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- Models are a more explicit representation than CSG.
- The object is represented by a complicated data structure giving
information about each of the object's faces, edges and vertices and how they
are joined together.
- Appears to be a more natural representation for Vision since
surface information is readily available.
- The description of the object can be into two parts:
- -- records the connectivity
of the faces, edges and vertices by means of pointers in the data structure.
- -- describes the exact shape and position of each
of the edges, faces and vertices.
- The geometry of a vertex is just its position in
space as given by its (x,y,z) coordinates.
- Edges may be straight lines, circular arcs, etc..
- A face is represented by some
description of its surface (algebraic or parametric forms used).
Fig. 40 Faces, edges and vertices