Conveying three-dimensional shape with texture

Studies have shown that although shading is an important shape cue, visual perception of surface shape from shading only is severely limited when the surface is viewed locally without other visual cues such as occluding contours [Mamassian and Kersten 1996; Erens et al. 1993], Research has shown that when the "right" texture is added to the surface, observers can reliably infer the 3D structure of the underlying shape. In our previous work we have found that the performance of subjects' shape judgment is significantly better when the shaded surface is textured with a principal direction oriented pattern than other directional texture following either a uniformly constant direction or varying non-geodesic paths unrelated to the surface geometry. In this paper we report our findings of a new study further investigating the effect of anisotropic textures on shape perception when the surface texture is represented in the form of a pattern of luminance variations as well as of surface relief variations. We hypothesized that 1) observers' performance would be better with relief textures than luminance textures, and that 2) it would be poorer with the anisotropic textures that do not follow the principal directions. The results confirmed both of our hypotheses.