Merging simulation data from vtk and vtu files

ParaView Support
1

I would like to merge two simulation data sets, one based on a structured and one on an unstructured mesh together and validate my model against another one by computing absolute value differences of certain quantities.

I saw that some people ran into the same issues after grouping, getting an appendix (Partial) to all their scalar fields and not being able to compute a new scalar field computed from both, quantities of dataset 1 and 2. They were advised to try the AppendAttributes filter.

I did all that. Still, after applying the AppendAttributes filter, the quantities are still (partial). And I can plot quantities of either dataset 1 or 2, but as soon as I use the calculator to computer something like abs(q1-q2) I always get “Syntax error: Operator expected;” and the calculator result gets appended by (?).

If I understand it correctly, I do not have to interpolate both datasets onto a single mesh as this is done implicitly. Am I wrong about that? Or is it maybe not possible to combine data from structured/unstructured meshes?

Thanks a lot for your help!

2

AppendAttributes would only make sense if both your inputs have the same number of cells and points.

If that is not the case, you want to use ResampleWithDataset.

1 Like
3

Thank you for that information.

When I apply the filter ResampleWithDatasets, I am asked to specify either a source or an input - but only one, I cannot select both sources/inputs. I tried applying the filter on the already grouped together datasets and also tried to apply it on dataset 1 and specify dataset 2 as a source/input in the filter. But both approaches don’t work. I get an error ‘Algorithm vtkPResampleWithDataSet(0x14feb7ba0) returned failure for request’.

4

Steps:

  • Click on the dataset containing data arrays you want to resample
  • Add a ResampleWithDataSet filter
  • In the input window, click on the “Destination Mesh” radio box
  • In the input window, click on the dataset you want to use the geometry as output
  • Click on OK
  • Check PassPointData and PassCellData arrays,
  • Apply
1 Like
5

Thank you so much for your reply!

I just realized, on our cluster an older Paraview 5.6 version is installed, why I couldn’t find the “Destination Mesh” radio box nor the PassPointData and PassCellData options. Repeating your steps with “Source” instead of “Destination Mesh” in Paraview 5.6 still results in an error once I use the calculator after sampling and subsequent grouping: “Syntax error: expecting a variable name.”

So I will try this again with Paraview 5.8. Thanks again.

6

Indeed, the naming were changed a few months ago to avoid confusion. Let me know.