Abstract: This paper discusses the algorithm and implementation of the advanced surface design functions in BSURF-GI (an interactive 3D surface modelling system), presents a method which can do surface trimming along with the suface / surface intersection curves and filleting surface boundaries, and also points out the system further research direction and the way of integration with solid modelling system. In order to enhance the reliability of Newton-Raphson iteration method in surface / surface intersection, a new method, which can automatically find the effective initial iteration value for Newon-Raphson iteration, is also proposed, Finally some examples of advanced surface design functions are given.

Key words: surface intersecting, surface filleting, surface trimming, surface extending, surface blending