Research On Surface Reconstruction Of Reverse Engineering

Face to the covering panel of automobile and motorcycle, appliance wiring and mobile telephone that have complex surfaces, sculpt design can't be completed by tradition design method, reverse engineering emerges as the times require. Reverse engineering is a process of gaining digital model from prototype, its peculiarity is shortcut, convenience and intuition, especially it fits for the production sculpt design. Its basic step includes: data measure of model surface, points pretreatment, reconstruction surface model, and the digital model export.Along with development of compute and photoelectricity technology, the data measure of reverse engineering is apt to use 3D optical-scanner. 3D optical-scanner's peculiarity is shortcut, high precision, large numbers of points, the scanner can measure 15000 points per second, and these points can fully express geometry character of model. The large numbers of points are called "point cloud"; the technology of establishing surface model base on point cloud is call "surface reconstruction".The content of surface reconstruction includes the arithmetic of surface fitting and the method of surface reconstruction. The NURBS surface has developed to pop arithmetic in the surface fitting, and has become the currency standard of CAD/CAM system, but the surface reconstruction has many disfigurements. At present, the surface reconstruction mainly depends on alternant modeling. Distinguishing characters of surface model, Mastering the balance of the smooth and precision, these works depend on the experience and skill of modeling man. The rules and methods lack the system induction and summarize. The methods of surface reconstrution have become "black skill" in control of a few man, the status has influenced the popularization of reverse engineering.After studying many of documents and information of surface reconstruction, and analyzing and bringing to practice, the circle gives some points facing the surface reconstruction base on the point cloud:1 Different production has deferent request of smooth and precision, especially the covering panel that request elegancy sculpt, pays attention to smooth of surface.2 In the every step of surface fitting, the layout of geometry character is emphases pre-fitting, choice for the appropriate arithmetic and parameter is keystone in the courses of fitting, and continuum of surface must be noticed after fitting.3 Surface reconstructions have better circumfuse the "character line". "Character line" is the borderline of point area and surface model, it likes the framework of surface model, and it can divide the point cloud. By insuring the quality of surface fitting and continuum between of surfaces, a integrity model can be reconstructed.4 Considering point treatment of Surfacer 10.6 and surface modification of UG NX, the reveres modeling may use two soft wares assistly.These methods are brought to reconstructing surface model of motorcycle covering panel, and the result approvers these methods are effective.