Effects of stereo viewing conditions on distance perception in virtual environments

technical reportSeveral studies from different research groups investigating perception of absolute, egocentric distances in virtual environments have reported a compression of the intended size of the virtual space. One potential explanation for the compression is that inaccuracies and cue confliicts involving stereo viewing conditions in head-mounted displays result in an inaccurate absolute scaling of the virtual world. We manipulate stereo viewing conditions in a head-mounted display and show the effects of using both measured and fixed interpupilary distances, as well as bi-ocular and monocular viewing of graphics, on absolute distance judgments. Our results indicate that the limitations on the presentation of stereo imagery that are inherent in head-mounted displays are likely not the source of distance compression reported in previous virtual environment studies

A Geometric Comparison of Algorithms for Fusion Control in Stereoscopic HTDs

This paper concerns stereoscopic virtual reality displays in which the head is tracked and the display is stationary, attached to a desk, tabletop or wall. These are called stereoscopic HTDs (Head-Tracked Display). Stereoscopic displays render two perspective views of a scene, each of which is seen by one eye of the user. Ideally the user's natural visual system combines the stereo image pair into a single, 3D perceived image. Unfortunately users often have difficulty fusing the stereo image pair. Researchers use a number of software techniques to reduce fusion problems. This paper geometrically examines and compares a number of these techniques and reaches the following conclusions. In interactive stereoscopic applications, the combination of view placement, scale and either false eye separation or ?-false eye separation can provide fusion control geometrically similar to image shifting and image scaling. However, in stereo HTDs image shifting and image scaling also generate additional geometric artifacts not generated by the other methods. We anecdotally link some of these artifacts to exceeding perceptual limitations of human vision. While formal perceptual studies are still needed, geometric analysis suggests that image shifting and image scaling may be less appropriate for interactive, stereo HTDs than the other methods