基于拉伸特征的B-Rep→CSG转换算法及其应用  

Stretch feature based B-Rep→CSG conversion algorithm and its application

作　　者：罗月童[1] 韩承村 杜华 严伊蔓 LUO Yuetong;HAN Chengcun;DU Hua;YAN Yiman(School of Computer Science and Information Technology,Hefei University of Technology,Hefei 230601,China;Institute of Plasmia Physics,Chinese Academy of Sciences,Hefei 230031,China;State Power Investment Corporation Research Institute,Beijing 100033,China)

机构地区：[1]合肥工业大学计算机与信息学院,安徽合肥230601 [2]中国科学院等离子体物理研究所,安徽合肥230031 [3]国家电投集团科学技术研究院有限公司,北京100033

出　　处：《浙江大学学报（理学版）》2021年第2期151-158,166,共9页Journal of Zhejiang University（Science Edition）

基　　金：国家重点研发计划项目(2017YFB1402200);安徽省科技攻关计划项目(1604d0802009);国家自然科学基金资助项目(61602146)。

摘　　要：边界表示(boundary representation,B-Rep)法和构造实体几何(construction solid geometry,CSG)法是目前应用最广泛的两种实体表示法,B-Rep→CSG转换也备受关注。B-Rep→CSG转换算法为一种半空间分割法,完全依赖三维造型引擎中的布尔运算,计算量大且不稳定。实际应用中已有大量具有拉伸特征的B-Rep模型:可将整个模型或模型的一部分看作由二维图形沿一定方向拉伸而成。通过将三维模型的B-Rep→CSG转换问题变为二维图形的B-Rep→CSG转换问题,从而避免对布尔运算的依赖,为此,提出基于拉伸特征的BRep→CSG转换算法。首先,得到拉伸边具有相互平行性、首尾相连性、方向相反性、唯一连接性4个拉伸特征,然后,基于这些特征提出基于平行边连接图的拉伸特征识别算法,最后,结合拉伸特征识别算法、基于环收缩的模型分割算法和基于顶点可见的多边形分割算法,提出具有拉伸特征的三维模型的B-Rep→CSG转换整体解决方案。将本文算法集成至自主研发的粒子输运可视建模(COSINE visual modelling of particle transport,cosVMPT)软件,并基于cosVMPT对3个专门构造的例题和1个实际应用实例进行了测试,测试结果证明了本文算法的有效性和优越性。Boundary representation(B-Rep)and construction solid geometry(CSG)are the two most widely used solid representation schemes,and B-Rep→CSG conversion has always been a theoretical problem of great concern.At present,the most commonly used B-Rep→CSG conversion is half-space decomposing algorithm,which vitally dependents on the underlying 3D modeling engine′s Boolean operation,and is limited due to intensive computation and instability.There are many stretch models in B-Rep model,which are formed by sweeping 2D drawing along a certain direction,and their B-Rep→CSG conversion can be transformed into B-Rep→CSG conversion of 2D model.In this paper,a Parallel Edge Adjacent Graph based stretch feature recognition algorithm is presented.The overall scheme of B-Rep→CSG transformation for 3D models with stretch features consists of stretch feature recognition,cutting loop shrinking based model decomposition and polygon vertex visibility based polygon decomposition.The proposed method is integrated into cosVMPT(COSINE visual modeling of particle transport),which is a visual modeling tool for particle transport software package.Three synthesis examples and a practical application example are used for testing.The testing results demonstrate the effectiveness and superiority of the proposed method.

关 键 词：B-Rep→CSG转换 拉伸特征 平行边连接图形 多边形分割 

分 类 号：TP391.41[自动化与计算机技术—计算机应用技术]