Evaluation of CAD status

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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.)
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Introduction

• 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
• 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

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Some Comments

• 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
• some old STEP files forget the management
  information (class1)
• AutoCAD R15 partially implement class1, not class
  3 nor 5.
• CATIA the first to be certified conformant with
  the STEP international standard (AP203)
• PDES generated a Recommended Practices for
  AP203 in 1998
• class 1 is required.
• For this work, class 1 management information
  must be present (PRODUCT field)

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Evaluation of CAD status

• CAD Product Suitability for G4 based
  application
• ProEngineer (Parametric) yes
• Euclid (Matra Datavision) yes (with translator)
• Catia (IBM Dassault) yes
• MicroStation (Bentley) translator released ?
• AutoCAD (AutoDesk) yes (R14.01 )
• I-deas (SDRC) yes
• It is not possible to use a CAD system to define
  and manage the material information as required
  in Geant4

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G4 STEP reader

• 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.
• How to associate material to each volume ?
• To enhance the reader to read the class 1
  information
• temporary solution use the sequential
  coincidence between volumes in step file and mga
  file.

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Front-end User Interface

• The Interface consists of
• 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.

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G4 Application Using STEP MGA Files

• 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

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MGA
Design of the MGA tool is based largely on GGE
the G4 geometry editor.
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Future Work

• 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.

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Relevant Documents

• 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
• 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)