Research On Key Technologies Of Surface Reconstruction From Measured Points

Reverse engineering is one important way of product creative development and rapidmanufacture, which is widely used in automobile, home appliances, mould, entertainment andmedical treatment. As the key technology of reverse engineering, surface reconstruction isalways a hot research topic. For the issues of theory of surface reconstruction and itsapplications, several key technologies of surface reconstruction and its applications intool-path generation from measured points are systematically studied and implemented in thisdissertation. Mesh topology reconstruction is one of the key technologies of surface reconstruction.To rapidly obtain a reconstructed mesh with the same topology as product shapes, analgorithm of interpolating mesh boundary incremental construction is presented based onlocal 3D-Delaunay (MBIC), which constructs the mesh with the same topology as the localshape through 3D-Delaunay triangulation of local points, rapidly promulgates local meshconstruction to all the points through incremental operations of the reconstructed meshboundaries, and automatically reconstructs hole features when the incremental operationsends. Some portions of the product surface can be incomplete in surface reconstruction. Usually,the missed surface areas include some important form features of the product. To repair thoseform features, an incomplete data repair method is described using deformable model underconstraints of given feature forms. The method ensures the correctness of identifying themissed local areas by choosing a set of proper rules of mesh construction according to thedensity entropy of measured data, and fills them with an energy-based deformable local meshsatisfying the constraints of feature shapes that indicates the design intents of measuredproduct. Product form features reconstruction is determined by the method of data segmentationand surface feature recognition and approximation. To properly reconstruct product formfeatures, a method of data segmentation and feature surface reconstruction based on featuremembership is put forward. In this method, the constructed mesh is subdivided into subset bythe topology rings of boundaries extracted with feature boundaries membership, the formfeature of subset is recognized and fitted with form feature membership, which nicelyrecovers the product form features, and in favor of the whole product features and constraintsreconstruction. Tool-path generated directly from measured points is studied, and an algorithm of IItool-path generation from measure points is proposed based on constraint quadratic errormetrics (CQEM). On the base of mesh topology reconstruction, this algorithm saves muchmemory and time by dynamically constructing mesh interpolating local points of toolaccording to its size, and reduces machining error by optimizing C-C points using CQEM. As an application of the above research, a prototype system of surface reconstructionfrom measured points–––InteReSolid has been accomplished, and embedded into 3D-CADsystem––– InteSolid2.0, which supported by the National Key Research Project of the 10thfive- year-plan of China (Grant No. 2001BA201A02).