Direct Blind Walking in a Different Virtual World

INTRODUCTION AND BACKGROUND

Betty J. Mohler†, Heinrich H. Bülthoff†, William B. Thompson* & Sarah H. Creem-Regehr+

†Max Planck Institute for Biological Cybernetics, Germany, http://www.kyb.mpg.de/~mohler

*University of Utah, School of Computing, +University of Utah, Psychology Department

A Full-Body Avatar Improves Egocentric Distance Judgments in an Immersive Virtual Environment

RESULTS

REFERENCES

Acknowledgements: This work was supported in part by NSF grant IIS-0745131.Special thanks to Michael Weyel and Martin Breidt for technical assistance, Naima Laharnar and Ekaterina Volkova for help with data collection, and Jenny Campos , Victoria Interrante, and William Warren for interesting discussions.

Distance judgments are compressed in head-mounted display (HMD)-based virtual environments (e.g., [Loomis and Knapp 2003]).

A user’s own body is almost never rendered in HMD-based VEs.

In the real world, a view of one’s body is not necessary in order to make accurate egocentric distance judgments [Creem-Regehr et al. 2005].

The visibility of a user’s body may affect the perceptual fidelity of virtual environments in the following ways:

Visual and/or proprioceptive feedback associated with an awareness of one’s body could provide a metric for scaling of absolute dimensions of space.

Presence of the body in the VE could serve to ground or situate the user in the VE, acting as a frame of reference.

Draper [1995] demonstrated that rendering parts of a user’s body in an HMD affects space perception, with equivocal results.

Beyond this work, the influence of the body on space perception within the context of virtual environments has been largely unexplored.

Experimental hypothesis:The lack of a fully-articulated self-avatar may contribute to the perceptual distortions in HMD-based VEs.

LOOMIS, J. M., AND KNAPP, J. 2003. Visual perception of egocentric distance in real and virtual environments. In Virtual and Adaptive Environments, L. J. Hettinger and M. W. Haas, Eds. Erlbaum, Mahwah, NJ, ch. 2, 21–46.CREEM-REGEHR, S. H., WILLEMSEN, P., GOOCH, A. A., AND THOMPSON, W. B. 2005. The influence of restricted viewing conditions on egocentric distance perception: Implications for real and virtual environments. Perception 34, 2, 191–204.DRAPER, M. 1995. Exploring the Influence of a Virtual Body on Spatial Awareness. Master’s thesis, Seattle, WA 98195, USA.

DISCUSSION

PART I: EXPLORATION PHASE

Independent t-test confirmed a significant difference between the percent distance walked in the two conditions (t= 4.261, p<0.01)

If participants are able to explore a fully-articulated avatar of themselves within the immersive VE they will make less errors in their subsequent egocentric distance judgments.

Future research will explore the impact of non-articulated avatars and non-co-located avatars on egocentric distance judgments in a virtual environment.

Pre-exploration without self-avatar (76.9%) results in more compression in egocentric distance judgments in a HMD-based VE as compared to pre-exploration with a full body self-avatar (89.3%)

EXPERIMENTAL METHOD

ResourcesTracking space with 12 Vicon Cameras (6x7 meters in size, 26-60 ms latency)eMagin HMD (40 degree diagonal FOV)Procedure:Experiment was a between-subject designIndependent Variable: Exploration condition, with or without a fully-articulated self-avatarDependent Variable: Egocentric distance judgment: direct blind-walking12 paid volunteers (6 for each condition)

Without Avatar

With Fully-Articulated Avatar

Participants could see their legs, arms, feet and hands freely moving in the space, these motions were consistent with their actual movement captured with Vicon. Each body segment of the avatar was scaled to match the dimensions of each participant. No line was placed on the floor in this condition.

For both conditions participants wore an eMagin HMD and a tight suit with 37 markers tracking their body movements in real-time.

Participants were in one of 2 five minute exploration conditionsFor both exploration conditions, participants were instructed to look down and explore the space where their body was located.

PART II: EXPERIMENTAL MEASURE

Direct blind-walking task in a different virtual world than was used for the exploration phaseWithout the view of the avatar