[Paraview] Failed to determine the LookupTable being used

[Cory Quammen]

On Tue, Apr 17, 2018 at 8:52 AM, Sgouros, Thomas <thomas_sgouros at brown.edu>
wrote:

> Hello all:
>
> I have a trace from a simple contour that I drew on a data set, and there
> are parts of it that I don't understand. Here it is, with some question
> numbers:
>
> from paraview.simple import *
>
> data = EnSightReader(CaseFileName='/my/data/file.case')
>
> renderView1 = GetActiveViewOrCreate('RenderView')
> dataDisplay = Show(data, renderView1)    ## 1
>
> dataDisplay.Representation = 'Surface'
> renderView1.ResetCamera()
> dataDisplay.SetScalarBarVisibility(renderView1, True)
> renderView1.Update()
>
> pressureLUT = GetColorTransferFunction('pressure')  ## 2
> contour1 = Contour(Input=data)
>
> contour1.ContourBy = ['POINTS', 'uds_0_scalar']
> contour1.Isosurfaces = [500.0]
>
> contour1Display = Show(contour1, renderView1)
> contour1Display.Representation = 'Surface'
> Hide(data, renderView1)
>
> contour1Display.SetScalarBarVisibility(renderView1, True) ## 3
> renderView1.Update()
>
>
> My questions:
>
>  1. Why do I have to "Show" the raw data right after it's read? I almost
> never actually want to do that. I just want to show the contour. Showing
> and Hiding the raw data seems like a waste of cycles, but when I remove
> references to dataDisplay, I get an error: "Failed to determine the
> LookupTable being used." which seems oddly unrelated to what I did.
>

Show() sets up the representation for the data you have loaded. I suspect
you are getting the LookupTable error message if you retain the "Hide(data,
renderView1)" call because it is expecting to find representation state for
"data" that you have not set up with "Show()" and it cannot find it. Try
removing the "Hide()" and see if you still see the error.


>  2. Where does this value get used? It doesn't seem to me that it is being
> used, but it seems related to the last and the next question:
>

I assume you mean the "dataDisplay" variable. It is not used in your script
directly, but you could set representation properties later on, which is
why the tracing function defines it. Tracing is pretty awesome, but it
doesn't do anything as fancy as analyzing the resulting trace to remove
unused variables, for instance.


>  3. When I choose different scalar values to contour, I often see the
> same "Failed to determine the LookupTable being used." here. There seem to
> be some limitations on what scalars I can use, but what are they and where
> can I read more about these missing lookup tables?
>

See if my answer to 1 solves the problem. If not, do you see this when you
are coloring by the same array as the array for the lookup table? If so,
you should call "contour1.ComputeScalars = 1". This will tell the contour
filter to produce a scalar array corresponding to the array by which you
contoured. It will contain only the isovalues, which is why it is off by
default.

Thanks
Cory


>
> Thank you,
>
>  -Tom
>
>
>
>
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-- 
Cory Quammen
Staff R&D Engineer
Kitware, Inc.
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