On 05 Mar 2012, at 23:56, Wayne Christopher wrote:
> Dear Gmsh Users,
>
> I would like to write a Step file (from my app which uses OpenCascade), read
> it into gmsh and create a mesh in batch mode, and read the msh file back into
> my app, associating the triangles and tetras with the original shapes.
>
> What I am seeing is that there is no PhysicalNames section in the output msh
> file, and the values of the physical names tag seems arbitrary. (Also the
> numbers used for triangle regions and tetra regions overlap).
>
If you did not define physical tags, then by default all the elements in the
mesh will be saved with
- an elementary tag that corresponds to the id of the geometrical entity they
discretize
- a physical tag == 0
> I'm assuming that the right way to handle this requires me to attach labels
> to the volume, surface, curve entities in the step file and somehow tell gmsh
> to use these labels as the PhysicalNames in the output file. Is this correct
> and if so how would I specify this?
>
Just create a .geo file that
- merges the .step file (Merge "file.step";)
- and defines the physical tags you want (Physical Volume("my volume") =
{1,2,3};)
By default, when physical groups are defined, only those elements that belong
to physical groups are saved.
> The other fly in the ointment here is that OpenCascade seems to ignore the
> labels I attach to sub-shapes and this seems to be a long-standing problem -
> see http://www.opencascade.org/org/forum/thread_14829 .. Has anybody dealt
> with this issue?
>
> Thanks for the help!
>
> Wayne
>
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--
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science
http://www.montefiore.ulg.ac.be/~geuzaine
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