CADMesh: a CAD file interface for GEANT4

Importing predefined CAD models into GEANT4 is not always possible or requires intermediate file format conversion to Geometry Description Markup Language (GDML) using commercial or third party software. CADMesh is a direct CAD model import interface for GEANT4 optionally leveraging VCGLIB, and ASSIMP by default. Currently it supports the import of triangular facet surface meshes defined in formats such as STL and PLY. A G4TessellatedSolid is returned and can be included in a standard user detector constructor. Robustness of the interface was tested using a set of CAD models of various complexity; for the models used in testing, no import errors were reported and all geometry was found to be navigable by GEANT4.Additional functionality is included for the fast navigation of tessellated solids by automatically creating equivalent tetrahedral meshes thereby making smart voxelisation available for the solid. Funding source: Cancer Australia (Department of Health and Ageing) Research Grant 614217将预定义的计算机辅助设计（Computer-Aided Design，CAD）模型导入GEANT4并非总是可行，若需导入则需借助商业或第三方软件，将模型转换为几何描述标记语言（Geometry Description Markup Language，GDML）格式的中间文件。CADMesh是一款面向GEANT4的直接CAD模型导入接口，默认以ASSIMP为导入后端，亦可选择性调用VCGLIB拓展功能。目前该接口支持导入STL、PLY等格式的三角面片表面网格，返回的G4TessellatedSolid对象可集成至标准用户探测器构造流程中。该接口的鲁棒性通过多组不同复杂度的CAD模型完成测试；针对本次测试所用的全部模型，未出现任何导入错误，且所有几何结构均可被GEANT4正常导航遍历。本工具还集成了额外功能：通过自动生成等效四面体网格，实现对细分实体的快速导航，进而为该实体提供智能体素化能力。本研究获澳大利亚癌症委员会（卫生与老龄化部）研究基金（编号614217）资助。