GVU Technical Report Number:
GIT-GVU-00-09
Title:
An Analytic Comparison of Alpha-False Eye Separation, Image Scaling and
Image Shifting in Stereoscopic Displays
Authors:
Zachary Wartell
Larry F. Hodges
William Ribarsky
Abstract:
Stereoscopic display is a fundamental part of many virtual reality systems.
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 pairs and the user perceives a single 3D
image. In practice, however, users can have difficulty fusing the stereo
image pairs into a single 3D image. Researchers have used a number of
software methods to reduce fusion problems. Some fusion algorithms act
directly on the 3D geometry while others act indirectly on the projected
2D images or the view parameters. Compared to the direct techniques,
the indirect techniques tend to alter the projected 2D images to a lesser
degree. However while the 3D image effects of the direct techniques are
algorithmically specified, the 3D effects of the indirect techniques require
further analysis. This is important because fusion techniques were
developed in non-head-tracked displays that have distortion properties not
found in the modern head-tracked variety. In non-head-tracked displays,
the non-head-tracked distortions can mask the stereoscopic image artifacts
induced by fusion techniques but in head-tracked displays distracting
effects of a fusion technique may become apparent. This paper is
concerned with stereoscopic displays in which the head is tracked and the
display is stationary, attached to a desk, tabletop or wall. This paper
rigorously and analytically compares the distortion artifacts of three
indirect fusion techniques, alpha-false eye separation, image scaling and
image shifting. We show that the latter two methods have additional
artifacts not found in alpha-false eye separation and we conclude that
alpha-false eye separation is the best indirect method for these displays.
Keywords:
Virtual reality, stereoscopic, head-tracking, distortion
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