    warp = vtkWarpScalar()
    warp.SetInputConnection(geometry.GetOutputPort())
    warp.SetScaleFactor(-0.1)

    # Use vtkMergeFilter to combine the original image with the warped geometry.
    merge = vtkMergeFilter()
--
    warp = vtkWarpScalar()
    warp.SetInputData(bessel)
    warp.XYPlaneOn()
    warp.SetScaleFactor(0.5)

    # Mapper and actor.
--
    warp = vtkWarpScalar()
    warp.SetInputConnection(appendF.GetOutputPort())
    warp.UseNormalOn()
    warp.SetNormal(1.0, 0.0, 0.0)
    warp.SetScaleFactor(2.5)

