Key characteristics of specular stereo
Muryy, Alexander A
Fleming, Roland W
Journal of Vision
Association for Research in Vision and Ophthalmology
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Muryy, A. A., Fleming, R. W., & Welchman, A. (2014). Key characteristics of specular stereo. Journal of Vision, 14 (14)https://doi.org/10.1167/14.14.14
Because specular reflection is view dependent, shiny surfaces behave radically differently from matte, textured surfaces when viewed with two eyes. As a result, specular reflections pose substantial problems for binocular stereopsis. Here we use a combination of computer graphics and geometrical analysis to characterize the key respects in which specular stereo differs from standard stereo, to identify how and why the human visual system fails to reconstruct depths correctly from specular reflections. We describe rendering of stereoscopic images of specular surfaces in which the disparity information can be varied parametrically, and independently of monocular appearance. Using the generated surfaces and images, we explain how stereo correspondence can be established with known and unknown surface geometry. We show that even with known geometry, stereo matching for specular surfaces is non-trivial because points in one eye may have zero, one or multiple matches in the other eye. Matching features typically yield skew (non-intersecting) rays, leading to substantial ortho-epipolar components to the disparities, which makes deriving depth values from matches non-trivial. We suggest that the human visual system may base its depth estimates solely on the epipolar components of disparities while treating the ortho-epipolar components as a measure of the underlying reliability of the disparity signals. Reconstructing virtual surfaces according to these principles reveals that they are piece-wise smooth with very large discontinuities close to inflection points on the physical surface. Together, these distinctive characteristics lead to cues that the visual system could use to diagnose specular reflections from binocular information.
Stereopsis, Matching, Correspondence Problem, Binocular Vision, Specularity, Material Perception
The work was funded by the Wellcome Trust (grants 08459/Z/07/Z & 095183/Z/10/Z) and the EU Marie Curie Initial Training Network “PRISM” (FP7-PEOPLE-2012-ITN, Agreement: 316746).
Wellcome Trust (095183/B/10/Z)
EC FP7 MC ITN (316746)
External DOI: https://doi.org/10.1167/14.14.14
This record's URL: https://www.repository.cam.ac.uk/handle/1810/246257