[Gmsh] Error : Self intersecting surface mesh, computing intersections (this could take a while)
Steffen Becker
steffenbecker87 at yahoo.de
Fri Mar 14 21:09:16 CET 2014
Hi Matthias,
hm, I sent it on 12.03.2014 18:21, don't know what went wrong.
As you see, I created a ASCII .msh file as explained in the
documentation, so I hope it's correct.
What can I do now?
Steffen
Am 14.03.2014 13:05, schrieb Zenker, Dr. Matthias:
>
> Hi Steffen,
>
> there was no msh file in any of your mails.
>
> Depending on what is in the msh file, your steps seem correct to me.
>
> Matthias
>
> *Von:*Steffen Becker [mailto:steffenbecker87 at yahoo.de]
> *Gesendet:* Freitag, 14. März 2014 12:33
> *An:* Zenker, Dr. Matthias
> *Cc:* Roman Fratczak; gmsh at geuz.org
> *Betreff:* Re: [Gmsh] Error : Self intersecting surface mesh,
> computing intersections (this could take a while)
>
> Hi Matthias,
>
> I think you are talking about your mail from 12.03.2014 09:59 ?
> In one of my last mails I already sent you a selfcreated .msh file -
> but the 3D mesh still failes. The intersect.pos shows me some
>
> intersections, but when I check my nodes for duplicates I can't find any.
> Hope my steps are correct:
> - create "my_file.msh" with my python script and check it for nodes
> duplications -> none found
> - open "my_file.geo" in Gmsh
> - do "Modules" -> "Mesh" -> "3D"
> - receive error message
> - merge "intersect.pos" and see some intersections but I don't know
> why because the are no duplicated nodes
>
> Steffen
>
>
> Am 14.03.2014 09:50, schrieb Zenker, Dr. Matthias:
>
> Hi Steffen,
>
> you should be able to generate a filled volume mesh if you follow
> my suggestion from the other mail:
>
> Write the 2D mesh in gmsh format (e.g. as outerface.msh, gmsh
> documentation for more info on the msh format) and merge that one
> instead of the myfile.ply2 file, leaving the other command lines
> in your .geo file as they are. If you then do a 3D mesh, gmsh will
> take the 2D mesh as defined in your file. You can then refine the
> mesh if you wish.
>
> HTH,
>
> Matthias
>
> *Von:*Steffen Becker [mailto:steffenbecker87 at yahoo.de]
> *Gesendet:* Mittwoch, 12. März 2014 20:00
> *An:* Roman Fratczak
> *Cc:* Zenker, Dr. Matthias; gmsh at geuz.org <mailto:gmsh at geuz.org>
> *Betreff:* Re: [Gmsh] Error : Self intersecting surface mesh,
> computing intersections (this could take a while)
>
> Hi,
>
> I'm so sorry for all time you spent with my problem, but now I
> see: We talk at cross. It's my fault, I didn't explained correctly
> what I need.
> I want to receive a *filled* volume mesh.
> I created 2 files (steffen.stl and steffen2.stl) with my python
> script.
> With steffen.stl I successfully could create such a filled volume
> mesh as seen in steffen.msh.
> When I try exactly the same with steffen2.stl then I get the error
> message in the subject (and the surface mesh doesn't get filled).
> So that's why the .iges file you sent me isn't what I need.
>
> Sorry for all this confusion,
> Steffen
>
>
> Am 12.03.2014 18:53, schrieb Roman Fratczak:
>
> Steffen,
>
> I did a volume based on your surface mesh - see attached IGES
> (compressed with 7-zip).
> After reading it into GMSH, you can create the 1D, then 2D and
> finally 3D mesh with no errors.
>
> You can do the same using GMSH volume definition (as already
> wrote)-> it will work, as the fundamental faces are plane
> triangles.
>
> Regards
> Roman
>
>
> W dniu 12.03.2014 18:27, Steffen Becker pisze:
>
> Wrong .geo file, sorry!
>
> Am 12.03.2014 18:21, schrieb Steffen Becker:
>
> Thank you so far,
>
> I create both files: .msh and .geo, but I still get
> the same error. What's my mistake?
>
> Steffen
>
> Am 12.03.2014 11:48, schrieb Roman Fratczak:
>
> Hi,
>
> FYI - you can remove double vertices/edges (or
> repair) in mesh in FreeCad (for exampe).
>
> regards
> Roman
>
>
>
> W dniu 12.03.2014 10:17, Steffen Becker pisze:
>
> Hi Matthias & Roman,
>
> I create a nodes- and elements-list like this:
> # nodes:
> N1 0,0,0
> N2 0,1,0
> N3 1,0,0
> N4 0,0,1
> # elements, which describe triangles:
> E1 1,2,3
> E2 2,3,4
>
> So I do have double edges (here: between node
> 2+3). Didn't now that this is a problem for
> gmsh, sorry.
>
> I will try Romans solution asap and give you a
> feedback.
> Thank you both!
>
> Steffen
>
>
> Am 12.03.2014 09:59, schrieb Zenker, Dr. Matthias:
>
> Hi Steffen,
>
> I am not totally sure from what you wrote
> that there are really no duplicated nodes.
> In gmsh, you need to define the surfaces
> in a way that neighbouring surfaces/facets
> with a common border use the _/same/_
> nodes to define the border. I could not
> see from your file if there are duplicated
> nodes, and would propose that you make
> sure that there are really no such
> duplications.
>
> If the meshing still fails, then this is a
> question for the real gurus (Christophe?).
>
> HTH,
>
> Matthias
>
> *Von:*Roman Fratczak
> [mailto:fratczakroman at o2.pl]
> *Gesendet:*Mittwoch, 12. März 2014 09:51
> *An:* Steffen Becker
> *Cc:* gmsh at geuz.org <mailto:gmsh at geuz.org>
> *Betreff:* Re: [Gmsh] Error : Self
> intersecting surface mesh, computing
> intersections (this could take a while)
>
> Hi Steffen,
>
> No it is more clear. If you are working
> with cloud of point, then you may use
> Meshlab for surface regeneration. There
> are many software that are able to handle
> in a resonable way the cloud of points
> (like rhino3D + resurf, other). But these
> are rather commercial.
>
> From the other side - try to do the
> simplest thing:
>
> Adjust your python script for surface
> creation in order to save not as PLY but
> as GMSH "geo" file using points and lines
>
> Point(1)={0,0,0} ;
> Point(2)={0,1,0} ;
> ...
>
> Line(1) = {1,2};
> ..
> and.. Line Loop & Surface -> Volume ..
>
> Then you will get a volume defined by
> geometric entities. In this case is shoul
> be easier to create a better mesh on
> surface and then on whole volume.
>
> Regards
> Roman
>
>
>
> W dniu 11.03.2014 17:59, Steffen Becker pisze:
>
> Hi,
>
> @ Roman:
> some more details:
> I have a point cloud given and
> generate the surface mesh by myself
> (with python). I don't know a good
> algorithm to create a volume mesh out
> of this surface mesh - that's why I
> use gmsh for this task.
> I also checked my surface mesh for
> double vertexes but I didn't find any.
> What do you mean with "double egdes"?
> Isn't there always a "double edge",
> because two neighbour facets always
> have one same edge?!
>
> I will send you a .step or .iges file
> as soon as I figured out how to handle
> the "No OpenCASCADE model found" error.
>
> I'm appending the other mailing
> history (with Matthias) to this mail -
> sorry for that "double mailing", I
> just forgot one time to "reply to all" -.-
> Anyone else has an idea why the
> meshing fails?
>
> Regards and thank you a lot,
> Steffen
>
>
>
>
>
> Hi Steffen,
>
>
>
> I don't see either why the meshing fails, sorry.
>
>
>
> Matthias
>
>
>
> -----Ursprüngliche Nachricht-----
>
> Von: Steffen Becker [mailto:steffenbecker87 at yahoo.de]
>
> Gesendet: Dienstag, 11. März 2014 14:42
>
> An: Zenker, Dr. Matthias
>
> Cc:gmsh at geuz.org <mailto:gmsh at geuz.org>
>
> Betreff: Re: [Gmsh] Error : Self intersecting surface mesh, computing
>
> intersections (this could take a while)
>
>
>
> Oh I'm really sorry, here is the file.
>
> In addition I sent you also the intersect.pos. I don't understand why exactly
>
> these surfaces are problematic and the "neighbour surfaces"
>
> aren't - although they have the same geometry =/
>
>
>
> Am 11.03.2014 12:07, schrieb Zenker, Dr. Matthias:
>
> Hi Steffen,
>
>
>
> if you don't provide the myfile.ply2, we cannot see your geometry...
>
> You can visualize intersect.pos by merging it to your geometry.
>
>
>
> HTH,
>
>
>
> Matthias
>
>
>
>
>
> Am 11.03.2014 14:33, schrieb Roman
> Fratczak:
>
> Hello,
>
> It is possible, that you will get
> your geometry in other format?
> In your "ply" there is already a
> surface mesh given. Try maybe use
> STEP, IGES,... as input- then it
> is easer to recalculate the
> surface mesh.
>
> In case of need of usage of "a
> dead mesh" - maybe try first to
> remesh it (i.e. in blender with
> modification Remesh) and/or clean
> it (removing double vertexes and
> edges).
>
> regards
> Roman
>
>
>
>
> W dniu 11.03.2014 12:13, Steffen
> Becker pisze:
>
> Hi,
>
> in the appendix you find my model.
> Thanks for help!!
>
> Regards,
> Steffen
>
> Am 11.03.2014 11:47, schrieb
> Roman Fratczak:
>
> Hello Steffen,
>
> Yes. You can try to the
> first Optimize quality of
> tetra, or all of them
> (just try).
>
> I don't know how your
> model looks like. If the
> elements on the surface
> are too big, then the
> solid elements (probably
> tetragonal) may be with
> intersecting edges or
> faces. Therefore the
> reducing size of element
> may help (especially on
> the surfaces).
>
> Or- just share your model
> (ply) -in order to be more
> precise.
>
> regards
> Roman
>
>
>
> W dniu 10.03.2014 18:06,
> Steffen Becker pisze:
>
> Hi Roman,
> when you say "enable
> option: optimize", you
> mean" Tools -> Options
> -> Mesh -> Advanced ->
> Optimize quality of
> tetrahedra, Optimize
> quality of tetrahedra
> with Netgen, Optimize
> high order meshes
> (experimental)" ?
> And why is reducing
> element size
> important? In my case
> it is important that
> the object has such
> "90 degree corners".
>
> Regards,
> Steffen
>
> Am 10.03.2014 16:55,
> schrieb Roman Fratczak:
>
> Hi Steffen,
>
> If your volume is
> OK (is really a
> closed one) - try to:
>
> 1. Reduce element
> size (especially
> in a curved shapes)
> 2. Enable option
> "Optimize" - in
> mesh options
>
> Regards
> Roman
>
>
>
> W dniu 10.03.2014
> 16:41, Steffen
> Becker pisze:
>
> Hello everyone,
>
> I'm a gmsh
> beginner and I
> want to create
> a 3D volume
> mesh out of a
> given
> surface-mesh
> but I got the
> error message
> as seen in the
> subject. You
> find my .geo
> file in the
> appendix.
> Can anyone
> tell me what I
> have to do to
> create a 3D
> mesh? I even
> can't figure
> out where the
> intersection
> are located
> (don't know
> how to read
> the
> intersect.pos).
> Sorry for my
> poor english.
>
> Regards,
> Steffen
>
>
>
>
>
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> _____________________________________________________________________
> ERBE Elektromedizin GmbH
> Firmensitz: 72072 Tuebingen
> Geschaeftsfuehrer: Christian O. Erbe, Reiner Thede
> Registergericht: Stuttgart HRB 380137
>
>
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> _____________________________________________________________________
> ERBE Elektromedizin GmbH
> Firmensitz: 72072 Tuebingen
> Geschaeftsfuehrer: Christian O. Erbe, Reiner Thede
> Registergericht: Stuttgart HRB 380137
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