User Manual

Based on XML syntax, the Geometry Definition Markup Language (GDML) is the reference language used to describe geometrical models (i.e. CAD models) for radiation modelling tools like Geant4, ESA/GRAS or SPIS-IC. GDML is based on a rich CSG approach and can be used to create complex and realistic geometrical systems to be used for various purposes.

As an XML-based language, it can be fairly well read by humans and it is quite simple to parse it. However, one of its limits is that it is difficult to visualise what a GDML file is going to produce just by looking at it in a tailored sense, i.e. as a 3D geometrical system. Although some viewers or editors exist, only a few of them are publicly available, and they are not user-friendly or incomplete. Moreover, most GDML editors so far cannot handle the depth hierarchy used in GDML.

Therefore, Artenum decided to develop a GDML editor based on the Keridwen IME. Its aim is to propose a simple-to-use, cross-platform editor with good capacities of visualization.

EDGE can either create or load a complete GDML model. In both cases, the user can modify the properties of all the shapes or add new shapes. Moreover, shapes also have position and orientation properties that allow placing them correctly. To facilitate the work for the user, position and orientation can be applied to several objects at the same time. EDGE handles complex hierarchies with several levels of depth.

EDGE also allows editing and attributing material properties to each shape individually. At any time, the user can see the results of his work thanks to the real-time 3D.

After editing his file, the user can save the result back to GDML but he can also export it to the B-Rep .geo format (the file format of Gmsh).

EDGE support natively the GDML format in reading and writing, but is also able to import numerous B-Rep CAD formats like Gmsh’s geo or STEP-AP 203/214 and tessellated solids in STL or UNV files. These import/export capabilities open interoperability bridges with other CAD tools and multi-physics simulation software.

EDGE is able to convert GDML models into an equivalent Gmsh’s geo file, fully compliant with tailored applications like SPIS. This conversion is not done by tessellation but by a proper CSG to B-Rep decomposition with the view in Gmsh (on the left) of a model initially defined in EDGE (on the right).

The present document is intended to be a simple User Manual (UM) to help the user to use EDGE in basic mode to create CAD modelling. This document does not attempt to provide to the future EDGE user the whole expertise and knowledge needed to create a correct CAD modelling. The final confidence in the relevance and accuracy of the CAD model depends on the user expertise and remains his responsibility.

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