Surface Interpolation Method for Large Non-four-sided Areas including Some Concave Areas

Three-dimensional surface design of industrial products includes a wide variety of non-four-sided areas. Subdivision methods are widely used to interpolate the surface of these areas. But, smooth surface shape control of multiple surfaces is difficult. We used the trim surface for interpolation of these area, but shape control of the trim surface was also difficult. We have now developed a surface interpolation method for large non-four-sided areas that improves shape controllability by using NBG (NURBS Boundary Gregory) patch. This method classifies non-four-sided areas into five types of convex and concave shapes, and the interpolation manner is determined by shape type. It has been used to improve the surface modeling of industrical products.