[Gmsh] Error : Self intersecting surface mesh, computing intersections (this could take a while)

[Steffen Becker]

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
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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>>>>>> gmsh at geuz.org
>>>>>> http://www.geuz.org/mailman/listinfo/gmsh
>>>>>
>>>>>
>>>>>
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>>>>
>>>>
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>>
>

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