[Gmsh] mesh problem
stefano zinna
stefano.zinna at uniheat.it
Fri Dec 18 23:57:35 CET 2009
Dear Dave.
I cleaned the iges file
(https://download.yousendit.com/Z01PcXlsaTFTSUNGa1E9PQ) and generate a
surface mesh(https://download.yousendit.com/Z01PcXlnaFJ6RS9IRGc9PQ). The
mesh has some problem because there are some intersected surfaces that
you can see in the mesh.
This is due to the geometry tolerance. What do you think? How can i
solve this problem?
thanks again for your kind reply.
Stefano
David Colignon wrote:
> If you just open your step file with Gmsh, you can see that there are
> some warnings and some errors:
>
> ...
> ...
> Info : removing degenerated edge 0
> Info : removing degenerated edge 0
> Info : - fixing wire gaps
> Info : some 2D gaps fixed
> Info : some 3D gaps fixed
> Info : failed to fix some 2D gaps
> Info : failed to fix some 3D gaps
> Info : - fixing spot and strip faces
> Warning : OCC STL triangulation failed
> Error : Something wrong in edge loop
> Error : Something wrong in edge loop
> Error : Something wrong in edge loop
> Error : Something wrong in edge loop
> Warning : OCC STL triangulation failed
> Error : Something wrong in edge loop
> Error : Something wrong in edge loop
> Error : Something wrong in edge loop
> Error : Something wrong in edge loop
> Error : Something wrong in edge loop
> Error : Something wrong in edge loop
> Error : Something wrong in edge loop
> Error : Something wrong in edge loop
> Error : Something wrong in edge loop
> Error : Something wrong in edge loop
> Error : Something wrong in edge loop
> Error : Something wrong in edge loop
> Error : Something wrong in edge loop
> Error : Something wrong in edge loop
> Error : Something wrong in edge loop
> Error : Something wrong in edge loop
> Error : Something wrong in edge loop
> Error : Something wrong in edge loop
> Error : Something wrong in edge loop
> Error : Something wrong in edge loop
> Error : Something wrong in edge loop
> Error : Something wrong in edge loop
> Error : Something wrong in edge loop
> Error : Something wrong in edge loop
> Error : Something wrong in edge loop
> Error : Something wrong in edge loop
> Error : Something wrong in edge loop
> Error : Something wrong in edge loop
> Error : Something wrong in edge loop
> Info : OCC Region 1 - New Shell
> Info : OCC Region 1 with 2001 faces
> Info : Read '/Users/colignon/Desktop/newfile.stp'
>
>
> but they are perhaps not "blocking".
> In Tools -> Options -> Geometry -> General , Gmsh has some *basic* and
> *experimental* reparation features. You can increase the Tolerance, ...
> But you should check and clean your geometry in your CAD software. For
> example, with Tools -> Visibility, and by displaying the surfaces with
> "ALT+s" you can see that for some reason Gmsh cannot display properly
> surface 903
>
> If you use the command line to try to mesh your geometry in 2D, you
> will get much more messages which could help you to find the problems
> in your geometry (note that Gmsh crashes before the end)
>
> ace35:~/Desktop > gmsh newfile.stp -2
>
> Info : Running '/Applications/Gmsh.app/Contents/Resources/bin/gmsh
> newfile.stp -2'
> Info : Started on Fri Dec 18 10:32:01 2009
> Info : Reading 'newfile.stp'
> *** Error on Record 4039 (on 440531 -> 0 % in File) *** Ident #2022
> Complex Type incorrect : SOLID_ANGLE_UNIT / SI_UNIT ...
> *** Error on Record 27742 (on 440531 -> 6 % in File) *** Ident #9776
> Complex Type incorrect : RATIONAL_B_SPLINE_SURFACE / BOUNDED_SURFACE ...
> *** Error on Record 27744 (on 440531 -> 6 % in File) *** Ident #9776
> Complex Type incorrect : REPRESENTATION_ITEM /
> GEOMETRIC_REPRESENTATION_ITEM ...
> *** Error on Record 37721 (on 440531 -> 8 % in File) *** Ident
> #12125
> Complex Type incorrect : NAMED_UNIT / LENGTH_UNIT ...
> *** Error on Record 340757 (on 440531 -> 77 % in File) *** Ident
> #171717
> Complex Type incorrect : RATIONAL_B_SPLINE_CURVE / BOUNDED_CURVE ...
> *** Error on Record 340759 (on 440531 -> 77 % in File) *** Ident
> #171717
> Complex Type incorrect : REPRESENTATION_ITEM /
> GEOMETRIC_REPRESENTATION_ITEM ...
> *** Error on Record 340760 (on 440531 -> 77 % in File) *** Ident
> #171717
> Complex Type incorrect : GEOMETRIC_REPRESENTATION_ITEM / CURVE ...
> *** Error on Record 341398 (on 440531 -> 77 % in File) *** Ident
> #172039
> Complex Type incorrect : RATIONAL_B_SPLINE_CURVE / BOUNDED_CURVE ...
> *** Error on Record 341400 (on 440531 -> 77 % in File) *** Ident
> #172039
> Complex Type incorrect : REPRESENTATION_ITEM /
> GEOMETRIC_REPRESENTATION_ITEM ...
> *** Error on Record 341401 (on 440531 -> 77 % in File) *** Ident
> #172039
> Complex Type incorrect : GEOMETRIC_REPRESENTATION_ITEM / CURVE ...
> *** Error on Record 348024 (on 440531 -> 79 % in File) *** Ident
> #174944
> Complex Type incorrect : RATIONAL_B_SPLINE_CURVE / BOUNDED_CURVE ...
> *** Error on Record 348026 (on 440531 -> 79 % in File) *** Ident
> #174944
> Complex Type incorrect : REPRESENTATION_ITEM /
> GEOMETRIC_REPRESENTATION_ITEM ...
> *** Error on Record 348027 (on 440531 -> 79 % in File) *** Ident
> #174944
> Complex Type incorrect : GEOMETRIC_REPRESENTATION_ITEM / CURVE ...
> *** Error on Record 349696 (on 440531 -> 79 % in File) *** Ident
> #175652
> Complex Type incorrect : RATIONAL_B_SPLINE_CURVE / BOUNDED_CURVE ...
> *** Error on Record 349698 (on 440531 -> 79 % in File) *** Ident
> #175652
> Complex Type incorrect : REPRESENTATION_ITEM /
> GEOMETRIC_REPRESENTATION_ITEM ...
> *** Error on Record 349699 (on 440531 -> 79 % in File) *** Ident
> #175652
> Complex Type incorrect : GEOMETRIC_REPRESENTATION_ITEM / CURVE ...
> Info : Healing geometry (tolerance=1e-06)
> Info : - fixing small edges
> Info : removing degenerated edge 0
> ...
> ...
> Info : removing degenerated edge 0
> Info : - fixing wire gaps
> Info : some 2D gaps fixed
> Info : some 3D gaps fixed
> Info : failed to fix some 2D gaps
> Info : failed to fix some 3D gaps
> Info : - fixing spot and strip faces
> Error : Something wrong in edge loop
> Error : Something wrong in edge loop
> ...
> ...
> Error : Something wrong in edge loop
> Info : OCC Region 1 - New Shell
> Info : OCC Region 1 with 2001 faces
> Info : Read 'newfile.stp'
> Info : Meshing 1D...
> Info : Meshing curve 1 (BSpline)
> ...
> ...
> ...
> Info : Meshing curve 603 (BSpline)
>
> Info : Meshing curve 604 (Unknown)
>
> Info : Meshing curve 605 (BSpline)
>
> Info : Meshing curve 725 (Unknown)
>
> Info : Meshing curve 741 (Unknown)
>
> Info : Meshing curve 760 (Unknown)
> Info : Meshing surface 100 (BSpline surface, MeshAdapt)
> Info : Meshing surface 101 (Unknown, MeshAdapt)
> Info : Meshing surface 102 (Unknown, MeshAdapt)
> Info : Meshing surface 103 (Unknown, MeshAdapt)
> Info : Meshing surface 104 (BSpline surface, MeshAdapt)
> Warning : :-( There are 6 intersections in the 1D mesh (curves 501 448
> 495 502 447 454)
> Warning : 8-| Gmsh splits those edges and tries again
> Warning : :-( There are 2 intersections in the 1D mesh (curves 447 454)
> Warning : 8-| Gmsh splits those edges and tries again
> Warning : :-) Gmsh was able to recover all edges after 2 iterations
> Info : Meshing surface 105 (Plane, MeshAdapt)
>
> Info : Meshing surface 210 (BSpline surface, MeshAdapt)
> Warning : :-( There are 3 intersections in the 1D mesh (curves 890 892
> 894)
> Warning : 8-| Gmsh splits those edges and tries again
> Warning : :-( There are 3 intersections in the 1D mesh (curves 890 894
> 892)
> Warning : 8-| Gmsh splits those edges and tries again
> Warning : :-( There are 3 intersections in the 1D mesh (curves 890 892
> 894)
> Warning : 8-| Gmsh splits those edges and tries again
> Warning : :-( There are 2 intersections in the 1D mesh (curves 892 890)
> Warning : 8-| Gmsh splits those edges and tries again
> Warning : :-) Gmsh was able to recover all edges after 4 iterations
> Info : Meshing surface 211 (BSpline surface, MeshAdapt)
>
> Info : Meshing surface 274 (Plane, MeshAdapt)
> Warning : :-( There are 6 intersections in the 1D mesh (curves 1195
> 1195 1196 1196 1181 1182)
> Warning : 8-| Gmsh splits those edges and tries again
> Info : Meshing surface 275 (BSpline surface, MeshAdapt)
>
> Info : Meshing surface 336 (BSpline surface, MeshAdapt)
> Warning : :-( There are 3 intersections in the 1D mesh (curves 1428
> 1429 1438)
> Warning : 8-| Gmsh splits those edges and tries again
> Warning : :-( There are 3 intersections in the 1D mesh (curves 1429
> 1429 1437)
> Warning : 8-| Gmsh splits those edges and tries again
> Warning : :-) Gmsh was able to recover all edges after 2 iterations
> Info : Meshing surface 337 (BSpline surface, MeshAdapt)
>
> Info : Meshing surface 348 (Plane, MeshAdapt)
> Warning : :-( There are 5 intersections in the 1D mesh (curves 1213
> 1216 1216 1479 1479)
> Warning : 8-| Gmsh splits those edges and tries again
> Info : Meshing surface 349 (BSpline surface, MeshAdapt)
>
>
> Dave
>
>
>
>
> On 18/12/09 09:52, stefano zinna wrote:
>> Dear David.
>>
>> Thank you for the fast reply. I made a routine to avoid double lines so
>> i think this isn't the problem.
>> I have the original step file
>> (https://download.yousendit.com/Z01PSkhYcVhuSlIzZUE9PQ). Can you explain
>> which steps are better to generate the mesh?
>>
>> kind regards,
>> Stefano
>>
>> David Colignon wrote:
>>>
>>> On 17/12/09 18:36, stefano zinna wrote:
>>>> Dear Sirs.
>>>>
>>>> I converted a .stl file into .geo
>>>> (https://download.yousendit.com/Z01NSU5OOW5samQzZUE9PQ) for gmsh.
>>>
>>> Hi Stefano,
>>>
>>> very nice geometry !
>>>
>>> Are you *sure* that each line shared by two triangles is only defined
>>> once ? (it seems to be the case...)
>>>
>>> I'm
>>>> able to generate the surface mesh but it is not able to recognize the
>>>> volume. Is it a problem in the file or it depends on the complexity of
>>>> the geometry?
>>>
>>>
>>> When you try to create the volume with the GUI and you click on a
>>> first surface, you can see that almost all the surfaces are then
>>> selected and change color to red. But the GUI keep asking to select
>>> volume boundary to fully close the volume. Due to the complexity of
>>> the geometry, it is very difficult to detect with the eye by zooming
>>> on every part of the geometry if some surfaces are missing, so I
>>> cannot see there is a real problem in the geometry or if some surfaces
>>> are left unselected...
>>>
>>> Converting your CAD file to the STL format and then converting it to
>>> .geo is not the best solution. Do you have access to the original CAD
>>> file ? Can you try to export it to the STEP format instead ?
>>>
>>> Regards,
>>>
>>> Dave
>>>
>>
>