The Effects of Head-Mounted Display Mechanics on Distance Judgments in Virtual Environments

1. The Effects of Head-Mounted Display Mechanics on Distance Judgments in Virtual Environments Cynthia S. Sahm, Sarah H Creem-Regehr, William B. Thompson and Peter Willemsen Department of Psychology and School of Computing University of Utah

2. Outline • Introduction • Throwing vs. Walking • The Problem • Method • Results • Conclusion

3. Introduction • Our distance perception in virtual immersive environments is compressed • This paper attempts to give some insight into why that is • The study in this paper deals with absolute egocentric distance judgments in action space

4. Throwing vs. Walking as Indicators of Distance Perception • Standard blind walking • Locomotion • Egocentric updating of environment with ones movement • Can this influence the response measure

5. Blind throwing • View a target on the ground • Attempt to throw a bean bag at target while blindfolded • Been shown to be accurate in real world conditions

6. Experiment • Subjects judge distances using both throwing and blind walking in a virtual and a real environment • Distances 3, 4, 5 and 6 meters

7. Result

8. Conclusion • Both methods show similar results in both a real and a virtual environment • This suggests that distance compression is not caused by the specific response measure

9. Problem • Distance judgments in virtually immersive environments are compressed. • The quality of the rendered graphics does not explain this, Thompson et al. • Limited field of view does not explain this, Knapp and Loomis • Does the mechanical aspects of wearing a HMD explain this phenomenon?

10. Problem cont. • How can a HMD affect distance judgments? • Mass • Weight • Distribution • Moment of inertia • Angle of declination

11. Method • Three viewing conditions • Virtual world using a HMD • Real world using a mock HMD • Real world condition • Tested both direct and triangular walking

12. Method cont. • 83 students (42 male, 41 female) • Each subject experienced one of six possible conditions • Triangulated walking 5m, 10m, 15m • Direct walking 4m, 6m, 8m • Each subject performed 15 trials (3 practice

13. Direct and Triangulated walking target target Direction to apparent target Distance To target Direction to target ≈70º ≈ 2.5m

14. Mock HMD • Replica shell of nVisor SX HMD • Mass of mock HMD was adjusted using small weights

15. Mock HMD • Location of center of mass • Point of balance when suspended from a string • Moments of inertia of the mock HMD • Period of oscillation when attached to a pendulum

16. Environments Real World Virtual World

17. Procedure • The authors did not address specific instructions given to the subjects. • Previous experiment instructions • Given written instructions • Given a demonstration of the task in space smaller than the actual experiment spatial layout • Allowed to practice blind walking prior to experiment • Instructed to get a good image • Allowed to rotate their head about their neck • Not allowed to move their head from side to side

18. Result, direct walking

19. Result, triangulated walking

20. Mock HMD vs High Quality CG High quality CG

21. Conclusion • Mechanical aspects of wearing a HMD does account for some of the distance compression experienced in virtual environments • HMD does not solely explain the compression

22. Questions?