EFFECTS OF DIFFERENT TEXTURE CUES ON CURVED SURFACES VIEWED STEREOSCOPICALLY

Stereoscopic shape judgements can be modified by the addition of textu re cues. This paper examines the properties of texture that are respon sible for this effect. When a three-dimensional curved surface is proj ected onto a two-dimensional image, changes in surface orientation res ult in gradients of texture element size (or area), shape (compression ) and density in the image. Manipulating each of these gradients indep endently we found that 97% of the variance in the results could be acc ounted for by the compression gradient. When the texture pattern corre sponds to a highly anisotropic texture on the object's surface, shape- from-texture becomes ineffective. These results suggest that human sha pe-from-texture proceeds under the assumption that textures are statis tically isotropic, and not that they are homogeneous.