The Adaptive Bisector Method: Separating Slant and Tilt in Estimating Shape from Texture

Existing techniques for obtaining shape from texture estimate tilt and slant via a single computational mechanism. These techniques do not take advantage of the fact that tilt is relatively easy to estimate, and slant can be estimated more easily once tilt is known. This paper introduces the adaptive bisector method, which allows tilt and slant to be calculated separately, and by different computational mechanisms. The method makes minimal assumptions regarding the isotropy of surface textures. Evidence from psychophysical studies suggests that human observers are able to provide accurate estimates of tilt[8], but are poor at estimating slant [4]. Whilst no psychophysical claims are made regarding the means by which tilt and slant are computed in this paper, it is claimed that a method which depends upon two different mechanisms provides a plausible functional model for how human observers obtain shape from texture. Results for real and synthetic perspective images of textured planar surfaces are presented.