[Paraview] Failed to determine the LookupTable being used

[Sgouros, Thomas]

Hi Cory

Thank you for that. I'd already been to those two places and not found what
I was asking for there. I see how to get information from my data, and
that's how I know it's a vtkMultiBlockDataSet, but I just don't understand
how to translate what is there to what I need. I want to know what data
values (scalar and vector) are in this dataset, and what their ranges are.
I'm sure I'm just not calling something by the right name, but I'm
wandering up and down the help() data and not really finding anything
relevant.

Thank you,

 -Tom


On Wed, Apr 18, 2018 at 9:34 AM, Cory Quammen <cory.quammen at kitware.com>
wrote:

> Thomas,
>
> Have a look at the wiki page on Python Scripting in ParaView: https://www.
> paraview.org/Wiki/ParaView/Python_Scripting
>
> Search for GetDataInformation if you want to jump right to interrogating
> the data set, but the rest of the page is likely of interest as well.
>
> For comprehensive documentation of Python functions, please see
> https://www.paraview.org/ParaView/Doc/Nightly/www/py-doc/index.html.
>
> Cheers,
> Cory
>
> On Wed, Apr 18, 2018 at 8:05 AM, Sgouros, Thomas <thomas_sgouros at brown.edu
> > wrote:
>
>> 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.
>>>
>>
>>
>
>
> --
> Cory Quammen
> Staff R&D Engineer
> Kitware, Inc.
>
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