Week 6 Summary: Stereo vs. Eye-coupled perspective

Before reading this paper, I googled Fish Tank VR and found the Colin Ware and Kevin Arthur paper title “Fish tank Virtual reality” and their abstract concluded 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. When I started reading this paper, I was surprised to find the exact opposite finding, that for their task stereo was considerably more important than eye-coupled perspective. So it was interesting to read how the importance of the two factors vary based on task.

The paper starts off discussing different depth perception techniques, mainly Stereopsis and Motion parallax. Stereoscopic depth is the information we gain from disparities—differences in relative separation between pairs of features imaged in the two eyes. Whereas, motion parallax refers to the depth information that is obtained as an observer moves relative to the environment. They provided results on the importance of each technique based on task, so a task in which a user is stationary (so motion parallax doesn’t have much play), stereoscopic depth plays a more important role and that’s what the researchers have focused on, in this study. An example given was of a simple observation that people who do fine positioning tasks, such as threading a needle, hold their heads steady and therefore do not appear to use parallax information.

They also realized touch may also be important in 3D visually guided reaching because touching an object may cause a recalibration of the stereoscopic depth estimation system. They found that enabling subjects to feel the surfaces they were tapping increased the rate at which they could perform the task by about 12%. The experiment implemented a variation of the Fitt’s Law experiment to test the impact of stereo vision vs head-tracked vision. Studying the index-of-performance benefits, it was identified that gain in performance from including both head tracking and stereo was more than 50% of this was attributed to stereo, whereas 11% was attributable to eyecoupled perspective.

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