[Gmsh] Intersecting facets, -d switch
=?windows-1252?Q?Jean-Fran=8D=E7ois_Remacle?=
jean-francois.remacle at uclouvain.be
Mon Nov 12 10:52:22 CET 2007
Blacker, Nalini(Contractor) a écrit :
>
> When attempting to create a 3D mesh in a volume defined from a .stl
> surface mesh (fairly coarse, not optimal cell distribution), I receive
> the error below. A few questions:
>
> 1) Are the intersecting faces related to the 'identical verts' warnings?
>
> 2) What is the -d switch and how do I use it? .. I haven't been able
> to find any mention of this anywhere.
>
> 3) Are the facet numbers listed with their geometric definition
> somewhere? My .stl file doesn't seem to have facet numbers, only their
> geometric definitions. I don't really want to count to the 6770th one
> if I can help it!
>
> 4) What are the numbers used to describe the intersecting subfaces?
> Node numbers? Are they recorded in a file somewhere?
>
> Thanks,
> Nalini
>
> [nalini at flightlab ~/gmsh]$ gmsh mrh90-mod5.geo -3
> Info : Increasing process stack size (10240 kB < 16 MB)
> Info : 'gmsh mrh90-mod5.geo -3 ' started on Mon Nov 12 16:04:35 2007
> Info : Reading 'mrh90-mod5.geo'
> Info : Reading 'mrh90-mod12.stl'
> Info : 10542 facets
> Info : Read 'mrh90-mod12.stl'
> Info : Read 'mrh90-mod5.geo'
> Info : Meshing 1D...
> Info : Mesh 1D complete (0 s)
> Info : Mesh
> Info : Meshing 2D...
> Info : Mesh 2D complete (0 s)
> Info : Mesh
> Info : Meshing 3D...
> Info : Meshing volume 3 (Delaunay)
> Constructing Delaunay tetrahedralization.
> Delaunay seconds: 0.68
> Creating surface mesh.
> Warning: Polygon 1 has two identical verts in facet 6770.
> Warning: Polygon 1 has two identical verts in facet 6785.
> Warning: Polygon 1 has two identical verts in facet 6790.
> Warning: Polygon 1 has two identical verts in facet 6797.
> Perturbing vertices.
> Delaunizing segments.
> Constraining facets.
> Error: Invalid PLC.
> Two subfaces (2969, 2968, 5427) and (10977, 12303, 12831)
> are found intersecting each other.
> Hint: Use -d switch to find all intersecting facets.
> terminate called after throwing an instance of 'int'
> Abort
>
>
It seems that your stl file has facets that self intersect. In the case
of a real CAD model,
gmsh can repair the surface mesh and restart the 3D mesh. For a STL, it
is more problematic.
In the nightly version, I have added a more comprehensive error message,
comuting all intersections
and telling all vertices and faces that have such problem.
JFR
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