    grad = vtkImageGradient()
    grad.SetDimensionality(3)
    grad.SetInputConnection(rt.GetOutputPort())
    brown = vtkBrownianPoints()
    brown.SetMinimumSpeed(0.5)
    brown.SetMaximumSpeed(1.0)
--
    grad = vtkImageGradient()
    grad.SetDimensionality(3)
    grad.SetInputConnection(rt.GetOutputPort())
    brown = vtkBrownianPoints()
    brown.SetMinimumSpeed(0.5)
    brown.SetMaximumSpeed(1.0)
--
    gradient = vtkImageGradient()
    gradient.SetInputConnection(smooth.GetOutputPort())
    gradient.SetDimensionality(2)

    # Convert the data to polar coordinates.
    # The image magnitude is mapped into saturation value,
--
    grad = vtkImageGradient()
    grad.SetDimensionality(3)
    grad.SetInputConnection(rt.GetOutputPort())

    # Elevation just to generate another scalar attribute that varies nicely over the data range
    elev = vtkElevationFilter()
--
    grad = vtkImageGradient()
    grad.SetDimensionality(3)
    grad.SetInputConnection(rt.GetOutputPort())

    # Elevation just to generate another scalar attribute that varies nicely over the data range
    elev = vtkElevationFilter()
