[vtkusers] Using a vtkImagePlaneWidget on a vtkImageData

[Toh Da Jun]

Using java, I've create a 3D volume render by using
    vtkImageData mediumVolume            =   null;
        mediumVolume = new vtkImageData();
        mediumVolume.SetWholeExtent(0, m_iDimension_X-1,
                                    0, m_iDimension_Y-1,
                                    0, m_iDimension_Z-1);
        mediumVolume.SetUpdateExtent(mediumVolume.GetWholeExtent());
        mediumVolume.SetExtent(mediumVolume.GetWholeExtent());
        [ other initialisation lines ]      
        mediumVolume.SetOrigin(0,0,0);
        mediumVolume.SetSpacing(1,1,1);
        mediumVolume.SetScalarTypeToFloat();

next I tried to use the vtkImagePlaneWidget to provide 2D profiles of 
the mediumVolume. Here are the codes...
        imagePlaneWidget = new vtkImagePlaneWidget();
        imagePlaneWidget.DisplayTextOn();
        imagePlaneWidget.SetInput(mediumVolume);
        imagePlaneWidget.SetPlaneOrientationToXAxes();
        imagePlaneWidget.SetSliceIndex(10);
        imagePlaneWidget.GetPlaneProperty().SetColor(0,1,0);
        imagePlaneWidget.SetInteractor( displayCanvas.getIren() );
        imagePlaneWidget.On();
        imagePlaneWidget.InteractionOff();
        imagePlaneWidget.RestrictPlaneToVolumeOn();

Problems:
1. The imageplane shows nothing.
2. If imagePlaneWidget.InteractionOn() was used, then the program will 
crash.

I've gone through the examples for vtkImagePlaneWidget...where the 
HybridCxxTests uses vtkVolume16Reader to read in a file. It uses a 
GetOutput() to pass a vtkImageSource to 
imagePlaneWidget.SetInput(vtkDataSet *input);

    vtkVolume16Reader v16 = new vtkVolume16Reader();
    vtkimagePlaneWidget ipw = new vtkimagePlaneWidget();
    ipw.SetInput(v16.GetOutput());

since vtkImageData is a concrete implementation of vtkDataSet, why does 
it work?


toh da jun