曲面重构是计算机辅助设计和逆向工程领域中的研究热点,提出了一种基于平行轮廓横截面信息利用NURBS理论构造分支曲面实体的新方法.根据相邻横截面上轮廓线间的不同对应关系;如果是"一对一"的情况,可直接构造蒙皮曲面;如果"一对多"的情况,则转换为多个"一对一"的情形先构造包络面,再对包络面进行裁剪,利用四边Coons曲面片填充算法完成分支曲面的重构;如果是"多对多"的情况,则将之转换为两个"一对多"关系再来进行曲面重构.对多个连续的"一对一"关系复合蒙皮,提高了重构曲面的光滑度;通过添加方向导线,避免了额外的优化时间;把"多对多"转化为两个"一对多",降低了直接利用"多对多"关系构造曲面的复杂性;通过对参数区间的调整,实现了对中间带位置和宽度的灵活控制,为重构分支曲面的形状提供了可控性.%Surface reconstruction is significant in Computer Aided Design (CAD) and reverse engineering. A new approach of constructing solid branching surface model using Non-Uniform Rational B-Spline( NURBS) theory based on parallel contours was proposed. According to different relationships among adjacent contours, it could be divided into three cases, such as "one to one", "one to many" and "many to many". In the case of "one to one", a surface patch could be constructed by skinning method. To construct surfaces from "one to many" contours, the more "one to one" relations were exchanged from "one to many" case, from which envelope planes were constructed accordingly. After surface trimming, 4-sides Coons filling, one branching surface was reconstructed. In the case of "many to many", two "one to many" relations were converted from it to construct surface. By skinning multi-adjacent "one to one" relationship, the smoothness of the reconstructed surface was improved. And the extra-time of optimization was avoided by adding direction traverse. Complexity of constructing surface was reduced after translation from "many-to-many" case into two "one-to-many" case. Through adjusting the parameter, controlling of the position and width of the mid rip were realized. It provided controlability for shape of the reconstructed branch surface.
展开▼
