    threshold = vtkThresholdPoints()
    threshold.SetInputConnection(reader.GetOutputPort())
    threshold.ThresholdByUpper(200)

    line = vtkLineSource()
    line.SetResolution(1)
--
    threshold = vtkThresholdPoints()
    threshold.SetInputConnection(reader.GetOutputPort())
    threshold.ThresholdByUpper(200)

    mask = vtkMaskPoints()
    mask.SetInputConnection(threshold.GetOutputPort())
--
    threshold = vtkThresholdPoints()
    threshold.SetInputConnection(reader.GetOutputPort())
    threshold.ThresholdByUpper(275)

    streamers = vtkStreamTracer()
    streamers.SetInputConnection(reader.GetOutputPort())
--
        ThresholdIn = vtkThresholdPoints()
        ThresholdIn.SetInputData(Grid)
        ThresholdIn.ThresholdByUpper(.5)
        # Display spheres at the vertices remaining in the cube data set after
        # it was passed through vtkThresholdPoints.
        Vertices = vtkGlyph3D()
