摘 要
随着CAD/CAM/CAPP一体化技术的发展，要求几何模型能够表示包含体现产品设计意图和功能的高层次的工程信息，因而出现了同时面向设计过程和制造过程，包含产品工程信息的几何造型方法，即特征造型(Feature Modeling)。随着特征造型技术在机械领域中的应用越来越广泛,对于反求工程也提出了对于特征提取的要求.本论文提出在反求工程中点云数据拉伸曲面特征提取的一种方法.首先,估算点云的主曲率和主方向,计算最小主方向的平均方向;利用去除含有与最小主方向平均值相差最大的点的方法进行噪声处理,在此的基础上得到曲面的拉伸方向;上述是得到拉伸方向的原理,我们可以利用计算机技术实现.把三标机测量机对实物测量所得的数据通过IGES的格式输入到编译的REFIT程序,实现计算机与软件的通信.在REFIT软件中在拾取点云之后,通过以上的算法,提取拉伸的方向.REFIT软件是以Microsoft Visual C++ 6.0为编译平台,实现的语言是C++.
关键词:反求工程,特征造型,曲面特征,拉伸方向
Abstract
Since cad/cam/capp develop close-coupled, the mold is required for the fuction which can express the products design purpose.then there comes a new method to design model,it turns in the direction of design process and making process.this is named Feature Modeling. This paper gives out one method to get the feature of the extruding surface of the point cloud. First at all, estimate the average value of the main curvature and the main direction; then, calculate the average value of the min direction of every point of the point cloud . Do the filtration which kicks out those points have long distance to the average value of the min direction. On the basis of last step program can get initial direction of the extruding surface. All the words above are discussing the theory , and now that can use the computer to move the theory to the reality. The data which is measured from Three Coordinate Measuring Machine transforms to the format of IGES . then guide into the program named refit . It finishes the communication between the software refit and computer. The program finishes three steps ,the first is getting data, the second is reaching arithmetic , the third is getting the result. By the way ,refit uses Microsoft Visual C++ 6.0 as the platform and the computer language is c++.
keywords: Reverse Engineering , Feature Modeling ,the feature of the extruding surface ,the direction to extrude ,
