Hi Wenlong, Maybe you can have a look at this example, it might be your solution. http://www.vtk.org/Wiki/VTK/Examples/Cxx/PolyData/ExternalContour Bye -- View this message in context: http://vtk.1045678.n5.nabble.com/How-to-use-vtkFeatureEdges-tp5714174p5714190.html Sent from the VTK - Users mailing list archive at Nabble.com.