code: def normalize(self):
          
          cm = self.centerOfMass()
          coords = self.coordinates()
          if not len(coords):
              return
          pts = coords - cm
          xyz2 = np.sum(pts * pts, axis=0)
          scale = 1 / np.sqrt(np.sum(xyz2) / len(pts))
          t = vtk.vtkTransform()
          t.Scale(scale, scale, scale)
          t.Translate(-cm)
          tf = vtk.vtkTransformPolyDataFilter()
          tf.SetInputData(self.poly)
          tf.SetTransform(t)
          tf.Update()
          return self.updateMesh(tf.GetOutput())
docs: Shift actor's center of mass at origin and scale its average size to unit.