Abstract
Contours provide an essential source of information about shape, and along contours points with the greatest magnitude of curvature tend to be most informative. This distribution of information is closely tied to internal generative models of contours employed by the visual system. In going from open to closed contours, the sign of curvature becomes perceptually significant, with negative-curvature sections of a contour being more informative, and playing an important role in part segmentation. The visual system represents complex shapes by segmenting them into simpler parts. Points of negative minima of curvature provide an important cue for part segmentation, but cannot fully predict it. A region-based representation of shape based on Bayesian estimation of the shape skeleton provides a successful account of part segmentation. As far as the visual representation of shape is concerned, contour geometry cannot ultimately be studied in isolation, but must be considered conjointly with region-based geometry.