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太志伟, 张兴龙, 尹晓龙, 沈恩亚, 王建民. 三维船舶模型边界表示转构造表示方法[J]. 计算机辅助设计与图形学学报, 2023, 35(12): 1851-1862. DOI: 10.3724/SP.J.1089.2023.2023-00019
引用本文: 太志伟, 张兴龙, 尹晓龙, 沈恩亚, 王建民. 三维船舶模型边界表示转构造表示方法[J]. 计算机辅助设计与图形学学报, 2023, 35(12): 1851-1862. DOI: 10.3724/SP.J.1089.2023.2023-00019
Tai Zhiwei, Zhang Xinglong, Yin Xiaolong, Shen Enya, Wang Jianmin. A Method for Transforming B-Rep of 3D Ship Models into CSG[J]. Journal of Computer-Aided Design & Computer Graphics, 2023, 35(12): 1851-1862. DOI: 10.3724/SP.J.1089.2023.2023-00019
Citation: Tai Zhiwei, Zhang Xinglong, Yin Xiaolong, Shen Enya, Wang Jianmin. A Method for Transforming B-Rep of 3D Ship Models into CSG[J]. Journal of Computer-Aided Design & Computer Graphics, 2023, 35(12): 1851-1862. DOI: 10.3724/SP.J.1089.2023.2023-00019

三维船舶模型边界表示转构造表示方法

A Method for Transforming B-Rep of 3D Ship Models into CSG

  • 摘要: 模型数据表示是CAD几何引擎的基础,边界表示(B-Rep)和构造实体几何(CSG)表示是常用的2种模型数据表示方法,随着混合建模的发展,B-Rep和CSG混合建模开始应用于船舶等模型量大的场景,其中B-Rep与CSG实体的互相转换是一个关键性功能.针对类型多样的基本实体的B-Rep转CSG问题,设计了解析B-Rep几何结构并根据拓扑结构组合为CSG实体的转换流程.针对复杂实体的B-Rep转CSG问题,根据凹凸性将实体划分为不同类型的区域,将区域的边界作为切割环,据此提出了切割环识别算法.基于切割环识别,设计了二叉分解树进行实体分解和CSG树生成流程.对15种基本实体以及4个复杂模型的若干B-Rep实体,测量了其转换为CSG实体的转换误差和转换时间.实验结果表明,模型尺寸归一化后,文中方法可以在0.05%模型尺寸的误差范围内完成B-Rep实体向CSG实体的转换,并已支撑船舶产品设计系统(SPD)的部件小样建模平台的模型轻量化功能.

     

    Abstract: Model data representation is the foundation of the CAD geometry engine. The Boundary Representation (B-Rep) and Constructive Solid Geometry (CSG) representations are two commonly used model data representation methods. With the development of hybrid modeling, B-Rep and CSG hybrid modeling has been applied to large-scale models such as ships and the conversion between B-Rep and CSG is a key function. For the B-Rep to CSG conversion of primitives, a process was designed to parse the geometry structures in a B-Rep entity and combine them into a CSG primitive based on the topological structures. For conversion of complex entities, faces in a B-Rep entity are divided into different regions based on its convexity, and the boundary of each region is a cutting loop. Then a cutting loop recognition algorithm is proposed. Based on the cutting loop recognition results, a binary decomposition tree is designed for entity decomposition and CSG tree generation process. Fifteen types of basic entities and four complex models are used to make several B-Rep entities, and the conversion errors and time costs are measured. Experimental results show that the proposed method can achieve B-Rep to CSG conversion within an error range of 0.05% of the normalized model size, and has supported the model light-weighting function of the component sample modeling platform of the Ship Product Design System (SPD).

     

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