[vtkusers] need help using vtkHyperOctree and vtkHyperOctreeContourFilter

[Rob Harris]

I am still unable to plot correct contours on a vtkHyperOctree. Again, as a
simple test case I would like to plot lines of constant x on a unit square.
For this, I have defined a 2D vtkHyperOctree of 16 cells (4x4). The grid is
plotted correctly, but the contours are incorrect. Here is the my xml grid
file (vto file):

<?xml version="1.0"?>
<VTKFile type="HyperOctree" version="0.1" byte_order="LittleEndian"
compressor="vtkZLibDataCompressor">
  <HyperOctree Dimension="2" Size="1 1 0.5" Origin="0.5 0 0">
    <Topology>
      <DataArray type="Int32" Name="Topology" NumberOfTuples="21"
format="ascii" RangeMin="0" RangeMax="1">
        0 0 1 1 1 1
        0 1 1 1 1 0
        1 1 1 1 0 1
        1 1 1
      </DataArray>
    </Topology>
    <PointData Scalars="LinearFunction">
      <DataArray type="Float64" Name="LinearFunction" format="ascii"
RangeMin="0.125" RangeMax="0.875">
        0.125 0.375 0.125 0.375 0.625 0.875
        0.625 0.875 0.125 0.375 0.125 0.375
        0.625 0.875 0.625 0.875
      </DataArray>
    </PointData>
    <CellData>
    </CellData>
  </HyperOctree>
</VTKFile>

I read in this file and render with the code below:

#include "vtkActor.h"
#include "vtkDataSetMapper.h"
#include "vtkPolyDataMapper.h"
#include "vtkOutputWindow.h"
#include "vtkPointData.h"
#include "vtkCellData.h"
#include "vtkRenderer.h"
#include "vtkRenderWindow.h"
#include "vtkRenderWindowInteractor.h"
#include "vtkHyperOctree.h"
#include "vtkXMLHyperOctreeReader.h"
#include "vtkProperty.h"
#include "vtkHyperOctreeContourFilter.h"
#include "vtkLookupTable.h"
int main(int argc, char* argv[])
{
  int NCONTOURS = 5;
  vtkOutputWindow::GetInstance()->PromptUserOn();

  // read in *.vto grid
  vtkXMLHyperOctreeReader *xmlReader=vtkXMLHyperOctreeReader::New();
  xmlReader->SetFileName(argv[1]);
  xmlReader->Update();

  vtkHyperOctreeContourFilter *contour=vtkHyperOctreeContourFilter::New();

  double
*range=xmlReader->GetOutput()->GetPointData()->GetScalars()->GetRange();
  contour->SetNumberOfContours(NCONTOURS);
  contour->GenerateValues(NCONTOURS,range[0],range[1]);
  contour->SetInputConnection(0,xmlReader->GetOutputPort(0));
  contour->Update();

  vtkPolyDataMapper *smapper;
  smapper=vtkPolyDataMapper::New();

  vtkLookupTable *lut3d = vtkLookupTable::New();
  lut3d->SetHueRange(0.667,0.0);
  smapper->SetInputConnection(0,contour->GetOutputPort(0));
  smapper->SetLookupTable(lut3d);

smapper->SetScalarRange(xmlReader->GetOutput()->GetPointData()->GetScalars()->GetRange());

  // setup actor
  vtkActor *actor = vtkActor::New();
  actor->SetMapper(smapper);

  // render now
  vtkRenderer *ren = vtkRenderer::New();
  ren->AddActor(actor);

  vtkRenderWindow *renWin = vtkRenderWindow::New();
  renWin->AddRenderer(ren);
  vtkRenderWindowInteractor *iren = vtkRenderWindowInteractor::New();
  iren->SetRenderWindow(renWin);
  renWin->SetFullScreen(1);
  renWin->Render();
  iren->Start();

  // free memory here
  xmlReader->Delete();
  smapper->Delete();
  actor->Delete();
  ren->Delete();
  renWin->Delete();
  iren->Delete();
  return 0;
}

Using the above, the grid is rendered correctly but the contours are
completely incorrect. I must have something fundamentally wrong here, and I
am unable to find any documentation to point me in the right direction. I
would be extremely grateful if anyone could help me figure this out.

Thanks,

-Rob
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