| Automotive industry is a technology-intensive and matured industry, it is a good carrier for many leading techniques. Also we know that the product development is the kernel of automotive technology. With more than ten years' improvement, the improvement of integrated technology has a large speed and keeps along with the international advancement. The technology of computer and information have been used in automotive design and development wider and wider. From "throwing off the T-square" to 3D digital design, we have stepped into a new area in new product development process.As we all know that there is a big gap between our national automotive industry and othersËŠ .Reverse engineering is an emerging technology that promises to play a role in reducing production development time. Reverse engineering in this paper refers to the process of creating engineering design data from existing parts. It creates or clones an existing part by acquiring its surface data using measuring device. Techniques in reverse engineering have make great progress ,but there is a "bottle-neck" in reverse engineering that we have to handle the large amount of point data at the beginning of reverse engineering. At the same time we should develop an adaptive measuring plans in measuring the surfaces of existing parts too .Today there is a great progress in free form surfaces design ,and all of this bring more and more requests to the quality of autobody surfaces model too .To maintain the design quality and make direct integration of reverse engineering and rapid prototyping. This paper depicts a new concept, the non-uniform grids subdivision based on Octree system. The main content about it is describes as following .In chapter one ,the paper reviews the development the digital system. It introduces the merits and demerits of the contact measuring system. Recently, laser scanning and structured light have improved significantly and have become a viable option in capturing geometries of complicated design models. However they generate up to thousands of point data per second, and handling the huge amount of point data is a major problem, and it is difficult to capture the information between the neighbor points ,so it becomes quite important to reduce the number of the point data. Now many researchers have devote themselves to this job. Then it introduces the research of this paper.In chapter two based on mathematical models it introduces the theory of the measuring system. In optical measuring system, using hotogrammetry ,the position of a 3D space can be determined by triangulation multiple bundles of observation rays. The camera models is used to describes the projection of an object onto the image plane of a camera, this model is based upon a pinhole perspective device with the camera as the pinhole.In chapter three, give a study on different reduction methods. The algorithms based on point clout directly is simple and efficiently, but it does not take the shape of the surfaces into account, so it cannot keep the shape of the boundaries and the areas that a significant curvature change occurs. STL file format as the standard input for all rapid prototyping and manufacturing (RP&M) is generated by tessellation of surface and solid models, so some of the algorithms aims to generate the optimal STL file. Triangulation net is first generated form origin point cloud and then remove the triangles on the planner area based on some criterion .Delaunay triangulation is applied on the remained points. Based on the aforementioned work, the paper in chapter four presents the algorithms based on octree structure. First, the geometric information of each point data ,such as normal vector and principal curvature ,is calculated. Then, a 3D boundary that contains all scan point data is defined and initial cells within the boundary are generated. Based on the geometric features of scanned object around sharp or smooth edges, standard deviation of point normals or principal curvatures in each sell is used as the id...
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