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Jeffrey A. Saunders, Benjamin T. Backus; Perception of slant-from-texture for textures with oriented symmetry. Journal of Vision 2005;5(8):996. doi: 10.1167/5.8.996.
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© ARVO (1962-2015); The Authors (2016-present)
When a surface with a regular texture is viewed in perspective, the projected texture is systematically distorted, providing information about its 3D structure. Regularities along different texture dimensions (eg size, shape, anisotropy) potentially provide separate 3D cues. Previous work has focused primarily on texture foreshortening, and gradients of texture size and spacing. When a texture has an oriented symmetry, another potential cue is perspective convergence: symmetry lines that are parallel along a surface project to lines that vary in orientation in an image (eg converging lines in a linear perspective picture). The experiments reported here test whether this regularity contributes to perception of slant from texture, particularly in the case of surfaces oriented near the frontal plane, when other texture cues provide weak information. Stimuli simulated slanted planar surfaces covered with uniform dots. In one condition, dots were positioned by a random isotropic process. In the other conditions, dots were positioned on a hex grid, oriented so that rows were either at 0 deg and ±60 deg relative to the tilt direction (aligned grid), or at ±30 deg and 90 deg (perpendicular grid). Subjects performed a forced-choice slant-nulling task. In experiment 1, textures were presented monocularly, and in experiment 2, textures were presented binocularly with stereo information conflicting by ±5deg. Discrimination thresholds from texture alone were higher for isotropic textures than for either hex grid texture, and were higher for the perpendicular grids than for the aligned grids. In the stereo conflict experiment, subjects gave greater weight to texture information in the aligned grid condition than in either of the other conditions. Both results support the conclusion that the visual system uses perspective convergence to perceive slant, and that symmetries aligned with the tilt direction are most effective for conveying slant from convergence.
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