Hello Matthias,

Thanks for the tip. I've taken a quick look at the code and  it
doesn't seem to compute intersections anywhere. Apparently OCC has some
functionality to do this by itself... I feel really silly :-(

Unfortunately I also lack the time to work on gmsh. If nobody solves this
problem before I start using gmsh again I will have a look at netgen and
if it works port the code to gmsh... but I doubt it will happen this year.

regards,

Mark van Doesburg

"Zenker, Dr. Matthias" <[email protected]> wrote:

        Hi Mark,

        just in case you are still interested in that topic:
        I have briefly tried to find out how this is solved in Joachim 
Schoeberl's netgen. As far as I understand, he uses OpenCascade for his 
"geometry healing", which i have already used successfully to repair those 
double surfaces. Looking into the netgen source, there is a method HealGeometry 
in occgeom.cpp. I don't have the time to delve into the gmsh code an see how 
this functionality can be incorporated there. But since you have already done 
gmsh programming, it may be much less effort for you to try this out.

        Best regards,

        Matthias

        -----Ursprüngliche Nachricht-----
        Von: Mark van Doesburg [mailto:[email protected]] 
        Gesendet: Montag, 13. September 2010 09:58
        An: Zenker, Dr. Matthias; [email protected]
        Betreff: Re: [Gmsh] Double surfaces after STEP import

        Hello Matthias,

        I worked on that code and consider it a complete faillure. In many 
cases the OpenCASCADE algorithms would not find the intersections. The initial 
version was quite simple but at some point I started to stack one workaround on 
top of the other.

        Currently I do not have the time to work on another method, but some 
algorithms available in CGAL look promising. But in that case I would probably 
use BRL-CAD to generate the geometry, and importing STEP into BRL-CAD might be 
sub-optimal.

        regards,

        Mark

        "Zenker, Dr. Matthias" <[email protected]> wrote:

                Hi,

                I have not done FEM calculations for some time (a year or so). 
The last
                time I did them (using gmsh and Elmer), I had the problem that 
in
                geometries imported as STEP files (generated by Solidworks), 
adjacent
                bodies have their own external surface, resulting in double 
surfaces at
                the interfaces. When I use the mesh generated by gmsh in a FEM
                calculation (I use Elmer), I get no thermal and electrical 
connection
                because the body meshes are not connected at the interface. 
There have
                been attempts to clean up double surfaces in gmsh, but I don't 
know if
                they have come to a success. Could someone of the developpers 
update me
                on this point?

                Thank you!

                Matthias 

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