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Interactive Multi-Touch Powerpoint prsentation
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SURFACE COMPUTING&
MULTI-TOUCH DISPLAY DEVICES
Introduction
Surface computing is the term for the use of a specialized computer GUI in which traditional GUI elements are replaced by intuitive, everyday objects. Instead of a keyboard and mouse, the user interacts directly with a touch-sensitive screen.
Surface Computing Advertisement
Description
The multi-touch device is a user interface device that will allow a user to interact with a computer through use of a multi-touch display. Thus, it is a substitute to the keyboard and mouse. In this user can directly interact with the system with their fingers and not only this but with multiple touches at the same instant.
A basic touch-screen has three main
components: 1. Touch sensor; 2. Controller; 3. Software driver. The touch-screen is an input device, so it
needs to be combined with a display and a PC or other device to make a complete touch input system.
How Does a Touchscreen Work?
Touchscreen Technologies
Resistive Capacitive
Surface Projected
Optical imaging FTIR DI DSI
Resistive Touchscreen
Composed of multiple layers separated by thin spaces Using indium tin oxide (ITO) layers Different standards
4, 5, and 8 wire types Each have advantages
Resistive Touchscreen
User Presses Down Contact is Made Uniform Voltage on
First Screen for X Same on Second
screen for Y Happens
instantaneously
4-Wire design One screen for X
Another screen for Y
Both create voltage gradient.
Uses voltage divider
Advantages & Disadvantages
Works well with fingertip or stylus input
Generally most affordable touchscreen technology
Rugged/Durable Has multi-touch
input capabilities
Not as accurate
Multi-touch much more complex
Usually no discretion between stylus and hand
More pressure needed
Capacitive Touch Technology
Consists of: Insulator (glass or
Air) Conductive coating
(ITO) Two types:
Surface projected
Surface Capacitance
Only one side is coated
Electrodes at the edges Distribute voltage
Capacitor forms Current flows
Determine location Controller Ratio of currents
, XY coordinates
ITOGlass surface Finger
i
iv
AR
1i
R
Surface Capacitance
Projected Capacitance
Two parallel ITO(Indium Tin Oxide ) layers Two sheets of glass
Projected Capacitance E Field is projected
through glass Finger couples with E
field Capacitance changes
ITO
Air
ITO
ITO
Glass Surface
Finger
C1
Ct
Cnew=(C1*Ct) / (C1+Ct)
ITO
Air
ITO
C1 C2 C∞
Ceq C1+C2+……+C∞
DC
Capacitor at each point on the surface
Surface vs. Projected Limited resolution Single touch Operation with direct
contact
High resolution Multi touch Operation with
indirect contact
Multi-Touch Using Infrared
Frustrated Total Internal ReflectionFrustrated Total Internal Reflection
A process by which light is trapped within a medium and can be interrupted by a third medium of higher reflective index to cause light to escape.
Diffused Illumination
Diffused Surface Illumination
Alternative Single-Unit Design
Eliminates rear projectionExpensive Robustness
Software
Surface Capture via Detector Digitized View
Software Cont.
Interpret and Relay Information Assign Objects or gestures with Unique ID# and
location Compare and Execute
DigitizedObject
Application
ProtocolRaw Data Feedback to User
Universal Design Principles
Utility for all users Simple and intuitive
Touchscreens depend on visual feedback in order to use
Improving Accessibility?
Cursor movements
as command shortcuts
Takes place of keyboard shortcuts
Useful in applications where keyboard use is less prominent or undesirable
Pointing Device Gestures
Above: Some possible cursor movement patterns for use in gesture support.
Implementation: Step 1
Filter Input Sampling rate Smooth out input data, get rid of unnecessary
“noise” Simplify data analysis
Implementation: Step 2
Vectorize Separate x- and y-component Compute dominant component and ignore
smaller one Store in array
Implementation: Step 3
Matching Match captured vector array to pre-defined
gesture library If no match, pop smallest vector from array and
repeat matching process
Example
Fig. 1 – User input
Fig. 2 – Captured/filtered pointer data
Fig. 3 – After vectorization
Fig. 4 – Final matching result
Allows for a quicker and more efficient UI Universal Design
Enhances usability for visually-impaired as well as non-impaired
Easily added to existing touchscreen devices, no additional hardware required
Goal
A personal computer with 20 GB free
hard disk space, 1GB RAM and PIV + processor can be efficient enough.
The Windows Vista operating system was chosen because the CCV package is highly supported in Windows.
Computer Subsystem
Many different platforms can be
used to develop multi-touch applications utilizing TUIO events. Such platforms include:
Adobe Flash Java C++ Python
Application Development
Personal Computing Graphics Audio Mixing Video Playing Computer Gaming Slide Presentations
……and many more!
APPLICATIONS