On Alternate Solid Representations and Their Uses*

We discuss a number of surface and solid representations especially suited to specific tasks arising in product design and analysis. The Brep-index is a data structure well-suited to support collision detection and analysis in mechanical simulation. The dimensionality paradigm provides a simple and effective mechanism for representing constrained surfaces pre-cisely. The skeleton, finally, is an informationally-complete solid represen-tation that shows promise for automated mesh generation, feature recog-nition and extraction, and for geometric tolerancing.