Issues with VTK TENSORS6

ParaView Support
1

  • We are told that VTK/Legacy is deprecated, but what would be an alternative for someone who does not have much time to figure out how to create a dataset from say Matlab)= for his own finite element code)?

  • I am baffled by an error I get when trying to define a tensor (Error reading ascii data. Possible mismatch of datasize with declaration.)

’

# vtk DataFile Version 3.0
Increment No. 2 
ASCII
DATASET UNSTRUCTURED_GRID
POINTS  12 float
0.000000e+00 0.000000e+00 0.000000e+00
1.000000e+00 0.000000e+00 0.000000e+00
1.000000e+00 1.000000e+00 0.000000e+00
0.000000e+00 1.000000e+00 0.000000e+00
0.000000e+00 0.000000e+00 2.000000e+00
1.000000e+00 0.000000e+00 2.000000e+00
1.000000e+00 1.000000e+00 2.000000e+00
0.000000e+00 1.000000e+00 2.000000e+00
0.000000e+00 0.000000e+00 1.000000e+00
1.000000e+00 0.000000e+00 1.000000e+00
1.000000e+00 1.000000e+00 1.000000e+00
0.000000e+00 1.000000e+00 1.000000e+00
CELLS 2 18
     8     5     6     9    10     4     7     8    11
     8     9    10     1     2     8    11     0     3
CELL_TYPES 2
    11
    11
CELL_DATA      2
SCALARS CELL_SCALARS INT 1
LOOKUP_TABLE default
1
7
POINT_DATA   12
TENSORS6 Cauchy_Stress float
LOOKUP_TABLE default
3.132000e+00 3.327000e-16 3.296000e-01 
3.327000e-16 3.132000e+00 3.296000e-01 
3.296000e-01 3.296000e-01 2.044000e+01 
3.132000e+00 5.132000e-16 -3.296000e-01 
4.132000e-16 3.132000e+00 3.296000e-01 
-3.296000e-01 3.296000e-01 2.044000e+01 
3.132000e+00 8.566000e-17 -3.296000e-01 
8.566000e-17 3.132000e+00 -3.296000e-01 
-3.296000e-01 -3.296000e-01 2.044000e+01 
3.132000e+00 -4.398000e-18 3.296000e-01 
-4.398000e-18 3.132000e+00 -3.296000e-01 
3.296000e-01 -3.296000e-01 2.044000e+01 
-6.991000e-02 -4.694000e-17 -6.991000e-02 
-4.694000e-17 -6.991000e-02 -6.991000e-02 
-6.991000e-02 -6.991000e-02 2.009000e+01 
-6.991000e-02 -2.851000e-16 6.991000e-02 
-2.851000e-16 -6.991000e-02 -6.991000e-02 
6.991000e-02 -6.991000e-02 2.009000e+01 
-6.991000e-02 -8.146000e-16 6.991000e-02 
-8.146000e-16 -6.991000e-02 6.991000e-02 
6.991000e-02 6.991000e-02 2.009000e+01 
-6.991000e-02 -5.687000e-16 -6.991000e-02 
-5.687000e-16 -6.991000e-02 6.991000e-02 
-6.991000e-02 6.991000e-02 2.009000e+01 
1.997000e-01 5.649000e-16 1.298000e-01 
5.649000e-16 1.997000e-01 1.298000e-01 
1.298000e-01 1.298000e-01 1.973000e+01 
1.997000e-01 6.355000e-16 -1.298000e-01 
6.355000e-16 1.997000e-01 1.298000e-01 
-1.298000e-01 1.298000e-01 1.973000e+01 
1.997000e-01 -9.796000e-17 -1.298000e-01 
-9.796000e-17 1.997000e-01 -1.298000e-01 
-1.298000e-01 -1.298000e-01 1.973000e+01 
1.997000e-01 -1.632000e-16 1.298000e-01 
-1.632000e-16 1.997000e-01 -1.298000e-01 
1.298000e-01 -1.298000e-01 1.973000e+01
2

VTK format is legacy, not deprecated.

XML VTK format is the alternative.

All information are here:
https://vtk.org/wp-content/uploads/2015/04/file-formats.pdf

3

Thanks, VTK I get it (despite a lingering error in defining TENSORS6), but the “legacy” adjective is somehow ominous and as such have been looking at VTU. However I could not find a documentation on how to write the VTU file.

Having said that where would i find documentation on how to write (from Matlab) an XML VTK file (btw is this the same as VTU)?

thanks

victor

4

The documentation is in the link I provided.

.vtk and .vtu are not the same at all, the first is the legacy format you know, .vtu is the XML based format to store unstructured grid.

5

Oops sorry, you are right, but is there an advantage of using VTU/XML format over the vtk one?

And may I please ask your input on the TENSOR6 issue I am having (might be something simple/obvious, but I just do not get it).

thanks

6

Yes, the XML format are much more flexible et generally faster.

No idea about your tensor issue. Here is an example of a tensor file in .vtk format that is working perfectly. symTensor.vtk (925 Bytes)