Offsetting 3D Contours on Parametric Surfaces

Offsetting 3D contours on parametric surfaces is used in various design and manufacturing purposes such as shrinking and expanding trimmed surfaces, tolerancing and NC machining. The approach presented in this paper is coordinate-reference independent and allows the iterative calculation of interference-free 3D offset contours. The main elements in this approach are the iterative offset of parametric segments, their trimming and connection, and the handling of loops. The preliminary offsetting is achieved in the Cartesian domain associated with the surface. The interferences are then handled in parametric space.

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