Modeling G² Continuous Free-Form Surfaces by C-C Subdivision Method and Manifold Method

By improving the algorithm to construct n-sided patches given by J. Cotrina et al, a n-sided patch is constructed with uniformly cubic B-spline boundary, whose control mesh is the mesh formed by 5-ring of an extraordinary point in C-C subdivision mesh. The patch can G² continuously joint with a C-C subdivision surface. On this basis, the question on how to form and fill n-sided holes in C-C subdivision surfaces is discussed. A method is given to solve the problem in modeling low-degree G² continuous free-form surfaces based on arbitrary topology meshes. The blend is realized between surfaces constructed by manifolds and C-C subdivision surfaces. Finally, several examples are presented.