figure 9.7: Analog Inputs & Outputs Control Panel
Set the Analog Outputs so Output Active is checked, the Card Type is RK8X6PCI-0, and
the Volt Range is ±5VDC.
Click on OK to exit from the System Configuration window display.
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87 Section 9: LSW Software Features
Part C: Serial I/O
The ETL-600 eye tracking computer has three RS-232 serial ports labeled COM1, COM2
and COM3. These serial ports can receive and transmit RS-232 format data at rates up to
115K bytes/second (baud). In the ETL-600, the COM1 port is always dedicated to the head
tracker. Use COM2 or COM3 for external data communications.
IMPORTANT: always use a null modem serial cable when using the serial ports to
transfer data. A null modem cable has the data transmit pin on one end connected to the
data receive pin on the other so serial data transfer can be performed. The biggest problem
associated with a serial port data transmission is the failure to use a null modem cable.
Example of How to Use Serial Port
Connect a null modem serial cable into the COM2 port of the ISCAN eye tracking
computer.
Open the ISCAN LSW software, and with Track Active disabled click on the “Fork &
Spoon” configuration icon [Figure 4.1 (9)]. When the ISCAN System Configuration panel
appears, click on the Serial I/O tab. The Serial I/O configuration panel will appear as
shown in Figure 9.8 below.
Figure 9.8: Serial I/O Configuration Panel
Select Data I/O-0 in the COM2 port, a Baud rate of 57,600 or 115,200, and Output Active
for data output only. Enable Input Active only if data is being sent to the ISCAN eye
tracker computer.
Click OK to close the System Configuration panel.
Click on the Options button until the Serial controls appear in the Auxiliary Output
Controls panel, as in Figure 9.9 below.
ISCAN ETL-600 Instructions
88 Section 9: LSW Software Features
Figure 9.9: Serial Output Controls Panel
Set the Data parameter to Raw…ASCII or Raw…Binary, depending on the type of output
data format required. See Section 14 Appendix A for more detail regarding the
ASCII/binary formats.
The data may also be selected as Scaled…ASCII or Scaled…Binary. These settings allow
for the serial output to be scaled just like the analog outputs, under graph control. See
Section 8 for a detailed discussion of scaling the analog outputs
Load the desired eye parameters to be output into the data boxes labeled 01 to 06. Note
that there are two available parameter banks that can be loaded with up to twelve
parameters in total. In the example shown in Figure 9.9, PlnInt.Num1, PlnInt.AvgH1, and
PlnInt.AvgV1 are loaded into Banks 01, 02, and 03 respectively.
Click on Track Active to enable serial output. With the other end of the null modem cable
hooked up to a data acquisition computer running a standard serial interface program
such as Hyperterminal or TeraTerm, the serial link can be confirmed and any
transmission or data format problems resolved. Make sure that the baud rate of the
receiving program matches the baud rate set in the ISCAN serial configuration panel.
Make sure that the data format in the receiving program is set to ASCII or binary, the
same as in the ISCAN data output format, and that a null modem cable is used.
For a more technically detailed discussion of serial data formats and ISCAN software
controls, see Section 14 Appendix A.
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Part D: Digital I/O
The ETL-600 comes with a digital interface that contains four TTL inputs and four TTL
outputs. The TTL signal is OVDC digital low or “0” or +5 digital high or “1.”
The four TTL inputs and outputs are located on the 9-pin D-sub female connector on the 3-
analog output card, installed in the eye tracker PC. See Figure 3.2.
The pin-out of the digital I/O connector is shown in Figure 9.10 below.
Figure 9.10: ISCAN Digital I/O Connector
For normal ETL-600 applications, the digital I/O is configured for four separate input and
four separate output TTL lines.
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90 Section 9: LSW Software Features
With the Track Active disabled, click on the “Fork & Spoon” configuration icon [Figure 4.1
(9)]. When the ISCAN System Configuration panel appears, click on the Digital I/O tab.
The Digital I/O configuration panel will appear as shown in Figure 9.11 below.
Figure 9.11: Digital I/O Configuration Panel
These are the default settings for ISCAN’s digital I/O card. Click on OK to return to the
main LSW software window.
Click on the Options button to bring up the Auxiliary Output Controls panel as shown in
Figure 9.12 below.
Figure 9.12: Digital Output Controls Panel
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91 Section 9: LSW Software Features
Each of the four available output bits, digital bit 0, 1, 2, and 3, can be assigned a variety of
outputs. Click on the down arrow to the right of the Bit0 alphanumeric display box and a
drop-down list of available digital outputs parameters appears for selection as shown in
Figure 9.13 below.
Figure 9.13: Digital Output Bit Selection
In all cases Track Active must be enabled to have the digital data appear at output.
Manual:
Allows the operator to test the digital output line by manually toggling the bit high
or low by clicking on the H or L button next to the alphanumerical box. Track
Active must be enabled for the digital data to appear at the appropriate output.
Sync:
The sync output generates a TTL level sync pulse on the digital output line that is
synchronous with the vertical sync pulse of the eye camera. The sync pulse is
normally TTL low and goes high every V-Sync pulse.
Trig1A, B, C, D:
Selecting Trig1A, Trig1B, Trig1C, or Trig1D routes the selected Trigger1 signal to
the digital output. The trigger signal is associated with a Fixation Monitoring
subsystem that is not applicable to the ETL-600.
Trig2A, B, C, D:
As above, but routes the selected Trigger2 signal to the selected digital output.
Blink St1:
Selecting Blink St1 routes the blink state output (digital 0 if eye is open, digital 1
if eye is closed/blinking).
Record St:
Selecting Record St1 routes the data recording status out the selected digital port.
The recording state is low (digital 0) during recording and high (digital 1) when
recording has stopped.
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92 Section 9: LSW Software Features
Part E: Recording Data
The ETL-600 is configured to record up to 24 digital eye parameters simultaneously. The
recording function can be controlled by the PC mouse, serial commands, an external
switch, or via a TTL digital input.
A single data run is defined as one cycle of starting and stopping recording. The system
operator can set a limit to the number of runs that can be consecutively recorded and also
set a number of data points that can be recorded in a single run. The number of data
points depends upon the sample speed of the eye position data.
At 60 Hz, 60 data points are recorded every second, resulting in 3600 data points each
minute. If the number of points per run is set at 7200 with a Runs limit of 10, this results
in ten two-minute recordings.
The ETL-600 may also be configured with a 120/240 Hz high-speed eye tracker. With this
option:
At 120 Hz, 120 data points are recorded every second, resulting in 7200 data points each
minute. If the number of points per run is set at 7200 with a Runs limit of 10, this results
in ten one-minute recordings.
At 240 Hz, 240 data points are recorded every second, resulting in 14,400 data points each
minute. If the number of points per run remains set at 7200, with a runs limit of 10, this
results in ten 30-second recordings.
It is important to calculate a priori the expected length of time for recording and the
expected number of data points, and take into account the 120 or 240 Hz sampling
frequency.
The maximum number of data points that can be recorded by the standard ETL-600 is
2,000,000. This would result in a maximum continuous recording of just over 2 hours at
240 Hz, about 4! hours at 120 Hz, and about 8 to 9 hours at 60 Hz.
The Data Recording controls are in the lower left hand side of the LSW window, as shown
in Figure 9.14 below.
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93 Section 9: LSW Software Features
Figure 9.14: Data Recording Control Panel
In the example above, the sampling rate of the eye tracker is 120 Hz, and recording is set
for Internal, meaning a mouse click can be used to start recording. The Runs Limit is set
to 10, and the number of Points per Run is set to 20,800.
Clicking on the Bank 1 tab in the Data Recording Controls panel brings up the display of
the parameters that the operator has loaded for recording.
Figure 9.15: Data Recording Parameters Bank
There are three banks that can hold eight different parameters, resulting in a maximum
of 24 discrete parameters that can be recorded in each run. Clicking on the box to the right
of a parameter shows the drop-down list of all available data that can be loaded in for
recording. Double-click on the highlighted parameter on the list to enter it into the
alphanumeric display box as demonstrated above. The list of available parameters is
shown at the end of Section 8.
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94 Section 9: LSW Software Features
Recording Configuration Panel
To customize the recording for a specific application, disable Track Active and click on the
“Fork & Spoon” configuration icon [Figure 4.1 (8)] to bring up the system configuration
panels, then click on the Recording tab to display the Recording Configuration panel as
shown in Figure 9.16 below:
Figure 9.16: Recording Configuration Panel
(1) Recording Trigger: Internal, Serial, Switch, or Digital
(2) Sample Mode: All Points or ! Points
(3) Source: None, RK-8x6PCI-0, RK-632-PCI-0, or Par Port-0
(4) Lockout Samples:
(5) Trigger Edge: Leading or Trailing
(6) Points/Run Action: Stop Recording or Start New Run
(7) Points Run Limit
(8) Maximum Data Runs
(9) Maximum Data Points
(10) Toggle Data Bar
The Recording Trigger (1) is normally set to Internal. Internal allows for the starting and
stopping of data recording via the PC mouse.
Set the Recording Trigger to Serial mode for starting and stopping the recording via the
hex serial commands (Section 14, Appendix A).
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95 Section 9: LSW Software Features
Set the Recording Trigger to Switch mode if a pushbutton switch is used to enable
recording. Hook the switch up between Pins 1 and 9 on the ISCAN digital I/O 9-pin D-SUB
connector. Pin 1 is the switch input and Pin 9 is Ground (Figure 9.10).
Set the Recording Trigger to Digital if an external TTL digital signal is required to start
and stop recording. Recording starts with an active “low” (digital 0) TTL signal and stops
when it turns “high” (digital 1). Hook the digital TTL signal to Pin 1 of the 9-pin D-SUB
I/O connector and ground to Pin 9 (Figure 9.10).
The Sample Mode (2) is normally set to record all Points, but allows the operator to record
Half Points. In the ! Points mode, every other data point is recorded.
The Switch Trigger configurations are only used if the Switch mode has been enabled as
the Recording Trigger. Switch Trigger Source (3) may be any of the three active sources
listed above, and each is described in detail below:
Setting the Switch Trigger Source to RK-8xPCI-0 allows a switch to be connected
on Pin 1 of the 9-pin D-Sub female digital input connector on the back of the eye
tracker PC. Pin 9 of the 9-pin D-Sub connector is ground.
Setting the Switch Trigger Source to RK-632PCI-0 can only be done if an ISCAN
RK-630PCI calibration card has been installed in the ETL-600.
Setting the Switch Trigger Source to Par Port-0 allows a switch to be connected to
the PC parallel printer port on the back of the eye tracker PC between Pin 10 and
Pin 25. Pin 10 is the switch signal input, and Pin 25 is ground on the PC parallel
printer port.
Lockout Samples (4) is the amount of video fields during which a second switch slick is
ignored.
Trigger Edge (5) can be selected for the leading or trailing edge of the switch pulse to start
or stop recording.
The Points/Run Action (6) can be configured to Stop Recording or set to Start New Run.
The Points Run Limit (7) can be set to the maximum number of points expected in a single
run. After the limit has been reached, the recording automatically stops. This number also
is displayed in the LSW data recording control display.
The maximum number of data runs (8) is set at 400, and the maximum number of data
points (9) is set at 2 million. The system operator cannot change either of these limits.
The Toggle Data Bar (10) function is normally disabled.
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96 Section 9: LSW Software Features
Example of Recording and Reading Data
With the LSW window open and Track Active enabled, obtain a clear, trackable image of
the eye. Click on Start Record and after a short time, click on Stop Record.
The Pts Rec’d shows how many data points were recorded. In the example shown in Figure
9.17 below, there were 1022 data points recorded.
Figure 9.17: Data Recording Controls Info
The Delete All and Delete Last buttons are enabled after completion of a recording run.
Click on Delete All to delete all of the runs that may have been recorded. Click on Delete
Last to delete just the previous recorded run.
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97 Section 9: LSW Software Features
Disable Track Active. Click on File [Figure 4.1 (14)] in the LSW software window, and
scroll down to select Save ISCAN ASCII Data File as tab-delimited ASCII (TDA), as
shown in Figure 9.18 below.
Figure 9.18: Save TDA Data in File
The recorded data run will automatically be saved to the Documents folder in the PC.
Make sure to label the run as a .TDA file. In this example it is called Test.TDA, as shown
in Figure 9.19 below.
Figure 9.19: Saving Data as Test.TDA
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98 Section 9: LSW Software Features
Open the Documents folder in Windows, and verify that it has been saved as Test.TDA.
To open and view the data, use the WordPad application in the eye tracker PC. To find
Word Pad, click on the Windows Start Menu icon, scroll to Accessories, and click on
WordPad, as shown in Figure 9.20 below. When WordPad starts up, click on Open File,
and make sure that All Documents is selected in order to see all the .TDA files, as shown
in Figure 9.20 below.
Figure 9.20: Open WordPad
Double-click on your data file (in this example, Test.TDA) to open the file and view the
data. WordPad will format the data as shown in Figure 9.21 below.
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99 Section 9: LSW Software Features
Figure 9.21: Test.TDA Data
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101 Section 10: Recording Data for PRZ
Section 10: Recording Data for Analysis by the ISCAN PRZ Software
When using the global view scene camera to capture an image of the subject’s work area, it
may be of interest to record the X and Y locations of the subject’s line of sight intersection
with the planar surfaces, and automatically analyze the fixation data with the ISCAN
PRZ analysis software.
The VDU.H2A and VDU.V2A parameters represent the location of the horizontal and
vertical gaze point of the subject, superimposed over the global view monitor area.
First, load the VDU.H2A and VDU.V2A parameters into the Data Recording Controls
panel. To do this, disable Track Active, and click on the Bank 1 tab in the Data Recording
Controls panel. Select the VDU.H2A and VDU.V2A for recording by clicking on the
selection boxes, as shown in Figure 10.1.
Figure 10.1: Loading VDU.H2A and VDU.V2A into Bank 1
The ISCAN PRZ software will read this gaze point data from a fixation file created by the
operator and the PRZ software will correlate the gaze point with the location of the planar
surfaces that were registered by the operator onto the image of the global view scene.
The operator can also take a digital photo of the subject’s scene field of view (similar to
that seen by the global view camera) and import this image as a bitmap into the PRZ
analysis software. The operator will also register four clearly identifiable features in this
new scene image, to “anchor” or match up the bitmapped image to that of the global view
camera.
Part A: Image Registration for PRZ
A step-by-step description of the image registration procedure for PRZ is as follows:
With Track Active disabled, click on the Options button until the Video Display Unit
Controls panel appears. Alternatively, click on the enlarge button for the global view
monitor, and the VDU Controls panel will come up automatically.
The Video Display Unit Controls panel contains three operator-selectable options: Single
Plane mode, Global View mode, and Image Registration mode.
Click on the Image Registration button as shown in Figure 10.2.
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102 Section 10: Recording Data for PRZ
Figure 10.2: Image Registration, Upper Left
The four registration or anchor points will be visible in the gray pseudo-screen area, and
the upper left point will be circled. Click on the upper left point and drag it until the
associated indicator in the global view monitor is superimposed over an unambiguous
visible point on that monitor. In the example shown in Figure 10.3 below (a series of
screen shots), the operator places the four registration points on the upper left and lower
left corners of Plane 3, and the upper right and lower right corners of Plane 2.
Figure 10.3: Defining the Anchor Points
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103 Section 10: Recording Data for PRZ
Once the upper left point is satisfactorily superimposed over a clearly definable target in
the global view image, release the mouse button to register the anchor point. Click on the
up or down arrow of the Active Item box to select the next point. Repeat the above
procedure for the upper right, lower left, and lower right registration points as shown in
Figure 10.3. The X and Y coordinates of each of these registration points are stored in the
fixation file that is described below, and are used to anchor the bitmapped image of the
subject’s work space to the global view monitor image, when using the PRZ analysis
software.
Part B: Recording a Data Run
Enable Track Active, set up the subject with the headgear, perform the eye angle
calibration (see Section 7), and press the Start Record button to record a data run, as
shown in Figure 10.4.
Figure 10.4: Start Recording
After the run is completed, click Quit Record. See Figure 10.5
Figure 10.5: Quit Recording
ISCAN ETL-600 Instructions
104 Section 10: Recording Data for PRZ
Part C: Storing the Eye/Head Plane Intersection Data in a Fixation File
Disable Track Active and click on the File menu. Select the drop-down “Save ISCAN
P.O.R. Fixation File As …” in the menu as shown in Figure 10.6.
Figure 10.6: Select Save Fixation File
The ISCAN P.O.R. Fixation file info box will open as shown in Figure 10.7 below.
Figure 10.7: Open Fixation File
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105 Section 10: Recording Data for PRZ
Click on Continue, and enter a new ID# from between 100 and 200, and a Track ID, either
lower case n or letters a through f, as shown in Figure 10.8
Figure 10.8: Identifying a Fixation File
Click on Finish, and the “Save P.O.R Fixation File As” box will appear. Save the Fixation
file as a .fxn file. In the example below, it is called test.fxn, and it is saved in the
LSW1_00T folder, as shown in Figure 10.9.
Figure 10.9: Saving a Fixation File
After keying in test.fxn, click on the Save button, and the LSW Control screen will be
visible. The .fxn fixation data file will be recalled for analysis by the ISCAN PRZ program.
Running the ISCAN PRZ Advanced Analysis Program
The PRZ software will read the .fxn file and perform automated fixation analysis, generate
scan path data, and allow the operator to elicit various metrics from the eye and head
position intersection data.
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107 Section 11: PRZ Overview
Section 11: PRZ Overview
One of the principal uses of eye tracking technology is to determine precisely where on a
stimulus or target image, a subject has fixated and to analyze the fixation patterns. To
make sense of the fixation data, it is essential to correlate fixations with the particular
image being seen and objects of importance within this image. In addition, it is often of
value to consolidate the resulting data over multiple trials and/or multiple subjects. The
ISCAN Point-of-Regard Analysis (PRZ) Software implements a methodology that allows
users to automate the fixation analysis process and report results.
Features of the software include:
# Image registration to allow data from different data collection and stimulus
presentation contexts to be combined;
# Creation of image sequences to define stimulus viewing order;
# Definition of elements of interest via easy-to-use drawing tools with full editing
controls;
# Ability to aggregate elements into “nets;”
# Seamless integration with ISCAN’s Raw Eye Movement Data Acquisition Software
(DQW);
# Analysis of each individual view of the stimulus images including scan paths and
data tables;
# Combined analysis of groups of subjects and/or groups of images including
population-based data tables and charts (professional version only).
Task Configuration
In order to properly make use of the PRZ methodology, the user must first identify the
scope of the study, the context in which stimuli will be presented, the particular stimulus
images to be used and the key elements within the images to be tested.
Scope and Study Context
The PRZ software has primarily been designed to accommodate studies in which one or
many still images are presented in sequence to a subject while their eye movements are
being monitored. Usually this is in the context of subjects seated and remotely viewing a
single fixed display, but head-mounted VR displays, multi-monitor environments, and
video stimulus presentations can also be analyzed. The PRZ methodology allows the
fixation data to be accurately consolidated even if an image is presented in more than one
context.
Stimulus Images
Depending on the image stimuli required or desirable for different studies, various image
formats, resolutions and display sizes may b e employed. For the purposes of stimulus
presentation, any images compatible with the chosen display context are acceptable, but it
is advisable to use the same image format and resolution for all of the images within any
particular study.
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108 Section 11: PRZ Overview
The PRZ software accepts image files in the BMP format only, but can accommodate any
resolution image in this format. The BMP format is used because it is found globally and
is completely loss-less. If the study context requires presentation of images in a format
other than BMP, a simple conversion process in any graphics program can be used to
produce an analogous set of BMP images for use in the PRZ program.
An important part of the preliminary work for any study is to determine the display
context and stimuli image characteristics to be used.
Master Registration Image
In addition to the various stimulus images prepared for the study, a master registration
image (MRI) must be created for the display context being employed. The MRI allows data
to be analyzed and consolidated from different subjects even if the image stimuli are
presented in different display contexts.
The MRI is a simple image containing four or five targets. The MRI must be of the same
size and resolution as the other stimulus images to be displayed in the study context. If
five targets are included, this image can also be used in each subject’s eye point-of-regard
calibration when eye data is being collected. As with the other stimulus images, an
analogous MRI in BMP format must be created using the same scaling and/or
reformatting process, for use in the PRZ software.
PRZ/DQW Workflow
The following steps outline the suggested workflow for preparing sets of individual image
stimuli, collecting fixation data and producing results using the PRZ software in
conjunction with ISCAN’s eye movement monitoring systems and data acquisition
software (DQW), as shown in Figure 11.1:
#
ISCAN ETL-600 Instructions
109 Section 11: PRZ Overview
Figure 11.1: PRZ/DQW Workflow Diagram
1. Task Configuration: Complete the task configuration steps described above.
2. Image Registration: In the PRZ software image registration module, combine
each BMP stimulus image with registration points matched with the BMP
master registration image. Create a resulting registered image file (IGR) for
each image.
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110 Section 11: PRZ Overview
3. Image Sequencing: In the PRZ software image sequencing module, create one or
more sequences of registered stimulus images in the order(s) they will be
presented. Generate one or more sequence files (SEQs) to be used by the data
acquisition software.
4. Eye Point-of-Regard Data Collection: Using the DQW software, read in the
appropriate SEQ file generated in Step 3, and collect eye point-of-regard data
from one or more subjects while they view the stimulus images. Generate a
fixation file (FXN) for each subject’s viewing session.
5. Image Element Entry: Read the IGR images into the PRZ program element
entry module, and using the drawing tools outline each of the elements of
interest for the current image. Create “nets” to aggregate image elements for
analysis. Generate one or more element files (EMTs) describing the elements
and nets you’ve created for each image.
6. Individual Analysis: In the PRZ individual analysis module, read an EMT file
and a FXN file in which the subject viewed the image of interest. View and
report image scan paths and data tables scoring eye fixations on the elements
and nets defined.
7. Group Analysis: In the PRZ professional version only, a group analysis module is
available. Here multiple FXNs and EMTs may be grouped and analyzed as a
population. So, for example, where individual analysis will tell you what element
the subject fixated on first, group analysis will tell you what percentage of the
subject population fixated first on each of the elements defined. View and report
group data tables and bar charts.
Please note that Steps 4 and 5 above may be done in any order or in parallel.
Figure 11.2 is a summary table of the various file types discussed in this section.
Figure 11.2: PRZ File Definitions Table
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Section 12: FACTORY.DEF Settings
111
Section 12: Saving & Retrieving Configuration Settings
The LSW software has a multitude of settings, allowing the program to be configured for
many different types of eye tracking applications. On program start up, the software
automatically loads the settings that are stored in a definition file, a file with suffix .def.
This definition file is updated each time the LSW program is closed, saving all parameter
and board changes that may have been made by the operator.
Saving Definition Files
To save a definition file, for a specific subject or to save the settings for those that were
used in a particular experiment, go to the file menu, with Track Active disabled, and click
on the "SAVE DQW SETTINGS FILE as..." as shown in Figure 12.1 below. (Note: the
DQW and LSW may be used interchangeably.)
Figure 12.1: Save LSW Settings
Call the file an easy to remember name, in this example Factory.def, and save it in the
LSW folder, an example of which is shown in Figure 12.2 below.
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Section 12: FACTORY.DEF Settings
112
Figure 12.2: Saving a Unique .def File
Retrieving LSW Settings via Definition Files
To restore the LSW software settings you have previously saved, (i.e to open a settings
file), disable Track Active, click on the File menu and select "Open DQW Settings File" as
shown in Figure 12.3 below.
Figure 12.3: Open LSW Settings in File Menu
When the Open LSW Settings window appears, double click on the desired .def file. In the
example shown in Figure 12.4, factory.def is being selected.
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Section 12: FACTORY.DEF Settings
113
Figure 12.4: Selecting a Saved .def File
The LSW program will now contain all the settings previously saved in the selected .def
file.
Factory Definition File
The Open Settings File window will also contain a factory.def backup file loaded by ISCAN
prior to system shipment. The factory.def file contains all the factory settings when the
ETL-600 was shipped. Double clicking on the factory.def file icon opens the DQW program
with these initial settings.
Very occasionally, something could occur in the Windows operating system that can
corrupt the definition file. If the LSW program is opened with no eye tracker, calibrator or
on screen video display card in the tower PC chassis, and then the program is closed
again, the LSW software definition file will save information indicating no cards are
present. In this case, open the factory.def file after the cards have been replaced in the PC.
In a more extreme case, if both definition files have been corrupted, the factory settings for
each of the 16 ISCAN system configuration screens are presented in Figure 12.5 below.
Manually enter the parameters shown in each of the configuration screens to restore the
system to its original settings. The system configuration panel can be opened by going to
the View menu and selecting System Configuration or by clicking on the "fork and spoon"
icon to the right of the File menu in the DQW software window.
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Section 12: FACTORY.DEF Settings
114
Figure 12.5: Factory.def ETL-600 Settings
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Section 12: FACTORY.DEF Settings
115
Figure 12.5: Factory.def ETL-600 Settings (cont’d.)
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Section 12: FACTORY.DEF Settings
116
Figure 12.5: Factory.def ETL-600 Settings (cont’d.)
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Section 13: IR Irradiance 117
Section 13: IR Irradiance and Safety
OSHA’s standard for safe levels of near-infrared radiation on the lens is 10 mW/cm2. The
IR LED illuminator has a total radiant output of 1.2 mW. The peak of this output is at 940
nm, and the half-power points are approximately 60 nm above and below this value. Even
if the entire output of the illuminator falls on the lens of the eye, the radiant flux striking
the lens or the retina cannot and does not exceed 1.2 mW/cm2 (0.29 mcal/sec/cm2). This
value is only 12% of the OSHA maximum radiation standard.
As to thermal levels, according to OSHA recommendations, white light of less than 1
cd/cm2 may be regarded of safe. A retinal exposure of 1.2 mW/cm2 of 940-nm light is the
equivalent of 0.06 cd/cm2 of white light. Therefore the IR LED illuminator exposes the
retina to only 6% of the OSHA maximum standard for thermal safety standard.
ISCAN thus certifies that the radiation and thermal levels of the IR LED illuminators
used in the Eye Tracking Laboratories fall well within OSHA recommendations.
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Section 14: Appendices 119
Section 14: ETL-600 Appendices
Appendix A: Single Plane/Computer Screen Stimulus Operation
The ETL-600 may be configured to monitor the combined eye/head gaze point of the
subject while using a single-plane computer monitor as the stimulus source.
Figure A.1 shows the basic component configuration for this type of application. Note that
this set-up uses a VGA-to-NTSC converter that is installed between the stimulus display
computer chassis and the VGA stimulus monitor. The ETL-600 will be configured to
display an indicator to the system operator where on the stimulus computer screen the
subject should fixate for each of the eye angle calibration points, and the laser pointer
calibration procedure is not required.
Figure A.1: ETL-600 Single Plane Configuration-
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Section 14: Appendices 120
Part A: Setting up the Single Plane/Computer Monitor Connections
1. First connect the VGA output of the stimulus computer to the VGA In port on the
iMicro Gold converter, using the short black VGA cable provided.
2. Connect the VGA Output cable of the stimulus monitor to the VGA Output
connector on the iMicro Gold converter unit. Plug in the +12VDC power connector
into the iMicro Gold. Plug in the +12VDC power supply to a120 VAC or 230 VAC
wall power source. When powered up, the green indicator light on the converter
unit will be visible.
3. Connect the video output of the converter unit to the VDU2 Scene Video In on the
back of the ISCAN PC chassis, using the phono cable. Note that there is a phono-
to-BNC adapter installed on the cable end connected to the VDU2 Scene Video In
end. See Figure A.2
Figure A.2: ETL-600 Computer Hook-up-
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Section 14: Appendices 121
Part B: Changing the Title of the Monitor to VDU monitor
When running the ETL-600 in this configuration mode, the operator may also want to
change the monitor displaying the VDU output to read “VDU Monitor” instead of “Global
View Monitor.” To change the text above the monitor, disable Track Active, and click on
the “Fork & Spoon” icon in the main LSW software window. When the ISCAN system
configuration panel comes up, select the OS Video Configuration and use the computer
keyboard to change the text in Chan 3 to read “VDU Monitor” as shown in Figure A.3
below.
Figure A.3: Changing the Name of the Monitor
Click on OK, and the LSW window will show the right hand monitor as “VDU Monitor.”
The VDU monitor displays the NTSC or television-format representation of the VGA
stimulus computer screen that is in front of the subject.
Part C: Entering the Planar Surface Coordinates
Using the ISCAN Environment Planes Layout panel as described in Section 7, enter the
planar surface coordinates for Plane 1, the stimulus computer monitor viewed by the
subject. Once the plane coordinates have been measured with respect to the magnetic
head tracker source and entered into the Planes Layout Editor, an alignment procedure is
required to match up the edges of the computer display as shown on the VDU monitor
with the coordinates entered into the Planes Layout Editor, specifying the plane.
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Part D: Alignment of the VDU Display Borders
Click on the Options button to bring up the video display unit controls panel as shown in
Figure A.4.
Figure A.4: VDU Controls Panel
Click the Single Plane mode button in the controls panel, and set the Plane # for 1. Click
the Up arrow for the Active Item box, until “Left Border” appears in the box, as shown in
Figure A.5.
Figure A.5: Selecting Left Border for Alignment
The left border in the VDU gray pseudo-screen will appear as a red line. Click and drag
the red border until the indicator in the VDU monitor display is exactly positioned at the
left side of the computer screen display on the VDU monitor. Refer again to Figure A.5.
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Section 14: Appendices 123
Once the indicator is lined up with the left border on the VDU monitor, click the Up arrow
roller again for the Active Item box. The right border marker will appear (as a red line), as
shown in Figure A.6.
Figure A.6: Selecting Right, Top, & Bottom Borders for Alignment
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Section 14: Appendices 124
Use the mouse to click and drag the red right border in the gray pseudo-screen until it is
properly assigned with the right edge of the stimulus computer screen display as shown in
the VDU monitor display.
Repeat the above procedures for the top and bottom borders as shown in Figure A.6.
The alignment procedure described above “matches up” the measured plane coordinates
with the edges of the stimulus computer screen display, so the head and eye line-of-sight
intersection with the planar surface will be accurately represented on the VDU monitor
display.
Part E: Verification of the Head Intersection
This procedure is the same as that described in Section 7, Part C.
Part F: Eye Angle Calibration
This procedure is similar to that described in Section 7, Part D, with the only difference
being that instead of using the laser pointer to indicate the position of the calibration
points to the subject, the operator simply positions the stimulus computer mouse at each
of the 5 calibration points. The position of the stimulus computer mouse is clearly visible
to the operator on the VDU monitor showing the stimulus computer’s display, and the
operator can easily move the mouse to be superimposed with the indicated calibration
symbol appearing on the VDU Monitor display. Upon completion of the eye angle
calibration as in Section 7, Part D, the position of the VDU monitor’s symbol will represent
the real-time intersection of the head and eye line-of-sight vector with the planar surface
of the computer monitor.
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Section 14: Appendices 125
Appendix B: Additional ISCAN Head-mounted Units
Like all ISCAN labs, the ETL-600 may be configured in a variety of ways to best suit the
research protocols for a given project. The headgear may need to fit in a more expansive or
in a more confined setting, to be steady with more or less physical activity, to fit adults or
children, to track the left or the right eye, etc.
Here is an example of a head-mounted configuration using a lightweight headband,
slightly different from that shown in Figure 3.6.
Figure B.1: Headband-mounted Monocular System
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Appendix C: Serial I/O
Auxiliary Serial Output Formats
ISCAN Serial Output Format (ASCII)
When the ASCII format is specified, the serial output data packet consists of a single line
of ASCII character bytes terminated by /r/n bytes (carriage return/line feed characters).
Each data byte is 8 bits with 1 start bit, 1 stop bit and no parity. Data is streamed out
with no active handshaking. Each data value is separated by a /t (tab) character. Each
data value will appear in the format XXXX.X, where each X represents the ASCII
representation of numerals 0 -> 9. This data format can be read by any terminal
emulation program (e.g. "Hyperterminal").
Standard Point-of-Regard output will consist of one data packet for each sample at 60
samples per second. Each packet will consist of two (2) data values POR_H and POR_V
that are the horizontal and vertical coordinates of the eye point-of-regard. Each of the
POR data values varies from 0 to 511 with (0,0) being the upper left corner of the viewed
scene.
When the ASCII format is specified, the serial output data packet consists of a single line
of ASCII character bytes terminated by /r/n bytes (carriage return/line feed characters).
Each data byte is 8 bits with 1 start bit, 1 stop bit and no parity. Each data value is
separated by a /t (tab) character. Each data value will appear in the format XXXX.X,
where each X represents the ASCII representation of numerals 0 -> 9. This data format
can be read by any terminal emulation program (e.g. "Hyperterminal") but the number of
data bytes transmitted will be significantly greater than when using the binary format
(see below).
Binary Output Format
When the binary format is selected, the serial output data packet consists of a set of data
bytes in a specific packet format. Each data byte is 8 bits with 1 start bit, 1 stop bit and no
parity. Each data value is multiplied by 10 and encoded as 2 integer bytes (LSB/MSB) in
the packet. The packet format is shown below:
Byte Value (Hex)
0 0X 44 - Header Byte 1
1 0X 44 - Header Byte 2
2 0X ?? - Ch1 Parameter x 10 (LSB)
3 0X ?? - Ch1 Parameter x 10 (MSB)
4 0X ?? - Ch2 Parameter x 10 (LSB)
5 0X ?? - Ch2 Parameter x 10 (MSB)
.
. (Repeated for each parameter)
.
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Remote Serial Controls
The DQW software also allows the user to remotely control data recording and send
synchronizing bytes to be incorporated in recorded data files.
To enable the serial input capability in DQW [see also Section 7((E)]:
• In the DQW "System Configuration" dialog, select the "Serial I/O" tab.
• Of the available COM channels, specify the COM port to be used as "Data I/O", the
baud rate to match the remote data sending system, and select "Input" as active.
• Click on "OK" to register changes to the system configuration.
• With the above steps completed, the DQW system is ready to receive serial commands
from a remote source. All DQW remote serial commands are single bytes between 128
and 255 (80 -> FF Hex).
• Whenever "Track Active" is enabled, the DQW system can receive and record any
single serial byte between 0 and 127 (00 and 7F Hex) as a synchronizing data marker.
These bytes are represented as parameter "SerIn0" wherever parameter selections are
made for display or recording in the DQW program.
• To trigger data recording via the serial port, in the DQW "System Configuration"
dialog, select the “Recording” tab and set the recording “Trigger” to “Serial.”
Remote Serial Command Bytes
Description of Data Recording Command Byte (Hex)
Start Recording 84 = 132 decimal
Quit Recording 88 = 136 decimal