regis kopper mara g. silva ryan p. mcmahan doug a. bowman
TRANSCRIPT
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