RE: [fluka-discuss]: Trying to use geometry out of stl-format

From: Chris Theis <Christian.Theis_at_cern.ch>
Date: Mon, 24 Feb 2014 10:58:32 +0000

Dear Kilian,

yes, FLUKA requires you to define geometries in terms of CSG = boolean operations applied to the basic primitives like sphere, cylinder etc.
3D wavefront or STL files would require a completely different kind of primitive which is not supported in FLUKA.

Even if this primitive was supported then there would be another subtle issue which most people are not aware of and that is closure & validity. Creating and exporting a 3D surface model which is suitable for particle transport is in principle possible but it is far from trivial. Due to missing numerical accuracy one can easily create tiny holes in the model, which you won't notice during visualization. However, they will practically prevent accurate particle tracking and could cause particles to simply vanish, distort energy conservation etc.

Cheers
Chris

-----Original Message-----
From: Kilian Baumann [mailto:baumann.kilian_at_gmail.com]
Sent: 24 February 2014 11:13
To: Chris Theis
Cc: fluka-discuss_at_fluka.org
Subject: Re: [fluka-discuss]: Trying to use geometry out of stl-format

Dear Chris,

thank you very much for your answer!
So in fact this means, that the only possibility to create a geometry in FLUKA is to use the given bodies like spheres, cylinders, planes and cones? Are there no other ways to import directly geometries like 3D-wavefunction (.obj) or other files of this kind to FLUKA?

Thanking you in advance!

Best regards,

Kilian

2014-02-23 20:26 GMT+01:00 Chris Theis <Christian.Theis_at_cern.ch>:
> Dear Kilian,
>
> I'm afraid that SimpleGeo provides some features (e.g. surface or b-rep models) which are not supported by FLUKA at all. Currently you can only use those models as a mockup or 3D template in SimpleGeo, while modelling your actual geometry with CSG methods. This way you can ensure that the geometry that you've built is matching a 3d CAD model for example. However, you cannot simply export the CAD model via SimpleGeo to FLUKA because this type of surface models is not supported by FLUKA's geometry kernel.
>
> Cheers
> Chris
>
>> On 23 Feb 2014, at 16:31, "Kilian Baumann" <baumann.kilian_at_gmail.com> wrote:
>>
>> Dear fluka-experts,
>>
>> I have a complex geometry, described in a stl-file. Since this kind
>> of file is not compatible with FLUKA (stl just describes surfaces) I
>> converted this stl-file to a 3D-Wavefront (obj) file. When impoting
>> this file to SimpleGeo there are no problems. I can edit names,
>> materials, positions, etc. However when exporting my geometry to an
>> input-file for FLUKA it does not work, since the with SimpleGeo
>> defined region (my obj-file) does not link to any body. So is there
>> any possibility to define a new body out of my obj-file? Because with
>> this new body I could create my region. Or is there any other way,
>> how I could define my geometry with the obj-file?
>>
>> Thanking you in advance!
>>
>> Best regards,
>>
>>
>> Kilian
>>
Received on Mon Feb 24 2014 - 13:00:25 CET