[Paraview] CoProcessing needed fields

Thu Nov 8 19:47:50 EST 2012

Ah, I think I see what's going on now. I think it was a bug in the
generated scripts that was causing problems. Were you getting something
like the following in your script:
write_frequencies    = {'input': ['1']}

The bug was that the 1 shouldn't be in quotes. If you take that out do you
start getting the results you expect? If not, can you share your generated
Python script?

Andy

On Thu, Nov 8, 2012 at 6:41 PM, Tim Gallagher <tim.gallagher at gatech.edu>wrote:

> Andy,
>
> Thanks for the answer.
>
> What I'm doing doesn't use any writers -- I just want the CoProcessor to
> output images only. So I don't attach a writer, I just export the state and
> tell it to "Output Rendering Components". My pipeline looks like:
>
> Load file -> CellDataToPointData -> Slice
>
> This results in a RequestDataDescription:
>
> def RequestDataDescription(datadescription):
>     "Callback to populate the request for current timestep"
>     if datadescription.GetForceOutput() == True:
>         for i in range(datadescription.GetNumberOfInputDescriptions()):
>             datadescription.GetInputDescription(i).AllFieldsOn()
>             datadescription.GetInputDescription(i).GenerateMeshOn()
>         return
>
>     for input_name in simulation_input_map.values():
>        LoadRequestedData(datadescription, input_name)
>
> This means in my case, there are no fields defined inside the
> datadescription. So when I try to do the IsFieldNeeded() call in my
> adaptor, it's always false. If I print the number of fields from
> GetNumberOfFields(), I get 0.
>
> So my images when they pop out have no data -- the fields don't exist for
> them to plot. It's just the slice using the default color for the surface.
>
> I got it to work by making a new variable just under simulation_input_map:
>
> simulation_cell_fields_needed = {simulation_input_map['rest_00000.xmf']:
> ["Temperature [K]", "Density [kg/m^3]"]}
> simulation_point_fields_needed = {simulation_input_map['rest_00000.xmf']:
> []}
>
> and putting in RequestDataDescription before the loop that calls
> LoadRequestedData:
>
>     for input_name in simulation_input_map.values():
>       idd = datadescription.GetInputDescriptionByName(input_name)
>       for cell_fields in simulation_cell_fields_needed[input_name]:
>         idd.AddCellField(cell_fields)
>       for point_fields in simulation_point_fields_needed[input_name]:
>         idd.AddPointField(point_fields)
>
> When I do that, it all works.
>
> Now, I guess my question is this... Where in the exported state script
> does it say what fields there are in the data? If I do a trace, when I load
> a file, I get something like:
>
> REST_00207_xmf.CellArrays = ['APD_mass_fraction', 'APD_reaction_rate',
> 'AP_mass_fraction', 'AP_reaction_rate', 'BND_mass_fraction', 'BND\
> _reaction_rate', 'Density [kg/m^3]', 'HybridSwitch', 'N2_mass_fraction',
> 'PRD_mass_fraction', 'PRD_reaction_rate', 'Pressure [Pa]', 'Subgrid\
>  kinetic energy [m^2/s^2]', 'Temperature [K]', 'Velocity [m/s]', 'iblanks']
>
> and I expected something similar in the exported state script. But I don't
> see anything like that.
>
> Following the Fortran API, I call the ClearFieldDataFromGrid which may get
> rid of the fields that Paraview told it the pipeline needs.
>
> I could be misunderstanding something, I've never used VTK before this
> little project attempt. I can certainly send my adaptor code and python
> script if it helps clarify.
>
> Thanks again,
>
> Tim
>
> ------------------------------
> *From: *"Andy Bauer" <andy.bauer at kitware.com>
> *To: *"tim gallagher" <tim.gallagher at gatech.edu>
> *Cc: *"ParaView list" <paraview at paraview.org>
> *Sent: *Thursday, November 8, 2012 6:20:01 PM
> *Subject: *Re: [Paraview] CoProcessing needed fields
>
>
> Hi Tim,
>
> This should get set in the RequestDataDescription method in the generated
> Python script. When I first did it I thought we'd easily be able to figure
> out which fields were needed in order to update all of the required
> pipelines and/or views. Unfortunately this isn't trivial in VTK so
> basically what happens is that if a writer or view should output it
> specifies that all fields should be made available. This is the
> "datadescription.GetInputDescription(i).AllFieldsOn()" part of the
> generated python script.
>
> Answering your final question, this is something that is done
> automatically in the generated script.
>
> Andy
>
> On Wed, Nov 7, 2012 at 2:57 PM, Tim Gallagher <tim.gallagher at gatech.edu>wrote:
>
>> Hi,
>>
>> I see in the example code for
>> ParaView/CoProcessing/Adaptors/FortranAdaptors/PhastaAdaptor/PhastaAdaptor.cxx
>> calls like:
>>
>>   vtkCPInputDataDescription* idd =
>>
>> ParaViewCoProcessing::GetCoProcessorData()->GetInputDescriptionByName("input");
>>
>>   ...
>>
>>   if(idd->IsFieldNeeded("velocity"))
>>   {
>>   ...
>>
>> The only way IsFieldNeeded returns true is if that name field was added
>> with AddCellField or AddPointField.
>>
>> Where does that happen? My intuition says that the python or C++
>> processing script (generated by exporting state) would have those calls in
>> it for the datasets that are actually used. In other words, if I set up my
>> view in the GUI and I load my data and put a Slice through it and color by
>> "Velocity", I expected the script from Export State to contain a call to
>> AddCellField("Velocity"). At the very least I expected to see calls to add
>> the fields I chose to load when I loaded my sample file to set up the view.
>>
>> So is that something that I need to put in the script on my own after
>> it's exported or did I miss something? If I have to put it there myself, is
>> RequestDataDescription the correct place to put that?
>>
>> Thanks,
>>
>> Tim
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>
>
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