25 How to See a Simple World: An Exegesis of Some Computer Programs for Scene Analysis

The junction categories and link planting rules of SEE lyzed. That, however, is not the main point; it is merely typical of the way in which the program developed by a process of finding counter-examples that both invalidated old rules and hinted at new ones (Winston, 1973). The need to add and modify rules almost continuously to handle exceptions suggests that there is a basic flaw in the design. The flaw seems to be that Guzman used locally computed picture predicates as evidence for global scene-based properties. To avoid this one must ask what do the lines in the picture depict?