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

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.)