[vtkusers] vtkUnstructuredGrid to vtkImageData

[Dan Lipsa]

Hi,

I am trying to convert a tetrahedral grid (tetraFoam) into a (3D)
vtkImageData (regularFoam) because I try to compute an average of all
attributes of this dataset over several time-steps.
I use vtkProbeFilter to do the conversion and do the following steps:

VTK_CREATE (vtkImageData, regularFoam);
    regularFoam->SetExtent (0, pointsPerAxis - 1,
			    0, pointsPerAxis - 1,
			    0, pointsPerAxis - 1);
    regularFoam->SetOrigin (origin.x, origin.y, origin.z);
    regularFoam->SetSpacing (spacing.x, spacing.y, spacing.z);

    VTK_CREATE (vtkProbeFilter, regularProbe);
    regularProbe->SetSource (tetraFoam);
    regularProbe->SetInput (regularFoam);

    VTK_CREATE (vtkShrinkFilter, shrink);
    shrink->SetInputConnection (regularProbe->GetOutputPort ());
    shrink->SetShrinkFactor (0.9);

    m_actor->SetUserMatrix (modelView);
    m_mapper->SetLookupTable (colorTransferFunction);
    m_mapper->SetInputConnection (shrink->GetOutputPort ());
    update ();


The origin, and spacing for vtkImageData are set from the bounding box
of the tetrahedral grid.

The tetrahedral dataset looks right when I display it, however the
regular grid is displayed gray (no color map is applied) which leads
me to believe that no attributes were set by the probe filter.
Does anyone have any suggestions on what could be wrong here.

Thanks a lot,
Dan