A Graphical Approach to Approximate Offset Computation

Generation of the offset of a curve is an important operation in many CAD/CAM applications. In the generation of CNC toolpath for 2.5D machining, the toolpath is the offset of the part boundary. A major problem in the computation of the offset of a curve is the detection and the subsequent removal of self-intersecting loop. While many different techniques have been reported in the literature, in general they are complex and not efficient. In this paper, the problem is re-formulated as a graphical problem and solved using the graphics hardware. The generation of the offset, the detection and the removal of self-intersection are achieved through a rendering process. With the recent advent in the processing power of the GPU, this process is very efficient. This new technique can be used to compute offsets of planar curves and offsets of curves on free-form surfaces.