Characterising polygons qualitatively

Abstract

So far, we have analysed arrangements between disconnected intervals. Intervals can be considered as abstractions of objects, representing their intrinsic orientation, their extension seen from a particular viewpoint, or their direction of movement. The length of an interval may represent the length of the object, its speed, or the distance between two objects or components of one object. However, in order to describe the shape of single objects we need to consider arrangements of connected lines. That is, we are interested in describing the outlines of shapes, which constrain how objects are related to other objects and their environment.