Offsetting 3D contours on parametric surfaces

Offsetting 30 contours on parametric surfaces is used in various design and manufacturing purposes such as shrinking and expanding trimmed surfaces, t olerancing and NC machining. The approach presented in this paper is coordi nate-reference independent and allows the iterative calculation of interfer ence-free 30 offset contours. The main elements in this approach are the it erative offset of parametric segments, their trimming and connection, and t he handling of loops. The preliminary offsetting is achieved in the Cartesi an domain associated with the surface. The interferences are then handled i n parametric space.