Compatibility and Accuracy Verification of CADmesh-Based Complex Geometry Modeling in Geant4
For Geant4 users needing efficient complex geometry modeling, this work provides a systematic evaluation and a practical interface, but it is incremental as it applies existing methods to a specific domain.
The paper evaluates CADmesh-based complex geometry modeling in Geant4, showing 100% import success for STL/OBJ formats with volume error ≤0.018% for high-precision models, and reduces simulation time from 15194.3 s to 77.28 s via a general adaptive interface.
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.