Thank you a lot!
I couldn't yet find out why/where I create those ill-defined triangles,
but that's not you problem ;-P
I have one last question:
Can you tell me in a short, easy way the algorithm how Gmsh creates new
nodes inside the given surface-mesh?
Regards,
Steffen
Am 19.03.2014 09:15, schrieb Zenker, Dr. Matthias:
>
> Hi Steffen,
>
> the difference between 0 and 0.0000000001 might be a rounding error.
>
> Now if you have holes in your surface if you just delete all
> ill-defined triangles, I don't know. It depends on how you made your
> triangulation. IMO it would be better to make sure that such triangles
> are not even be created.
>
> Matthias
>
> *Von:*Steffen Becker [mailto:steffenbecker87 at yahoo.de]
> *Gesendet:* Dienstag, 18. März 2014 21:47
> *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)
>
> What I just think about:
> I just deleted all the lines in my elements-list where area is <=
> 0.000000001. Doesn't that mean that I have small holes in my surface
> mesh now? How is Gmsh able to work with this? I just don't understand
> why this makes a difference compared to just check if area is = 0
>
> Steffen
>
> Am 18.03.2014 21:41, schrieb Steffen Becker:
>
> Hi,
> puh, that's weird:
> First I checked my triangles if their area is > 0 (to get the ones
> which are aligned). This didn't helped as I said in my last mail.
> Now I (just for fun) checked if the area > 0.000000001 and now it
> works - but I don't know why this is such a difference?!
>
> Anyway, thanks for your help!
> Steffen
>
> Am 18.03.2014 10:57, schrieb Zenker, Dr. Matthias:
>
> Hi Steffen,
>
> there are still ill-defined triangles, e.g. 2319, 2320, 2321.
> You can find that out by yourself by inspecting your mesh with
> gmsh in the way I described in my last mail.
>
> Remark: checking "surface faces" can help to examine the surface.
>
> HTH,
>
> Matthias
>
> *Von:*Steffen Becker [mailto:steffenbecker87 at yahoo.de]
> *Gesendet:* Montag, 17. März 2014 22:39
> *An:* Zenker, Dr. Matthias
> *Cc:* Roman Fratczak; 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 Matthias,
>
> thank you for your help!
> I think I successfully deleted all the triangles with zero
> surface. Unfortunately the same error still appears (but at
> least with much less intersections). You find my new .msh file
> in the appendix. Do you have more ideas?
>
> Regards,
> Steffen
>
> Am 17.03.2014 11:37, schrieb Zenker, Dr. Matthias:
>
> Hi Steffen,
>
> I think you have ill-defined triangles in your mesh. For
> example, there is a triangle 15328 which contains the
> nodes 7358, 7359, and 7360. But these nodes are aligned,
> so the triangle has zero surface. I would suspect this
> kind of problem to be the cause for the failure. I
> discovered that by examining your mesh after merging the
> intersect.pos, and by displaying node labels and surface
> labels in gmsh. I saw that this triangle was not visible,
> just its label, and searched for "15328" in your msh file
> to see what nodes it contains.
>
> You should make sure that this kind of thing cannot happen
> when you define the surface mesh.
>
> HTH,
>
> Matthias
>
> *Von:*Steffen Becker [mailto:steffenbecker87 at yahoo.de]
> *Gesendet:* Montag, 17. März 2014 11:20
> *An:* Zenker, Dr. Matthias
> *Cc:* Roman Fratczak; gmsh at geuz.org <mailto:gmsh at geuz.org>
> *Betreff:* Re: [Gmsh] Error : Self intersecting surface
> mesh, computing intersections (this could take a while)
>
> Here it is.
>
> Am 17.03.2014 11:14, schrieb Zenker, Dr. Matthias:
>
> Hi Steffen,
>
> I found out: Outlook is wrong.
>
> I just discovered a small info saying that Outlook
> thinks that my_file.msh is insecure and that it has
> deleted the attachment (Grrrr). So the fault was on my
> side, sorry. Could you try to send it again with a
> changed extension, e.g. rename it to my_file.msh.txt?
>
> Matthias
>
> *Von:*Steffen Becker [mailto:steffenbecker87 at yahoo.de]
> *Gesendet:* Montag, 17. März 2014 10:55
> *An:* Zenker, Dr. Matthias
> *Cc:* Roman Fratczak; 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 Matthias,
>
> I don't know what's wrong here.
> When I check my mails, there is a .msh file in the
> mail from 12.03.2014 18:21 and also one in the mail
> from 14.03.2014 12:33.
> Finally, I sent you again a .msh file in this mail. Do
> you receive it?
>
> Steffen
>
>
> Am 17.03.2014 09:52, schrieb Zenker, Dr. Matthias:
>
> Hi Steffen,
>
> in the mail you mention there is only a geo file...
>
> Matthias
>
> *Von:*Steffen Becker
> [mailto:steffenbecker87 at yahoo.de]
> *Gesendet:* Freitag, 14. März 2014 21:09
> *An:* Zenker, Dr. Matthias
> *Cc:* Roman Fratczak; 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 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
> <mailto: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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>
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>
>
>
>
>
>
>
>
>
>
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>
>
>
>
>
>
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>
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> _____________________________________________________________________
> ERBE
> Elektromedizin GmbH
> Firmensitz: 72072
> Tuebingen
> Geschaeftsfuehrer:
> Christian O. Erbe,
> Reiner Thede
> Registergericht:
> Stuttgart HRB 380137
>
>
>
> _____________________________________________________________________
> ERBE Elektromedizin GmbH
> Firmensitz: 72072 Tuebingen
> Geschaeftsfuehrer: Christian O. Erbe,
> Reiner Thede
> Registergericht: Stuttgart HRB 380137
>
>
>
> _____________________________________________________________________
> ERBE Elektromedizin GmbH
> Firmensitz: 72072 Tuebingen
> Geschaeftsfuehrer: Christian O. Erbe, Reiner Thede
> Registergericht: Stuttgart HRB 380137
>
>
>
> _____________________________________________________________________
> ERBE Elektromedizin GmbH
> Firmensitz: 72072 Tuebingen
> Geschaeftsfuehrer: Christian O. Erbe, Reiner Thede
> Registergericht: Stuttgart HRB 380137
>
>
>
> _____________________________________________________________________
> ERBE Elektromedizin GmbH
> Firmensitz: 72072 Tuebingen
> Geschaeftsfuehrer: Christian O. Erbe, Reiner Thede
> Registergericht: Stuttgart HRB 380137
>
>
>
> _____________________________________________________________________
> ERBE Elektromedizin GmbH
> Firmensitz: 72072 Tuebingen
> Geschaeftsfuehrer: Christian O. Erbe, Reiner Thede
> Registergericht: Stuttgart HRB 380137
>
>
>
> _____________________________________________________________________
> ERBE Elektromedizin GmbH
> Firmensitz: 72072 Tuebingen
> Geschaeftsfuehrer: Christian O. Erbe, Reiner Thede
> Registergericht: Stuttgart HRB 380137
>
>
>
> _____________________________________________________________________
> ERBE Elektromedizin GmbH
> Firmensitz: 72072 Tuebingen
> Geschaeftsfuehrer: Christian O. Erbe, Reiner Thede
> Registergericht: Stuttgart HRB 380137
>
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