SYSTEM AND METHOD FOR GENERATING SMOOTH LOW DEGREE POLYNOMIAL SPLINE SURFACES OVER IRREGULAR MESHES

A system and method for modeling smooth free-form shapes using B-splines over irregular meshes, in a simple and efficient manner, to generate a display of aesthetically pleasing shapes is disclosed. A low degree parametric polynomial representation is generated. As a result, techniques for surface-surface or ray-surface intersection are faster and more robust than possible with existing techniques. In accordance with the present invention, an input mesh M.sup.0 is initially simplified by isolating irregularities and constraining geometry. First, the input mesh M.sup.0 is subjected to general refinement, whereby a new mesh M.sup.1 is constructed, which in turn is subjected to constrained refinement, whereby another new mesh M.sup.2 is constructed. After the general and constrained refinement steps, the mesh M.sup.2 is broken up into a set of "quad-nets" corresponding to each of its vertices. Finally, these quad nets are used as local geometry, over which, 4 cubic Bezier triangles are constructed.