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Proceedings of CAD'14, 2014, 11-13
Parts Localization Oriented Practical Method for Point Projection on Model Surfaces based on Subdivision
Jianhuang Wu, Shenzhen Institutes of Advanced Technology, China
Abstract. In algorithms of parts localization, the closest point of a measured point on model surface is chosen as its correspondence, which is also the key to process the localization of the measured data to CAD model. At present, Newton-type iterations are the most popular solving strategy. But, this process cannot provide full assurance that all solutions have been found. Ma and Hewitt have also showed that Newton-Raphson method occasionally still gives some wrong results even with a quite good initial value when applying it on the whole surface. Occasional errors maybe is trivial for the graphics processing, but it is fatal for some practical industrial applications. For example, in the machining allowance optimization, the distance between a point and its closest point on model surface is evaluated as the machining allowance, if wrong closest point is calculated at some area, an improper distribution of stock allowances, especially stock material shortage at this area, may appear such that the qualified blanks may be considered to be defective ones that need to be returned to the factory and is reworked, even although the CAD model actually can be enclosed within the blank. For such industrial applications, the robustness of calculation of the closest point may be found to be more important and economical than the savings of the computing time.
Keywords. Parts localization, point projection, model surface, subdivision