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27 August 1992 Oblique effect in stereopsis?
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Proceedings Volume 1666, Human Vision, Visual Processing, and Digital Display III; (1992) https://doi.org/10.1117/12.135992
Event: SPIE/IS&T 1992 Symposium on Electronic Imaging: Science and Technology, 1992, San Jose, CA, United States
Abstract
Contrast thresholds are lower for detection of a vertical pattern than for an obliquely-oriented pattern. Is there an analogous oblique effect for the depth threshold of a stereoscopic luminance pattern? If so, why? Are the causes different from those for an oblique effect with monocular vision? To explore these issues, we used stereoscopic blurry bar (D6) luminance patterns with a peak spatial frequency of 2 or 4 cycles/degree (cpd) and either a vertical or an oblique orientation. We obtained psychometric functions for data obtained from a method of constant stimuli procedure, using 100 forced-choice trials for each datum. For each of three observers we estimated stereoacuity with a maximum-likelihood curve-fitting procedure. Subjects showed better stereoacuity for the vertical spatial patterns than for the oblique patterns. Some possible causes are that for oblique patterns (unlike vertical patterns) (1) the total vertical extent of the pattern is shrunk by a factor of sin((theta) ), where (theta) equals 90 degree(s) for vertical; (2) the pattern is 'stretched out' in the horizontal direction by a factor of csc((theta) ); (3) there are vertical as well as horizontal retinal disparities. Perhaps the resulting sparseness of horizontal disparity information or the potential vertical disparities in the oblique patterns reduce stereoacuity. To disentangle these causes, we used several different experimental conditions (e.g., elongation of oblique patterns) run in randomized blocks of trials. We will discuss these results and implications for stereopsis.
© (1992) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Elizabeth Thorpe Davis, Robert A. King, and Alana M. Anoskey "Oblique effect in stereopsis?", Proc. SPIE 1666, Human Vision, Visual Processing, and Digital Display III, (27 August 1992); https://doi.org/10.1117/12.135992
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