**Moderator:** bernd

We would need such a node numbering sheme from FreeCAD (med) to vtk like we did for CalculiX FEM_Mesh_CalculiX

yep, some volumes are not yet supported at all (penta15) and some do not work (penta6, hexa8 and hexa20) . Since we are before the release I deactivated them ATM. Thus FreeCAD should not crash anymore. It will need some further development.

https://github.com/FreeCAD/FreeCAD/pull/1362

https://github.com/FreeCAD/FreeCAD/pull/1362

@HarryvL:bernd wrote: ↑Tue Mar 13, 2018 2:21 pmWe would need such a node numbering sheme from FreeCAD (med) to vtk like we did for CalculiX FEM_Mesh_CalculiX

We need the node assignments for VTK. Best would be some table how to convert from FreeCAD to vtk. Something like this FEM_Mesh_CalculiX Do you know any resource for this.

Shell elements expanded to C3D15 are shown correctly in paraview.

Translation .frd->.vtk done with: https://forum.freecadweb.org/viewtopic. ... &hilit=vtk

Please see source available in this thread (file: "Eksporty.cs")

Translation .frd->.vtk done with: https://forum.freecadweb.org/viewtopic. ... &hilit=vtk

Please see source available in this thread (file: "Eksporty.cs")

Code: Select all

```
.
.
.
// determine main nodes total number
// elements ccx no.5 (15 node wedge) as they are not supported in VTK
// has to be exported as type ccx type 2 (VTK typ 13)
// additional nodes has to be ommited
int nn = 0;
foreach (KeyValuePair<int, tNode> KVP in NodeTab)
if (KVP.Value.IsFirst)
nn++;
// total number of elements
.
.
.
```

does it mean penta15 in frd = penta15 in vtk ?

BTW: I assume conversion from tetra10 in FreeCAD to vtk is wrong, thus we gone get all the black models. see hint of werner https://forum.freecadweb.org/viewtopic. ... 30#p125688

BTW: I assume conversion from tetra10 in FreeCAD to vtk is wrong, thus we gone get all the black models. see hint of werner https://forum.freecadweb.org/viewtopic. ... 30#p125688

I think not.

mamah uses vtk file version 2.0, and there is no 2nd order wedge available, so he uses a 1st order wedge and drops additional nodes

frd elem no 5 -> vtk cell type 13

Meanwhile we are using vtk file version 4.0. I think now there is a 2nd order wedge.

Please see here:

https://www.vtk.org/doc/nightly/html/vt ... ource.html

Code: Select all

```
typedef enum {
// Linear cells
VTK_EMPTY_CELL = 0,
VTK_VERTEX = 1,
VTK_POLY_VERTEX = 2,
VTK_LINE = 3,
VTK_POLY_LINE = 4,
VTK_TRIANGLE = 5,
VTK_TRIANGLE_STRIP = 6,
VTK_POLYGON = 7,
VTK_PIXEL = 8,
VTK_QUAD = 9,
VTK_TETRA = 10,
VTK_VOXEL = 11,
VTK_HEXAHEDRON = 12,
VTK_WEDGE = 13,
VTK_PYRAMID = 14,
VTK_PENTAGONAL_PRISM = 15,
VTK_HEXAGONAL_PRISM = 16,
// Quadratic, isoparametric cells
VTK_QUADRATIC_EDGE = 21,
VTK_QUADRATIC_TRIANGLE = 22,
VTK_QUADRATIC_QUAD = 23,
VTK_QUADRATIC_POLYGON = 36,
VTK_QUADRATIC_TETRA = 24,
VTK_QUADRATIC_HEXAHEDRON = 25,
VTK_QUADRATIC_WEDGE = 26,
VTK_QUADRATIC_PYRAMID = 27,
VTK_BIQUADRATIC_QUAD = 28,
VTK_TRIQUADRATIC_HEXAHEDRON = 29,
VTK_QUADRATIC_LINEAR_QUAD = 30,
VTK_QUADRATIC_LINEAR_WEDGE = 31,
VTK_BIQUADRATIC_QUADRATIC_WEDGE = 32,
VTK_BIQUADRATIC_QUADRATIC_HEXAHEDRON = 33,
VTK_BIQUADRATIC_TRIANGLE = 34,
```

ahh ... found this https://www.vtk.org/data-model/ and https://www.vtk.org/wp-content/uploads/ ... ormats.pdf page 9 and 10, so no quadratic wedge ...

@Bernd, that's where I got my picture for a "VTK WEDGE (=13)" from.

@UR_, yes that's what I proposed - only export the first 6 of the 15 nodes.

@UR_, yes that's what I proposed - only export the first 6 of the 15 nodes.

@ UR_: VTK_BIQUADRATIC_QUADRATIC_WEDGE = 32, indeed seems to indicate the required VTK cell for a 15-noded wedge is implemented, but in Schroeder's book for version 4.0 there is only mention of 14 linear cell types. Perhaps the quadratic cells are still under development?

Check actual vtk user's guide https://www.vtk.org/vtk-users-guide/ directly https://www.kitware.com/products/books/ ... sGuide.pdf around page 481 (legacy formatting starts few pages above). There is quadratic wedge, but when I was implementing this to my optimizer I skipped quadratic wedge, probably I had an old manual. That time I didn't care about node ordering - in the same order I read nodes from inp file I print them to vtk file.bernd wrote: ↑Wed Mar 14, 2018 1:43 amahh ... found this https://www.vtk.org/data-model/ and https://www.vtk.org/wp-content/uploads/ ... ormats.pdf page 9 and 10, so no quadratic wedge ...

I checked it quickly by comparison of https://www.freecadweb.org/wiki/FEM_Mesh_CalculiX and VTK users guid mentioned above. VTK node order is same as in CalculiX but VTK is 0 based, which makes practically no difference.

EDIT: only 1D quadratic element is an exception.