[Paraview] Failed to determine the LookupTable being used

[Sgouros, Thomas]

Hi Cory:

Thanks for the note. I tried putting in and removing the Hide, but it seems
to have nothing to do with the issue. What does seem relevant is that I get
this error when I ask for a contour that isn't feasible, though I'm not
sure why the error comes where it does. Where can I find functions to use
to interrogate the data set -- data types, variables, and ranges?

Thank you,

 -Tom

On Tue, Apr 17, 2018 at 9:17 AM, Cory Quammen <cory.quammen at kitware.com>
wrote:

> 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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