next up previous contents
Next: Describing 2D Shape with Up: Two Methods for Qualitative Previous: A Two Dimensional Derivative

Qualitative Two Dimensional Shape Description

This section describes in detail the two systems for two dimensional shape representation which developed from the approaches to solid modelling discussed above. I have used both of these systems to construct descriptions of example shapes and scenes. Chapter 5 describes programs which operate on both representations, and discusses the relative advantages of each one.

For each of the two approaches, I will discuss the methods used to represent four aspects of qualitative shape: primitive shape, relative size, object-interior position (the relative position of subshapes within an object), and object-exterior position (The relative positions of complete objects, or of parts on different objects). These four are sufficient to describe any combination of objects in a scene, and any combination of subshapes within an object.


Alan Blackwell