    icp = vtkIterativeClosestPointTransform()
    icp.SetSource(source)
    icp.SetTarget(target)
    icp.GetLandmarkTransform().SetModeToRigidBody()
    # icp.DebugOn()
    icp.SetMaximumNumberOfIterations(20)
--
    icp = vtkIterativeClosestPointTransform()
    icp.SetSource(source_polydata)
    icp.SetTarget(tpd.GetOutput())
    icp.GetLandmarkTransform().SetModeToRigidBody()
    icp.SetMaximumNumberOfLandmarks(100)
    icp.SetMaximumMeanDistance(.00001)
