【作者】 刘军强；

【导师】 李言；

【作者基本信息】 西安理工大学 ， 机械制造及其自动化， 2004， 硕士

【摘要】 本文针对逆向工程中复杂零件表面的反求过程，提出对复杂零件表面按特征划分进行测量和曲面重构的反求路线。对实物反求过程中的各关键技术作了研究，包括：曲面的特征测量、逐行扫描测量数据的预处理、曲线曲面的特征表示及其拟合、曲面的特征识别以及曲面模型向CAD模型的转化。 对曲面的特征测量，采用曲面的自适应特征数字化方法解决采样数据的密度分配问题，对有标准参考坐标下和在不同参考坐标下的多视拼合问题，导出了坐标变换的公式并提出了数据拼合的计算过程。 针对大量含奇异点的数据点云，本文提出了剔除粗大误差的孤立点统计排异法，该方法根据对相邻点距离的统计，剔除在正态分布以外的点；对大量数据的精减，利用角度和弦高的最大允许偏差法进行点云精减。 对NURBS的直线、圆和圆弧、平面、柱面和球面等的表示方法作了理论研究，同时对NURBS曲线曲面的进行插值的计算，插值后的NURBS曲面，利用其表面局部微分几何特性，提出依据曲面的主曲率来提取特征面(平面、柱面和球面)的方法。 根据本文所涉及到的计算与模型的转换，以Windows 2000为操作系统平台，以VC++6.0为开发工具，结合OpenGL三维图形标准库，采用面向对象的设计方法完成一应用程序，该程序能够导入测量点数据并对其作相应处理，并将文中曲面数据以3DS的格式输出。更多还原

【Abstract】 In view of the process of reproducing of actual details in reverse engineering, a new process is proposed in this paper in which the surface of details is dividing by character in its measurement and reconstruction. According to this process, the key technology which including the characteristic measurement of surface, the pretreatment of data getting by line scan, the character expression and fitting of curve and surface, the characteristic identify of surface and translation from the model of surface to CAD.In the characteristic measurement of surface, a method of surface’ s self-adoption-character measurement is adopted in the paper to achieve the distribution of data’ s density. The formula of coordinate transformation is educed and the calculate process in data fitting is proposed.An isolated point’ s statistic excluding method is proposed in this paper to eliminate crassitude error in clouding data, which include plenty of oddity data. The method based on the distance between two neighbour points can eliminate the data beyond normal distribution. A error limitation of angle and chordal highness method is used to filtrate clouding point.The methods that represent geometry elements such as line, circle and arc, plan, cylinder, cone and sphere in NURBS form are studied. Meanwhile, the calculating process that interpose to NURBS curve and surface are advanced. To the processed surface, the paper brings forward a method to distill its character (plan, cylinder and sphere) by the main curvature of surface using its local differential coefficient geometry characteristic.According to the calculating methods in the paper, combining converting to CAD model, a application is completed using 00D technology, it base on Windows 2000 operating system, use VC++6.0 and OpenGL three-dimension graph standard as exploiting tools and can dispose the imported point data from outsides and export surface data in system as 3DS form.更多还原