Processes at discontinuities
Patrick J. Hayes, Michael Leyton · International Joint Conference on Artificial Intelligence · 1989
Leyton [1988] developed a set of rules by which process-history can be recovered from smooth natural shapes such as outlines of tumors, clouds, or islands. In this paper, we extend this analysis to deal with shapes with first-order discontinuities such as corners, creases and cusps. A simple extension to the notation allows one extra rule to cover most of these phenomena.