Fish tank virtual reality

The defining characteristics of what we call “Fish Tank Virtual Reality” are a stereo image of a three dimensional (3D) scene viewed on a monitor using a perspective projection coupled to the head position of the observer. We discuss some of the relative merits of this mode of viewing as compared to head mounted stereo displays. In addition, we report the experimental investigation of the following variables: 1) whether or not the perspective view is coupled to the actual viewpoint of the observer, 2) whether stereopsis is employed. Experiment 1 involved the subjective comparison of pairs of viewing conditions and the results suggest that head coupling may be more important than stereo in yielding a strong impression of three dimensionality. Experiment 2 involved subjects tracing a path from a leaf of a 3D tree to the correct root (there were two trees intermeshed). The error rates ranged from 22% in the pictorial display, to 1.3% in the head coupled stereo display. The error rates for stereo alone and head coupling alone were 14.7% and 3.2% respectively. We conclude that head coupling is probably more important than stereo in 3D visualization and that head coupling and stereo combined provide an important enhancement to monitor based computer graphics.