INCREASING THE PRECISION OF DISTANT POINTING FOR LARGE HIGH-RESOLUTION DISPLAYS

Regis KopperMara G. Silva

Ryan P. McMahanDoug A. Bowman

Introduction Large high resolution displays are

becoming cheap and common New interaction styles are needed

Traditional mouse isn’t enough Enhanced mouse techniques

Enhance target size and activation area E.g. Bubble cursor

Mouse acceleration

Introduction New interaction styles are needed

Even with enhancements, mouse may not be enough Slow (clutching) Single user Affords to sit at a fixed position, rather than

walking Distant pointing as alternative

Laser pointer metaphor Affords to stand and physically move across the

display Absolute (rapid) target acquisition, no clutching But it still has problems…

Distant pointing One of the fundamental classes of 3D

Interaction Ray-casting as a common and simple

implementation User points with a virtual ray extending from

the input device For large displays, intersection of ray with

display determines cursor position Freedom to move around Rapid movements to any point in the display Lack of precision makes it impractical (small

targets)

Ray-casting Precision issues

Natural hand tremor

Heisenberg effect

Mapping varies with distance

No Parkability

No supporting surface

Ray-casting Basic Enhancements

Increased cursor size Visible to the user from greater distances

Low-pass filter Dynamic recursive filter to eliminate low

frequency tracking jitter and hand tremor Framing

Movement of virtual ray when click occurs is ignored and position at beginning of click is used

High-precision DistantPointing Techniques

Absolute and Relative Mapping (ARM) Ray-casting Bimanual technique

Dominant hand controls cursor Non-dominant hand controls mapping mode

High-precision DistantPointing Techniques

Absolute and Relative Mapping (ARM) Ray-casting Scale factor determines relative area mapped

from absolute pointing Offers increased precision In this study, S=0.1 was used

Most effective when relative mode is not overused Only needed when high precision is desired

Offers high-precision pointing, but does not improve visual perception

High-precision DistantPointing Techniques

Zoom for Enhanced Large Display Acuity (ZELDA) Bimanual technique

Dominant hand controls the cursor Non-dominant hand controls a zoom window

Main idea: Magnified view which not only improves precision, but enhances visual acuity

High-precision DistantPointing Techniques

Zoom for Enhanced Large Display Acuity (ZELDA) Zoom window

When moving, small rectangle indicates zoomable area

When frozen, area underneath its center is zoomed in by a zoom factor

Zoom factor controlled by a scroll wheel When pointing to the sides or up/down, zoom

window can be resized Many strategies possible

Selection Placement

High-precision DistantPointing Techniques

Video

Experiment Conducted to evaluate two aspects

Do ARM and ZELDA increase precision compared to basic ray-casting, when strategy does not play a role? Strategy controlled by application Atomic tasks

How do ARM and ZELDA afford strategies that improve performance in realistic tasks? Users freely used the techniques Complex tasks

Selection Placement

Experiment Experimental design

Atomic tasks Selection and placement subtasks Independent variables

Icon radius (selection) Effective target size (placement) Amplitude Distance to display Technique

Experiment Experimental design

Atomic tasks Dependent variables

Number of errors Time

3 (I) x 2 (A) x 2 (D) x 3 (T) within subjects design T varying between subjects for ZELDA and ARM

conditions 5 measures per subject per condition

Average used in the analysis

Experiment Experimental design

Complex tasks Independent variable: Technique

ARM Ray-casting and ZELDA, compared to basic Ray-casting

Selection and placement tasks Dependent variables

Time to complete the task Strategies used

Apparatus Gigapixel Display

Vicon tracking system

Wireless mice withmarkers

Procedure Atomic tasks

ZELDA: zoom window was placed over the icon or the target

ARM Ray-casting: threshold indicating the beginning of relative mode placed under the icon or target

Guided practice

Procedure Complex tasks

Desktop-like interaction metaphor Subjects performed either ZELDA or ARM and

basic ray-casting Guided tutorial

Learn basic ray-casting and technique Think different strategies

Two types of tasks Selection (easy, medium and difficult) Placement (easy, medium and difficult)

Procedure Complex selection task

Complex placement task

Results Atomic tasks

Results Atomic tasks

ARM and ZELDA contained significantly less errors than basic ray-casting

Findings provide evidence that both ZELDA and ARM are indeed more precise than basic ray-casting and are most helpful for the hardest tasks

Comparing ARM with ZELDA it was found that ARM was significantly more precise for the hardest placement tasks ARM scale factor of ARM was bigger than ZELDA

zoom factors

High-precision DistantPointing Techniques

Results Complex tasks

Variance was too large to result in any statistically significant results

Results Complex tasks

Video analysis of strategies Most subjects preferred to maintain a distance to

the display 11 out of 16 subjects walked less using ARM or

ZELDA than using basic raycasting The high-precision techniques improved

performance among all the walking strategies employed by the subjects

ZELDA resulted in a larger zoom window set up time, thus increasing overall performance time

Subjects used relative mode for almost all interactions using ARM Direct and simple to activate

Discussion In realistic tasks, using a good strategy is

as important as using a high-precision technique Basic raycasting may be enough for not very

precise tasks ARM raycasting provides little overhead,

and could be used in most tasks without hurting performance

Due to its complexity, users who performed better with ZELDA were the ones who minimized zoom window operations

Discussion ZELDA and ARM are complementary and

could be combined into a single technique Naïve way: Provide one more button in the

zoom window controlled Too complex

More intelligent ways should be sought For example, popping up a zoom window every

time relative mode is activated Overall, ZELDA and ARM allow users to be lazy

both in terms of pointing accuracy and physical navigation, while maintaining precision and efficiency; basic raycasting can be as precise in most cases, but require users to work harder

Conclusions and Future Work It’s feasible to have 3D interaction with 2D

data and it is possible to increase precision For future work, a combined technique

should be sought We believe that there are models of human

motor behavior that allow the prediction of performance according to different strategies Such models could offer guidelines for effective

distant pointing techniques for large high-resolution displays