Dear Jochen I tried to color the line by _GL.Color(1.0f, 0.0f, 0.0f); But the rendered is still a black line. Can you help me? Regards, Jerry -- View this message in context: http://vtk.1045678.n5.nabble.com/Draw-a-2D-cross-on-vtkImageActor-tp5714166p5714184.html Sent from the VTK - Users mailing list archive at Nabble.com.