A Rule Based System For 3D Shape Recovery From A Single Perspective View

A rule based system for 3D shape recovery and orientation estimation from a single perspective view is described. The primary input to our system is a set of line segments extracted from images by a complex segmentation process. In practice, humans are able to interpret 3D shape and orientation from 2D images with very little a priori information. The heuristics behind shape constancy suggest that certain regularity assumptions play an important role. Fifteen rules have been developed for the rule base which can be extended to include additional rules. The current rules deal with parallel lines, perpendicular lines, and right corners in the object space that lead to the given image instance recorded by the camera. Forward chaining methodology is adopted. The implementation is written in the rule base language OPS5 in conjunction with Pascal on a VAX/VMS system. Two examples are presented, and the results are consistent with human perception.