Multi - Scale Vector - Ridge - Detection for Perceptual Organization Without Edges

We present a novel ridge detector that nds ridges on vector elds. It is designed to automatically nd the right scale of a ridge even in the presence of noise, multiple steps and narrow valleys. One of the key features of such ridge detector is that it has a zero response at discontinuities. The ridge detector can be applied both to scalar and vector quantities such as color. We also present a parallel perceptual organization scheme based on such ridge detector that works without edges; in addition to perceptual groups, the scheme computes potential focus of attention points at which to direct future processing. The relation to human perception and several theoretical ndings supporting the scheme are presented. We also show results of a Connection Machine implementation of the scheme for perceptual organization (without edges) using color. Acknowledgements: This report describes research done at the Arti cial Intelligence Laboratory of the Massachusetts Institute of Technology. Support for the Laboratory's Arti cial Intelligence Research is provided in part by the Advanced Research Projects Agency of the Department of Defense under Army contract DACA76{85{C{0010, and in part by ONR contracts N00014{85{K{0124 and N00014-91-J-4038.