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Krista A Ehinger, Yiming Qian, Laurie M Wilcox, James H Elder; Influence of 2D Shape on Contour Depth Perception. Journal of Vision 2019;19(10):16b. doi: https://doi.org/10.1167/19.10.16b.
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© ARVO (1962-2015); The Authors (2016-present)
Objective. The bounding contour of an object serves as an important constraint in recovering 3D shape. In the image, the bounding contour is planar, but it projects from a 3D space curve lying on the object - the rim (Koenderink, 1984) - that may be oblique to the observer and non-planar. Determining the 3D shape of this space curve from a 2D projection is ill-posed, but statistical regularities of objects (smoothness, symmetry, and parallelism) and projection (the generic view assumption) may provide cues. Here we assess this hypothesis using a novel psychophysical approach.
Methods. From random perspective projections of 3D laser-scanned objects (Mehrani & Elder, 2017) we generated a set of 3D rims subtending an average of 8.3 dva and displayed them stereoscopically using a Wheat-stone stereoscope. To assess the effect of the shape of the 2D bounding contour on perceived depth, two modified configurations of the rim were generated. In the shifted configuration, the 2D shape matched the original bounding contour, but the depth values were rotated along the contour by one quarter of the contour length. In the circle configuration, the 2D shape was a circle with the same depth values as the original rim. Observers were shown a contour in of the three stimulus configurations for two seconds, followed by the same contour but in one of the other two configurations, and asked to adjust the depth gain of this second stimulus to match the depth range perceived in the first stimulus. Results. Results indicate that observers perceive greater depth in the shifted configuration than the other two configurations. These findings show that the 2D shape of a contour can influence the perceived variation in depth, suggesting a sensitivity to statistical regularities linking the 3D rim and its image projection.
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