[Gate-users] Rectangular Prism With Curved Edge

[David Sarrut]

Hello,

I agree with John. To my knowledge, tesselated solid is not accessible in
Gate.

However remember, Gate is nothing else than a shared, collaborative, pure
Geant4 application, so everything available in Geant4 could be added in
Gate. If nothing already available in Gate directly suits your problem, my
advice is to start studying your specific situation with additional Geant4
code in your own Gate repository. For example, you may want to add a new
type of volume (inherit from GateVVolume that uses G4Physical and
G4LogicalVolume).

If it appears that this new volume could be of interest to other people,
feel free to propose a pull-request so as we can integrate it in next Gate
releases.

David



On Wed, Jun 10, 2015 at 4:56 AM, John Apostolakis <John.Apostolakis at cern.ch>
wrote:

>  From the perspective of a Geant4 Geometry developer:
>
>  1) One alternative available in ‘native’ Geant4 is to use a ‘Tesselated
> Solid’, which allows you to create a solid using its surfaces.  Those can
> be either triangles or quadrilaterals. This may or not be available in GATE
> (the experts can advise).  If not, it should be possible to add it as a
> shape, within a measurable effort.
>
>  One advantage of this shape is that the implementation has recently been
> redone, and the CPU performance is greatly improved compared to the
> original version, which had to test all the surfaces.
>
>  2) Regarding the idea of using 600 boxes: the Geant4 Navigator (which
> GATE uses) is easily able to handle thousands of volumes placed at the same
> level of the geometry.  This capability is used by the geometry of large
> High Energy Physics experiments, and is instrumental in obtaining adequate
> CPU performance for them.  So having 600 boxes at the same level will not
> stress it.  Of course it will not be as fast as a geometry with 6 or 60
> boxes - but the most important reason is the increased number of steps,
> since steps will stop at volume boundaries.
>
>  [ It may be possible to tweak the CPU performance using a parameter in
> the volume in which you place these, if you wish to obtain some
> improvements. Please refer to the Geant4 manual for information about this
> - again this option may require some code change in GATE to access . I
> would expect around 10% change, if any, doing this from prior experience.
> Unexpected improvements would be of interest! ]
>
>  Hope this helps,
>      John A
>   ===================================================
> John Apostolakis,  PH Department, CERN
>
>       On 10 Jun 2015, at 01:26, Karl Spuhler <karl.spuhler at stonybrook.edu>
> wrote:
>
>  Hello,
>
>  I need to model a curved filter. I am wondering if this is possible? It
> will have different thicknesses at 600 points. I suppose I could use 600
> different boxes, as I have calculated the thickness of each cross section
> in Python, but I am concerned that this might make the simulation run for
> too long.
>
>  --
>  Karl Spuhler
>
>  SUNY Stony Brook
> PhD Student
> (845)249-6836
>
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>
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-- 
David Sarrut, Phd
Directeur de recherche CNRS
CREATIS, UMR CNRS 5220, Inserm U 1044
Centre de lutte contre le cancer Léon Bérard
28 rue Laënnec, 69373 Lyon cedex 08
Tel : 04 78 78 51 51 / 06 74 72 05 42
http://www.creatis.insa-lyon.fr/~dsarrut
_________________________________
 "2 + 2 = 5,  for extremely large values of 2"
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