Breps as Displayable-Selectable Models in Interactive Design of Families of Geometric Objects

Ari Rappoport

In classical geometric modeling, the primary objects of interest are geometric pointsets, the primary representation scheme for which is the boundary representation (Brep). Modern geometric modeling focuses on parametric families of pointsets, defined using geometric operation graphs (GOGs), features and constraints. During interactive design of families of objects, users interact with an example object from the family. The example object is a pointset, hence is usually modeled using the Brep.

In this paper we study the issue of which modeling scheme is most appropriate for the example object. We identify two major operations which such a modeling scheme must support: display and selection. Selection can be further decomposed into picking, invariant naming, and persistent naming. We introduce the term Displayable-Selectable Models (DS-models) as a generic term for models providing display and selection functionality. We discuss the suitability of Breps to serve as DS-models and whether other, perhaps simpler, representations could also serve as DS-models.

Geometric Modeling: Theory and Practice, Strasser, Klein, Rau, (Eds), Springer-Verlag, 1997, pp. 206-225 (proceedings, Theory and Practice of Geometric Modeling (Blaubeuren II), Tübingen, Germany, October 1996.)