INTEGRATION OF TWO GEOMETRIC MODELERS BASED ON POLYHEDRA AND RATIONAL PARAMETRIC BICUBICS.

Interactive computer aided design (CAD) of solid geometric models generally requires use of surface based boundary representation or primitive based constructive solid geometry. Practical boundary modeling CAD systems have been built which define solid models as polyhedral enclosures or regions bounded by rational parametric bicubics. These two surface forms offer somewhat complementary features: polyhedral models are amenable to Boolean operations and hidden surface removal calculations, but are inaccurate for defining curved surfaces; while rational bicubics based surface models are capable of representing arbitrary shapes, but do not lend themselves to simple algorithms when Boolean operations or hidden surface removal are required. This paper reports on an integrated approach which combines a polyhedral geometric modeler with a surface modeler based on rational parametric bicubics.