[vtkusers] 3D volume rendering

[Artem Babayan]

Hello,

I am trying to obtain rendering of 3D concentration data defined on
structured grid. An objective is to get semi-transparent 3D volume.
For some reasons what I am apparently getting is the slice of data on
some surface (??) (see attached screenshots). I am surely doing
something wrong, but what? The source code is below.

Thank you for any help

Best wishes
Artem

    //read the volume from file
    vtkSmartPointer<vtkStructuredPointsReader> reader_conc=
                    vtkSmartPointer<vtkStructuredPointsReader>::New();
    reader_conc->SetFileName("conc_3d.vtk");

    //Create a mapper
    vtkSmartPointer<vtkFixedPointVolumeRayCastMapper> mapper_conc =
                 vtkSmartPointer<vtkFixedPointVolumeRayCastMapper>::New();
    mapper_conc->SetInput(reader_conc->GetOutput());

    //create volume
    vtkSmartPointer<vtkVolume> volume =
                          vtkSmartPointer<vtkVolume>::New();

   //let it be semitransparent for all data
    vtkPiecewiseFunction *oTFun = vtkPiecewiseFunction::New();
    oTFun->AddPoint(0., 0.5, 0.5, 1.0);
    oTFun->AddPoint(1.5, 0.5, 0.5, 1.0);

  //color transfer function -- blue for empty and red for high concentration
    vtkColorTransferFunction *cTFun = vtkColorTransferFunction::New();
    cTFun->AddRGBPoint(   0.0, 0.0, 0.0, 1 );
    cTFun->AddRGBPoint(  1e-25, .0, .1, .8 );
    cTFun->AddRGBPoint( 1e-15, .1, .3, 0.6 );
    cTFun->AddRGBPoint( 1.3, 1.0, .0, 0.0 );

//set volume property
    vtkVolumeProperty *property = vtkVolumeProperty::New();
    property->SetScalarOpacity(oTFun);
    property->SetColor(cTFun);
    property->SetInterpolationTypeToLinear();
    property->SetScalarOpacityUnitDistance(2.0);

    volume->SetMapper(mapper_conc);
    volume->SetProperty(property);

      // a renderer and render window
    vtkSmartPointer<vtkRenderer> renderer =
                            vtkSmartPointer<vtkRenderer>::New();
    renderer->SetBackground(0.9, 0.9, 0.9);
    renderer->ResetCamera();
    renderer->GetActiveCamera()->Dolly(1);
    renderer->ResetCameraClippingRange();

    vtkSmartPointer<vtkRenderWindow> renderWindow =
                            vtkSmartPointer<vtkRenderWindow>::New();
    renderWindow->SetSize(900, 600);
    renderWindow->AddRenderer(renderer);

      // add the volume to renderer
    renderer->AddVolume(volume);

      // an interactor
    vtkRenderWindowInteractor *iren = vtkRenderWindowInteractor::New();
    iren->SetRenderWindow(renderWindow);

      renderWindow->Render();
      // begin mouse interaction
       iren->Start();
    return 0;
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