Form Feature Representation in a Structured Boundary Model

Abstract

A relational boundary model of a solid object, based on a structured graph representation is presented, and its application to the description of form features is discussed. In this hierarchical graph structure, called Structured Face Adjacency Graph, the global shape of an object is represented at the highest level of abstraction, while its representation details can be described at lower levels of specification. In the paper, we show how explicit topological form features, grouped into three main categories, namely through holes, protrusions or depressions, and connections, can be represented in this graph model as lower level attributes of the main object shape. We define also two basic transformations on the structured face adjacency graph, termed refinement and abstraction, which allow local modifications of its hierarchical structure, especially useful to reorganize object descriptions during the process planning step.