A CAD/Geant4 Front-end Interface
Fan Lei
Space Department, Defence Evaluation & Research Agency,
Farnborough, UK
Rodolfo Gurriaran
Department of Physics & Astronomy, University of Southampton
Southampton, UK
(Some images and data in this presentation courtesy of PDES Inc.)
Spacecraft Environment & Protection Group
GEANT4 Workshop, ESTEC, 20-24, Sep. 1999
Introduction
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A front-end user interface to allow space engineers to import CAD model
into the Geant4 based space radiation shielding calculation tools.
The development process has been divided into two phases
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Phase I: Investigate compliance of major CAD tools with STEP protocol or future trends in
this direction. Define a set of user requirements for a CAD front-end interface for the space
radiation effects community. Assess their possible application as a front-end for
geometry/material definition for G4 based tools.
Phase II: The design and development of the front-end interface. The final esign is a
combination of a CAD system and a Material Generation & Association tool. The later is
adapted from GGE.
The work has been carried out by University of Southampton
Spacecraft Environment & Protection Group
GEANT4 Workshop, ESTEC, 20-24, Sep. 1999
Spacecraft Environment & Protection Group
GEANT4 Workshop, ESTEC, 20-24, Sep. 1999
Spacecraft Environment & Protection Group
GEANT4 Workshop, ESTEC, 20-24, Sep. 1999
Some Comments
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AP203 ISO standard since 1994
The compliance of CAD systems is evolving fast
Many CAD system claim to be compliant, but in reality only partial
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some “old” STEP files forget the “management” information (class1)
AutoCAD R15 partially implement class1, not class 3 nor 5.
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CATIA the first to be certified conformant with the STEP international standard (AP203)
PDES generated a “Recommended Practices for AP203” in 1998:
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class 1 is required.
For this work, class 1 “management information” must be present (“PRODUCT”
field)
Spacecraft Environment & Protection Group
GEANT4 Workshop, ESTEC, 20-24, Sep. 1999
Evaluation of CAD status
CAD Product:
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ProEngineer (Parametric)
Euclid (Matra Datavision)
Catia (IBM Dassault)
MicroStation (Bentley)
AutoCAD (AutoDesk)
I-deas (SDRC)
Suitability for G4 based application:
yes
yes (with translator)
yes
translator released ?
yes (R14.01 +)
yes
It is not possible to use a CAD system to define and manage the material
information as required in Geant4
Spacecraft Environment & Protection Group
GEANT4 Workshop, ESTEC, 20-24, Sep. 1999
G4 STEP reader
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Based on a free tool from NIST
Instantiate geometry in STEP file as G4LogicalVolumes
limitations :
– accesses only geometry information, does not access the “management”
information, i.e. the class 1 data.
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How to associate material to each volume ?
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To enhance the reader to read the class 1 information
temporary solution: use the sequential coincidence between volumes in step file and mga
file.
Spacecraft Environment & Protection Group
GEANT4 Workshop, ESTEC, 20-24, Sep. 1999
Front-end User Interface
The Interface consists of
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An off-the-shelf CAD system: for geometry modeling. The design is
outputted in a STEP file.
The Material Generation & Association (MGA) tool: allow user to define the
materials and associate them with volumes in the STEP file. The results are
outputted in a MGA file.
The STEP and MGA files will be used to define the geometry in a G4
application automatically.
Spacecraft Environment & Protection Group
GEANT4 Workshop, ESTEC, 20-24, Sep. 1999
G4 Application Using
STEP & MGA Files
STEP file
MGA file:
Materials definition
Colours
associations
Reader module
- Instantiate volumes
- Instantiate materials
- Instantiate logical
volumes
Requirement on STEP file format:
• AP 203
• Volumes are named
• A description of material is
desired.
MGA file format:
See the document: UoS-rep-05
Routine inside G4 Application
Spacecraft Environment & Protection Group
GEANT4 Workshop, ESTEC, 20-24, Sep. 1999
MGA
Database of pre-defined
space materials and predefined colours.
Creation of internal
databases (materials and
colours)
User defined volume names
Materials definitions
Design of the MGA
tool is based largely on
GGE: the G4 geometry
editor.
Visualisation definitions
CAD Tool
Of the shelf CAD application
STEP file
Spacecraft Environment & Protection Group
GEANT4 Workshop, ESTEC, 20-24, Sep. 1999
Association of :
Materials
colours
volumes
MGA application
MGA file:
Materials definition
Colours
associations
Future Work
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Enhance the G4 STEP reader: compliance to AP203
class 1.
More tests with variuous types of STEP files from ESA,
created by different CAD tools.
Integration of MGA/GGE?
Commit the proper G4mgareader to the G4 repository.
Documentation.
Spacecraft Environment & Protection Group
GEANT4 Workshop, ESTEC, 20-24, Sep. 1999
Relevant Documents
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G3 and CAD systems (UoS-rep-01)
GEANT4 and CAD systems (UoS-rep-02)
Following documents can be found in DERA web pages:
http://www.space.dera.gov.uk/space_env/geant_docs/geant_docs.html
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URD CAD-Tool Front-End to GEANT4/SPARSET (UoS-rep-03)
Discussion Document on the General Design of the CAD Front End Tool (UoS-rep-04)
Development of GGE to perform materials and visualisation attribute definition in the CAD tool
front end (UoS-rep-05)
SSD CAD Front End Tool for GEANT4/SPARSET (UoS-rep-06)
Spacecraft Environment & Protection Group
GEANT4 Workshop, ESTEC, 20-24, Sep. 1999