Summary for week 6

The Importance of Stereo and Eye-Coupled Perspective for Eye-Hand Coordination in Fish Tank VR

In order to interact with something, one needs to estimate distances accurately. Therefore, this paper studies the importance of coupling perspective to the user’s eye position versus stereoscopic viewing.

Usually, research into depth perception focuses on stereoscopic depth, motto parallax, occlusion or perspective. But depending on tasks, some cues are more useful than other ones. Concerning perspective distortion, little movements from the center of perspective produces important distortions, this is why the head position has to be tracked. However, this distortion is seldom noticeable by a human (what is called the robustness of linear perspective). For stereoscopic depth estimation, it can be recalibrated with touching. Indeed, former experiments showed that the time to perform a task is shorter when subjects are able to touch objects.

The method used here is Fish Tank VR, which creates a small-high quality virtual environment, eating to an acceptable accuracy for stereoscopic depth allowing to compute motion parallax. The experiment is closed to Fitt’s Law one, subjects had to tap on cylinder with a difficulty depending on the diameter of the cylinders and the distances between them.

A virtual environment has been set for both view and touching, while the hardware is made of a horizontal mirror, a monitor at 45° and a head device to track position. Shutter glasses with tracking of their position and orientation are also used to represent what each eye sees. The different conditions are whether same images are used for both eyes or not, whether the center of perspective is computed from the position of the eyes or is a default one (except for the virtual barrier) and the difficulty on diameters and distances which goes from 2 to 5 for each one.

Results are a variance for each parameter. They showed that advantages of stereo and head tracking are more importance for a greater difficulty. However, no improvement has been observed with coupling perspective. Thus, depending on the tasks performed, the cue leading to the greatest enhancement and its importance change. Also, an accurate coregistration of eye-and-hand coordinate space do not matter much.

As the understanding of visual perception grows over the years, could these results be used to help visually impaired?

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