[Gmsh] Some hints to solve self intersecting surface errors?

[Mario Ceresa]

Hi Matthias,
thanks for your mail. I tried to remove the smaller cilinder and indeed 
cut and merge does modify the geo, albeit in a strange way (there are 
volumes made of only one surface). It still segfault during 2d meshing.

Meshing joint2.igs *without* cut-and-merge still complains about 
self-intersecting faces.

I attach the iges model and the geo file saved after the import and the 
automatic cut and merge.

I wonder if the problem is that i create three separate solids which 
have touching surfaces. Maybe I'm not supposed to do so? If this is the 
case, which is the right way?

Thanks and regards,

Mario

On 08/19/2013 04:09 PM, Zenker, Dr. Matthias wrote:
> Hi,
>
> this is a known problem, and there exists no proper solution within gmsh (yet?).
> To see the problematic faces, you can merge the intersect.pos file gmsh generates. Then you can try to resolve the problematic faces directly in your CAD or by saving your input file in geo format and modifying that one.
> IF your case is not much more complicated than your testcase, it might suffice to resolve the partial overlap between the outer surfaces of the small and the large cylinder. If you omit the small cylinder (volume 3 in gmsh) for testing, does "cut and merge faces" work between the others?
>
> HTH,
>
> Matthias
>
>> -----Ursprüngliche Nachricht-----
>> Von: Mario Ceresa [mailto:mario.ceresa at alma3d.com]
>> Gesendet: Montag, 19. August 2013 10:14
>> An: gmsh at geuz.org
>> Betreff: [Gmsh] Some hints to solve self intersecting surface errors?
>>
>> Dear all,
>> My workflow is to use Sketchup to quickly create the geometry, export it as
>> iges and then mesh it with gmsh. Sometimes, usually when I have many co-
>> planar faces, I get the error:
>> "Self intersecting surface mesh, computing intersections"
>>
>> and meshing fails. I attach an example. I tried "Cut-and-merge-faces"
>> option but it segfaults during 2d meshing.
>>
>> Which is the proper way to solve this? Is there a way to "see" the
>> problematic faces so to know which parts of the geometry to change?
>>
>> Thanks and regards,
>>
>> Mario
>
>
> _____________________________________________________________________
> ERBE Elektromedizin GmbH
> Firmensitz: 72072 Tuebingen
> Geschaeftsfuehrer: Christian O. Erbe, Reiner Thede
> Registergericht: Stuttgart HRB 380137
-------------- next part --------------
A non-text attachment was scrubbed...
Name: joint2.zip
Type: application/zip
Size: 22842 bytes
Desc: not available
URL: <http://www.geuz.org/pipermail/gmsh/attachments/20130820/59579c3d/attachment.zip>