The basic concept for the data structure of solid modeling which is used in today’s practical CAD systems was first proposed in 1974 by B. G. Baumgart . This is known as the winged edge data structure (Fig. 18.1). This data structure deals with polyhedra consisting of only simply-connected faces, whose fronts and backs are distinguished, and explicitly describes the relations between an edge, and its incident vertices, edges and faces. The use of this data structure together with the Euler operators for creating solids (which will be discussed shortly) ensures that no solids will be produced with unrealistic topologies such as the Klein bottle. Moreover, the winged edge data structure expresses in a manner suited to computer processing, the property that solids have, that is, that its shape elements are continuously connected; this leads to efficient solid modeling.
KeywordsDual Operator Shape Element Rectangular Parallelepiped Inverse Operation Euler Formula
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