[vtkusers] Large performance difference between vtkResampleWithDataSet in VTK 8.1.0 and Resample with Dataset filter in Paraview 5.5

[Evan Kao]

Hello all,

I am trying to resample a structured grid data (~1.4M points, 1.3M cells)
with an unstructured grid (~320K points, 480K cells).  In Paraview 5.5,
this resampling is nearly instant with the Resample With Dataset filter.
Yet in a Python script using vtkResampleWithDataSet from VTK 8.1.0, the
same operation takes about 15 minutes (>2 orders of magnitude difference in
speed).  As far as I can tell from the VTK repository on Gitlab, the only
difference between the Paraview/release version and the 8.1.0 or 8.1.1
tagged releases is a switch in the cell locator.  Is this enough to explain
the difference in the performance?  If not, could someone enlighten me as
to what the possible factors are here?

Also, if it matters, this is all on a Windows 7 64-bit machine.  Paraview
is installed from binaries, while VTK was downloaded from an Anaconda
distribution compiled by a third party.

Thanks for your time,
Evan Kao
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