断层测量反求工程中的关键技术

研究了由断层测量轮廓序列重构零件CAD模型的关键技术。根据截面的面积、形心位置等属性，并结合轮廓串匹配技术，提出了封闭轮廓集 分割算法。一个封闭轮廓由圆弧、直线段等规则形状的轮廓段和自由曲线段组成。为了抽取开放的规则轮廓段，提出了特征参数识别和特征轮廓抽取交互进行、有机结合的技术。为了抽取开放的自由曲线段，提出了基于转角映射的特征连接点辨识技术。进一步抽取开放轮廓集时，要解决相邻层上开放轮廓段的匹配问题，提出了基于串匹配的轮廓优化分割技术。实例表明，所提出的轮廓集分割算法可以实现规则形体表面和自由曲面对应开放轮廓集的精确分割。此外，文中对特征的分割策略、参数识别等问题提出了可行的解决方案。

Key Technologies of Reverse Engineering Oriented to Layer-Measuring Data

By comparing section properties such as area, center of figure, of different colsed contours, plus string-matching technology, an algorithm was presented to precisely segment certain closed contour set. One closed contour is composed of one or more elementary segments, such as line segment, circular arc and free-form contour. In order to further extract open contour segment, such as circular arc, from a closed contour, a technique that combines parameters identification and contour vertices extraction was put forward. For extracting free-form contour segment, another approach was presented to detect the join point between the interested contour segment with others based on turning angle map and B-spline fitting. When searching similar contour segments to seed contour from other layers, one optimal method based on curvature string-matching was put forward. Furthermore, in order to identify the parameters of individual surface/feature and reconstruct the global CAD models of measured parts, a practical solution was presented also.