Veridicality of three-dimensional shape perception predicted from amplitude spectra of natural textures.

We show that the amplitude spectrum of a texture pattern, regardless of its phase spectrum, can be used to predict whether the pattern will convey the veridical three-dimensional (3-D) shape of the surface on which it lies. Patterns from the Brodatz collection of natural textures were overlaid on a flat surface that was then corrugated in depth and projected in perspective. Perceived ordinal shapes, reconstructed from a series of local relative depth judgments, showed that only about a third of the patterns conveyed veridical shape. The phase structure of each pattern was then randomized. Simulated concavities and convexities were presented for both the Brodatz and the phase-randomized patterns in a global shape identification task. The concordance between the shapes perceived from the Brodatz patterns and their phase-randomized versions was 80-88%, showing that the capacity for a pattern to correctly convey concavities and convexities is independent of phase information and that the amplitude spectrum contains all the information required to determine whether a pattern will convey veridical 3-D shape. A measure of the discrete oriented energy centered on the axis of maximum curvature was successful in identifying textures that convey veridical shape.

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