TESSELLATING TRIMMED NURBS SURFACES

An algorithm for obtaining a piecewise planar approximation of a trimm ed NURBS surface is presented. Given a model space tolerance epsilon, the algorithm triangulates the parameter space domain of the trimmed s urface such that the 3D planar approximation, obtained by mapping 2D t riangles onto the surface, deviates from the trimmed surface by no mor e than epsilon. The number of triangles computed in parameter space de pends on the bounds of the second derivatives. A detailed discussion o f the algorithm and a practical error analysis of the tessellation are provided.