In an aspect graph, viewpoints are grouped into maximally connected viewing regions or cells formed by equivalent viewpoints. Two viewpoints are equivalent if the associated aspects are the same and the two viewpoints are connected by a path of viewpoints along which the aspect does not change. Topological descriptions of the views are used to establish equivalence criteria. The resulting subdivision of the viewing space can be naturally represented with a graph (the aspect graph), in which nodes represent general views of the object and the links represent transitions (called visual events) between neighbouring views. From a general viewpoint, a small movement may be made in any direction without changing the resulting image topology. Visual events occur when passing from one general viewpoint, through an accidental viewpoint, or singularity, to another general viewpoint.

Representing the visibility space

Computing exact aspect graphs

Polyhedral objects

Solids of revolution

Piecewise smooth objects

Summary: the applicability of aspect graphs

Contents: Viewer-centred representations

Comments to: Sarah Price at ICBL.