Hierarchical Representation of Three-Dimensional Objects.

This report summarizes research on methods for representing within a computer the shapes of common objects that a robot or intelligent computer would have to deal with. Such a representation should be capable of supporting man-machine communication based on words and on pictures. It should also provide a basis for direct interaction of a machine with its environment, using sensors such as television or a range finder. As a vehicle for exploring these kinds of interaction we used a hierarchical, polyhedral representation to model electromechanical machinery. One feature of the method used was that the spatial relationships of one part to another could be characterized by attachment points located on each object. Symbolic descriptions were translated into geometric descriptions in terms of planes, edges, and points, from which visible outlines and occlusion relationships could be derived.