Contour error in pyvista


when trying contour data after compute_derivative I get an empty dataset even if the value is in the dataset itself.

soln is correctly populated with the various arrays but the contour filter is failing no matter which value I try to get an isosurface of.

soln = pv.get_reader(filename).read() 
soln = soln.compute_derivative(scalars="velocity", qcriterion=True, gradient=False, faster=True, preference="point") 
qcontour = soln.contour(np.array([100]), scalars="qcriterion")

The issue seems to lay in faster flag, when set to False it works as expected.

How can I try to troubleshoot this?

Best regards

Hi @Frankx9, you will likely have better luck getting help over at the PyVista support page. PyVista and ParaView are both related to VTK, but ParaView they are separate projects.

Hi @cory.quammen,

I’ve asked them as well but checking their source code there is nothing strange on their side, they’re calling

alg = _vtk.vtkContourFilter()

but when the input array is processed with :

alg = _vtk.vtkGradientFilter()

the contour fails if faster approximation is required

Do you have any further insight on vtk side?

Best regards