[vtkusers] Volume rendering a dataset of only 2 scalars values,

[Paul McGuinness]

Hi vtk users,

I have created a sphere in vtkImagedata format, it is built consisting of
two scalar values, 0 and 1. Scalar value 0 is set to all points inside and
outside the sphere and scalar value 1 is used for the boundary of the
sphere.

I can create a isosurface (contour surface) of my sphere simply by using:
contour->SetValue(0,1);

Now I need to create a volume rendering of this data. I am using the
following:

vtkPiecewiseFunction *opacityTransferFunction1 = vtkPiecewiseFunction::New();
   opacityTransferFunction1->AddPoint(1,   0.5);

vtkColorTransferFunction *colorTransferFunction1 = vtkColorTransferFunction::New();
    colorTransferFunction1->AddRGBPoint(1, 1.0, 1.0, 1.0);

vtkVolumeProperty *volumeProperty1 = vtkVolumeProperty::New();
    volumeProperty1->SetColor(colorTransferFunction1);
    volumeProperty1->SetScalarOpacity(opacityTransferFunction1);
    volumeProperty1->ShadeOn();
    volumeProperty1->SetInterpolationTypeToLinear();

vtkVolumeRayCastMIPFunction  *MIPFunction= vtkVolumeRayCastMIPFunction::New();
vtkVolumeRayCastMapper *volumeMapper1 = vtkVolumeRayCastMapper::New();
   volumeMapper1->SetVolumeRayCastFunction(MIPFunction);
   volumeMapper1->SetInput(img->GetOutput());

BUT I am getting nothing! Am I using this correctly? Can someone please
help to get this to work? I appreciate any suggestions.

Many Thanks,
Paul.