[Paraview] Need help with UpdateExtents and RequestedExtents

[Burlen]

>  How do I tell the pipeline that the user is requesting a smaller
> sub-volume? Are there some special variables I can use? or something
> along those lines?
Set WHOLE_EXTENT to your desired subset during in RequestInformation. 
Honor UPDATE_EXTENT in your RequestData pass. It will all work out.

RequestInformation runs every time after user clicks apply in ParaView 
so what ever values they choose will be passed into the pipeline each time.


Mike Jackson wrote:
> I am trying to update a previous ParaView plugin and I am running into
> some trouble with the UpdateExtents and RequestedExtents. My problem
> is that when my plugin runs the RequestInformation iI read from the
> file to extract the origin, spacing and extent information. I then set
> them into the pipeline as such:
>
> outInfo->Set( vtkDataObject::ORIGIN(), origin, 3 );
> outInfo->Set( vtkDataObject::SPACING(), this->CurrentScalingFactor, 3 );
> outInfo->Set( vtkStreamingDemandDrivenPipeline::WHOLE_EXTENT(),
> this->PixelActual, 6 );
>
> That all seems to work fine. My plugin loads up a custom gui to allow
> the user to select a sub-volume to actually render as the volume is
> quite large and can not be rendered in 32 bit clients or even some 64
> bit clients for that matter.
>
> So I have the Custom plugin GUI talking to my custom reader so that
> values entered into the GUI are available during the RequestData()
> method of my reader class. Now here is the fun:
>
>  This code:
>
> vtkInformation* outInfo = outputVector->GetInformationObject(0);
> vtkImageData* output =
> vtkImageData::SafeDownCast(outInfo->Get(vtkDataObject::DATA_OBJECT()));
> vtkTypeInt32 updateExtent[6];
> if (outInfo->Has(vtkStreamingDemandDrivenPipeline::UPDATE_EXTENT()))
> {
> // Get the requested data extent.
> updateExtent[0] =
> (outInfo->Get(vtkStreamingDemandDrivenPipeline::UPDATE_EXTENT()))[0];
> updateExtent[1] =
> (outInfo->Get(vtkStreamingDemandDrivenPipeline::UPDATE_EXTENT()))[1];
> updateExtent[2] =
> (outInfo->Get(vtkStreamingDemandDrivenPipeline::UPDATE_EXTENT()))[2];
> updateExtent[3] =
> (outInfo->Get(vtkStreamingDemandDrivenPipeline::UPDATE_EXTENT()))[3];
> updateExtent[4] =
> (outInfo->Get(vtkStreamingDemandDrivenPipeline::UPDATE_EXTENT()))[4];
> updateExtent[5] =
> (outInfo->Get(vtkStreamingDemandDrivenPipeline::UPDATE_EXTENT()))[5];
> }
>
> will always return the entire volume space which I guess I can
> understand as that is what I put into those values during the
> RequestInformation. I was merrily just using the values that get
> pushed into my class via the custom GUI text fields. These values will
> differ from the UPDATE_EXTENT. I setup the output with the smaller
> extents and now my "RequestData()" is executed at least twice. I have
> seen this before and have no idea what I do to solve it.'
>
>  How do I tell the pipeline that the user is requesting a smaller
> sub-volume? Are there some special variables I can use? or something
> along those lines?
>
>
>    Also during the copying of the data from the file into the
> vtkImageData object I get any number of errors:
>
> Warning: In /Users/Shared/OpenSource/vtk-5.4.2/Filtering/vtkDataSet.cxx,
> line 414
> vtkImageData (0x353d380): Point array RoboMet Voxels with 1
> components, has 0 tuples but there are only -208926896 points
>
> Here are some stats about what I am trying to produce:
>
> MicronVOI: 46979.1 47526.7 48347.6 49080.1 492 495.2
> MicronActual: 46979.1 48525.1 48347.6 50078.9 490 510
> Requested Extent: 0 7440 0 8330 490 510
> PixelActual: 0 7440 0 8330 490 510
> PixelVOI: 0 2631 0 3520 0 3
> dims: 2632 3521 4
>
> All that seems correct and the data seems to copy from the file into
> the array but then I get the error above and ParaView will just crash.
>
> This is all with PV CVS, OS X intel 10.5.7, Xcode 3.1.3 tooling, cmake
> 2.6.4 and GCC 4.2 compiler.
>
>
> Any help is appreciated.
> Mike Jackson
> BlueQuartz Software  | www.bluequartz.net
> _______________________________________________
> Powered by www.kitware.com
>
> Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html
>
> Please keep messages on-topic and check the ParaView Wiki at: http://paraview.org/Wiki/ParaView
>
> Follow this link to subscribe/unsubscribe:
> http://www.paraview.org/mailman/listinfo/paraview
>