5.1
Figure 5.1: Three nodes and their unary, binary and triple
relations in the RS representation.
From (Li 1992b) with permission; © 1992 Elsevier.
In high level image analysis, we are dealing with image features, such as critical points, lines and surface patches, which are more abstract than image pixels. Such features in a scene are not only attributed by (unary) properties about the features themselves but also related to each other by relations between them. In other words, an object or a scene is represented by features constrained by the properties and relations. It is the bilateral or higher order relations that convey the contextual constraints. They play a crucial role in visual pattern matching.