Point-Cloud Reducing Based On Bezier Curve Extension And Surface Fitting

Along with economic globalization, the new technological revolution and adjustment of industrial structure, the internationalization and automation of automobile production has become an inevitable trend. While the market share of China's own-brand cars has upgraded steadily year by year. The production of parts in China, Just seat will reach about 44.16 million by 2010. Therefore, the seats as an integral part of the car all have considerable prospects for the international market and domestic market. So the overall development of car industry is the development of productive integration of different parts, The design and manufacture of automobile parts has a relationship of the whole automobile industry chain development. From the parametric design of parts and automated production can be extended to the entire automotive industry, parametric design and automated production. From the actual project, this article tries to research the automation of auto parts modeling combining with current technology and hardware equipment.In the design and production of automotive parts, reverse engineering is one of the major technologies nowadays. Measurements of the model; to obtain data; analyzing data; reducing data; parametric surface reconstruction; creating a CAD model, processing into actual products. It needs every step of the involvement of labor, The difficulty is reducing and surface reconstruction of data information. In order to obtain a precise surface data information of the model, it is still widely used method of measuring surface parameters by hand. This not only requires a lot of manual input, but also a longer time of design。Popular technique is to use three-dimensional laser scanner to obtain large amounts of information points on the model surface now. Deal with such an enormous set of points of information and obtain the parameters of data points with a relatively small magnitude. The ability of reducing point cloud data is not reach to reducing information data based on the body characteristics of model-based block, still dealing with the data with the characteristics of a certain division in computer. The direction of modern reverse engineering efforts is that work out the impressive set of point-cloud using a computer and to use its automated to reducing information points. Point-cloud data reduction technique in this article is reducing noise points redundant points based on keeping the original in the shape of an object model as much as possible, To retain a relatively small number of information points In the surface tends to flat. To retain a relatively large number of information points in the Department of Big changes surface curvature or the different departments of components of splicing. I continue to regulate the different methods on achieving targeted to reducing parameter data on different surfaces in the process of reducing in using of procedures, the purpose is to maintain the maximum original objects. In the parametric surface reconstruction techniques, Reconstruction of the completion of surface rely on CAD-assisted design software (CATIA). We can design model with the artificial Information point in the past, I use relatively small number of reduced information points to reconstruct surfaces combining with the lofting technique of CATIA in the article.Use the point-cloud data in using the three-dimensional laser scanner in this article and read the information to computer. Firstly, process the point-cloud to different level in Y coordinate, the purpose is that making the points of point-cloud with similar threshold in the same coordinate to one set, then work out the distance of all points with each other with X coordinate and Z coordinate, judging the point nearby with the min-distance of above result. Sort the point set in the same level of Y coordinate to make a set of point sorted in a same direction. Firstly, reduce information point based on Line-method (using information of three points to judge whether the third point in the same linear made of first point and second point). Use is similar to the point of view - Strings Supreme Court's technical, to determine whether the three points on the same straight line in using of three consecutive points by the angle formed by two vectors arc to streamline the middle point out. And then reduce the so-called noise data points, using the average distance and the method of combining large coordinates, use procedures rotating display and CAD support to judge the jump point. Streamline the noise points out in a separate data. Finally, based on the extension of Bezier-curve, establish a Bezier equation in using Continuous four-point and extend out of the extension of this Bezier curve after the forth point. Read the X coordinate of the next fifth point in the program to work out the t of the above Bezier equation. And judge whether the Z coordinate of the fifth point is within this threshold worked out with t. If the Z is within the threshold, delete the forth point data from the point-cloud, if the Z is out of the threshold of the t, make Bezier equation in using the four points (from the second point to the fifth point). Reduce point in these three steps of the above methods, in quite targeted reducing method to planar data and surface data of model surfaces.IGES standard is the international exchange of common data model specification Applied to a lot of CAD / CAM aided design software. The purpose of using IGES standard is that making converted data can be in more use of graphics software platform. In order to the IGES standard and the structure of IGES file, and in order to the data indexing, and in accordance with paragraph marks and began section, global section, elements of the index segment, the parameter data segment, make the converted data from *.asc form file to *.igs form file which can be distinguished and used in CAD-assisted design software. Make the IGES three-dimensional point data to the midpoint of the data automatically in bulk .from the XYZ form of *. asc files to *. igs file format type conversion 116.Reverse Engineering of CAD model surfaces are generally a complex surface, often by a combination of different body surfaces. Large number of small patches formed splicing in a different shape in the surface. The use of point cloud data set is the overall model of the surface data set of points in the surface reconstruction will be split into different parts, the use of CATIA set of points from different parts of the proposed synthetic surface, and then stitching them into a complete surface model of the surface in this article. The use of CATIA is read *. igs file, read out a streamlined point sequence. Using Wireframe and Surfaces tools make the sequences linked into B-spline curve, Then use the lofting technique B-spline curve sequence fitted into NURBS surfaces.In this paper, VC-MFC with OpenGL technology, read, display, rotate zoom, streamlining point cloud data. The use of CATIA in related technology, surface reconstruction operation is complete. Depending on the respective work steps to perform different functions in the design process operation. Read the point cloud, display, rotate zoom, to streamline the design together, a more intuitive way to see each step of the point cloud data generated by the operation results. Conversion of data designed to be a separate module, *.asc automatically be converted into *. igs file. Part III to complete the reconstruction of the use of CAITA, save the file into a surface and can be displayed in the Master-COM.