Computing the aspect graph for line drawings of polyhedral objects

J.J. Koenderink and A.J. van Doorn (1979) introduced aspect graphs as a way of representing 3-D shape for object recognition. The set of viewpoints on the Gaussian sphere is partitioned into regions such that in each region the qualitative structure of the line drawing remains the same. The viewing data of an object are the partition of the Gaussian sphere together with representative line drawings for each region of the partition. The authors present an algorithm for computing the viewing data of polyhedral objects. In the course of presenting the algorithm, they provide a full catalog of the visual events that occur for this type of object