A Geometric Comparison of Algorithms for Fusion Control in Stereoscopic HTDs

Abstract

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.