Research On Key Algorithms Of Triangulation And Application Of Triangular Net In Reverse Engineering

In reverse engineering,triangle net is not only the base of real objects surface reconstruction,but also plays an important role throughout the all stages of reverse engineering. Research on the techniques relative with triangle net construction and application has great significance to the development of reverse engineering.Aiming at the existed problems in reverse engineering techniques concerning triangulation method for scattered data points,display technique of three dimension model based on mesh simplification,and redesign technique for re-constructed surface etc.,this paper studies and proposes the relevant solving schemes,key algorithms and realizing technologies. The chief contributions acquired by this paper include:(1) An effective 3D triangulation algorithm for scattered data points is put forward. This algorithm solves the problem that data points must be partitioned for multi-projection realized by traditional 2D triangulation methods,and can also triangulate the scattered data points of trimmed surface and concave boundary surface. The four basic processing operations of 3D triangulation algorithm composed by boundary loop extending,splitting,merging and closing are summarized,the triangulation for any type of surface can be considered as the combination of these four basic processing operations,which makes the algorithm have great adaptability and can deal with scattered data points of diversified surface.(2) The concept of triangle net integrated optimization is proposed and the relevant algorithm is realized. With limited times of iterations by applying this algorithm,the integrated optimization,not only on geometric shape but also on space form,of triangle net can be obtained. The application results indicate that this integrated optimizing algorithm can bring out the best net topology with excellent triangular shape and net space form.(3) The concept and definition of generalized consistent triangle net is put forward. If all non-boundary edges have and only have two triangles mapping,left and right triangles,such triangle net is called general consistent. The concept ofgeneralized consistent triangle net extends the definition of consistent net of classical finite element theory,and loosens the triangulation operation's restrict,which makes the triangulation algorithm more flexible and adaptable.(4) A redesign approach for reconstructed surface based on triangle net template merging and sewing is firstly proposed and investigated. Some issues concerning the locating,size and angle matching for the net template relative to the model to be redesigned have been studied and the relevant algorithms have been realized. The approach can rapidly and effectively combine the existed excellent designs and produce the new product net model or surface model to realize the re-constructed surface redesign and the product innovation.(5) Considering the multiple applications of triangle net in reverse engineering,a succinct triangle net storage format is put forward and a sort of describing form using XML meta markup language is firstly presented for distributed calculating demanded by future's reverse engineering applications. In addition,triangulation result can be saved as STL file and straightly used by RP system.(6) The real time dynamic LoD model-generating algorithm of triangle net is studied. On the bases of existed algorithms,the functions of boundary points processing and form-keeping on boundary are added,and the relation between eyes-model distance and the resolution of simplified model is established.All of the algorithms and techniques presented in this paper have been realized and verified in a software system NPU-SRMS (NPU-Surface Remodeling System) developed by the laboratory author works at.