CERN Program Library Long Writeup W5013 - CERNLIB ...

4 Usage
In order to carry out a successful transfer of a detector model, a user needs to be aware of certain limitations
of the interface. The user is recommended to communicate with the engineers using CAD systems to
establish a proper transfer methodology. If a CAD system is not capable of receiving the whole detector
geometry in a single SET file, a user can transfer a detector model in smaller parts. These parts can then be
joined together in the CAD system. Normally it is a good idea to just export one instance of each division
in order to limit the number of exported volumes. The divisions can be reproduced in CAD systems. It is
impossible to give an exact size-limit for a detector model which can be transferred in one file, because the
limitation depends on the structure of the detector model.
The GEANT graphics package provides excellent capabilities for viewing parts of a detector model which is
to be exported. Using the visibility attribute and the number of division instances, a user will be able to
see what is to be exported. A user can use different colors in order to help to distinguish different volumes
(eg division instances, etc.) in a CAD system. Dummy volumes, such as mothers made of air or vacuum
should be suppressed using the visibility attribute, since the interface is currently not able to discard such
information. A user must remember to specify the drawing parameters again if he wants to draw the detector
model after using the interface. This is because the interface uses modified drawing routines.
A plot of the GEANT tree can be useful for engineers to understand the structure of the GEANT detector model.
GEANT volume names are useful references regarding the material and tree information. The tree information
is also provided in the material file, but a graphical presentation is often useful.
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