DISCRIMINATION OF PLANAR SURFACE SLANT FROM TEXTURE - HUMAN AND IDEALOBSERVERS COMPARED

In order to quantify the ability of the human visual system to use tex ture information to perceive planar surface orientation, I measured su bjects' ability to discriminate planar surface slant tangle away from the fronto-parallel) for a variety of different types of textures and in a number of different viewing conditions. I measured the subjects' discrimination performance as a function of surface slant, field of vi ew size and surface texture structure. I compared the subjects' perfor mance with that of ideal observers derived for each of the available t exture cues-texel position, scaling and foreshortening. The results ca n be summarized by four points: (i) subjects' discrimination performan ce improves dramatically with increasing surface slant, tracking the p erformance of the ideal observers; (ii) subjects can integrate texture information over a large range of visual angles; (iii) comparisons be tween human subjects and ideal observers show that the human observers rely to some degree on foreshortening information; and (iv) similar c omparisons show that in using foreshortening information, subjects rel y to some extent on a prior assumption of isotropy. (C) 1998 Elsevier Science Ltd. All rights reserved.