Week 6 Summary
The importance of Stereo and Eye Couple Perspective for Eye-Hand Coordination in Fish Tank VR
Stereoscopic depth information is gained from disparities whereas motion parallax information is obtained when the user moves relative to the environment. Previous studies have shown that stereoscopic viewing has a large advantage in visually guided tasks but head tracking has no significant advantages. This paper is based on the experiment conducted to determine if not only stereoscopic viewing but also head tracking is actually advantageous for such tasks by forcing the subjects to make substantial changes in viewing position.
This paper used a variation of the Fitts’ Law tapping task to determine the relative importance of stereo and head tracking for visually guided tasks. In their experiment, the subjects had to tap from the top of one cylinder to another. The diameter of the cylinder tops and distances between them were varied to generate different difficulty values. The experiment measured the inter-tap interval as the subjects tapped a whole set of targets in a series.
The experiment used Fish tank VR setup to create a small high quality virtual environment. The apparatus contained a mirror mounted horizontally with a monitor mounted above it at a 45 deg angle. The reason behind using the opaque mirror was to enable users to place their hands in the virtual workspace as this enabled them to study the eye-hand coordination. Studies show that haptics can improve the task performance by about 12% and so they used a Phantom device to track the position of the hand held stylus. The Phantom device could provide arbitrary force to the tip of that stylus. LCD shutter glasses were used for stereoscopic display with an attached sensor for head tracking.
Study was conducted with 19 subjects out of which 4 were lab members and others undergraduates. The results showed that average time for the task increased by 11% without head tracking and by 33% without stereo. Thus, the results showed that stereo is more important than eye coupled perspective for such tasks and the benefits increase with increase in difficulty and as the targets get smaller. However there was no evidence to conclude that head tracking would enable a more rapid adjustment after a change of head position.
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