code: def isInside(self, point, tol=0.0001):
          
          poly = self.polydata(True)
          points = vtk.vtkPoints()
          points.InsertNextPoint(point)
          pointsPolydata = vtk.vtkPolyData()
          pointsPolydata.SetPoints(points)
          sep = vtk.vtkSelectEnclosedPoints()
          sep.SetTolerance(tol)
          sep.CheckSurfaceOff()
          sep.SetInputData(pointsPolydata)
          sep.SetSurfaceData(poly)
          sep.Update()
          return sep.IsInside(0)
docs: Return True if point is inside a polydata closed surface.