Increasing the precision of distant pointing for large high-resolution displays

1. Increasing the precision of distant pointing for large high-resolution displays Regis Kopper Mara G. Silva Ryan P. McMahan Doug A. Bowman

2. 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

3. 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…

4. 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)

5. Ray-casting • Precision issues • Natural hand tremor • Heisenberg effect • Mapping varies with distance • No Parkability • No supporting surface

6. 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

7. High-precision DistantPointing Techniques • Absolute and Relative Mapping (ARM) Ray-casting • Bimanual technique • Dominant hand controls cursor • Non-dominant hand controls mapping mode

8. 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

9. 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

10. 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

11. High-precision DistantPointing Techniques • Video

12. 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

13. Experiment • Experimental design • Atomic tasks • Selection and placement subtasks • Independent variables • Icon radius (selection) • Effective target size (placement) • Amplitude • Distance to display • Technique

14. 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

15. 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

16. Apparatus • Gigapixel Display • Vicon tracking system • Wireless mice withmarkers

17. 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

18. 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)

19. Procedure • Complex selection task • Complex placement task

20. Results • Atomic tasks

21. 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

22. High-precision DistantPointing Techniques • Results • Complex tasks • Variance was too large to result in any statistically significant results

23. 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

24. 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

25. 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

26. 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