[Paraview] Failed to determine the LookupTable being used

[Cory Quammen]

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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