Geant4 Monte Carlo simulation relies on the Constructive Solid Geometry (CSG) method for complex geometric modeling. This method has low efficiency and a high application threshold. Importing triangular facet formats such as STL/OBJ via CADmesh is a promising alternative, but systematic evaluations of format compatibility, geometric accuracy, and physical simulation deviations are lacking. Construct open-source experimental environment based on Geant4 11.0, CADmesh 1.3.0 and FreeCAD 1.0. We design high and low precision gradient test cases using simple geometric bodies and complex engineering models, and systematically evaluate the import success rate, facet loss rate, volume error, and particle transport dose deviation for STL and OBJ formats.The results show a 100% import success rate for both formats; the volume error rate is <= 0.018% for high-precision models and <= 0.288% for low-precision models. The two formats share the same vertex facet data structure. This study designs a general adaptive interface. The interface reduces the number of parsing code lines by about 70% and maintains geometric accuracy.Furthermore, the tetrahedral mesh loading takes 3.1 times longer than tessellated solids, but the simulation time can be reduced from 15194.3 s to 77.28 s.

翻译：Geant4蒙特卡洛仿真依赖构造实体几何（CSG）方法进行复杂几何建模，该方法效率低且应用门槛高。通过CADmesh导入STL/OBJ等三角面片格式是一种有前景的替代方案，但缺乏对格式兼容性、几何精度及物理仿真偏差的系统性评估。基于Geant4 11.0、CADmesh 1.3.0和FreeCAD 1.0搭建开源实验环境，利用简单几何体与复杂工程模型设计高、低精度梯度测试用例，系统评估STL与OBJ格式的导入成功率、面片丢失率、体积误差及粒子输运剂量偏差。结果表明：两种格式的导入成功率达100%；高精度模型体积误差率≤0.018%，低精度模型体积误差率≤0.288%。两种格式共享相同的顶点面片数据结构。本研究设计通用自适应接口，该接口将解析代码行数减少约70%并保持几何精度。此外，四面体网格加载耗时较镶嵌实体增加3.1倍，但仿真时间可从15194.3秒降至77.28秒。