| Smooth and fluent contour is the necessary quality of modern automobiles, and it is also the key factor for the automobile to survive and win in the intense market competition, so smoothing technologies of class A surfaces for auto-body are being put into a higher level. Although much research on curves and surfaces smoothing has been done by domestic and foreign scholars, systematic research on class A surfaces smoothing for auto-body has been seldom discussed. So it is difficult to satisfy the need of quick development of auto-body surfaces.Aiming at the above problems, research on the key smoothing techniques of class A surfaces are presented in this paper, which mainly includes:point cloud processing, curves, surfaces reconstruction, surfaces quality evaluation.Firstly, the processing techniques of point cloud are described. In accordance with graphic coordinate transform theory, the alignment method of point cloud data based on the points fit method is presented, which can achieve the accurate alignment of point data.Secondly, surfaces reconstruction technology is given. It is the vertices arrangement that influences the quality and efficiency of surfaces smoothing. So a principle for vertices arrangement of class A surfaces is proposed with the help of the practical experience. And then the theoretical curves are emphasized in transitional surface smoothing. An example is given, which verified that the method can improve the efficiency of smoothing surfaces greatly.Finally, smoothing processing and quality evaluating for class A surfaces are described. With the help of evaluation criteria of various specific evaluating methods, such as curvature comb, zebra crossing, as so as continuity accuracy of matched surfaces, a comprehensive evaluation method of auto-body surfaces based on FAHP(Fuzzy Analytic Hierarchy Process) is proposed, the specific comprehensive evaluating process is also given, and finally the validity and feasibility of the method is proved by some examples. |
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