Hi all, Finally I found the problem. The reason that vtkProPicker pick wrong is I used QVTKOpenGLWidget not QVTKWidget. I wish someone can fix the bug. -- View this message in context: http://vtk.1045678.n5.nabble.com/Question-about-Pick-vtkActor2D-tp5744570p5744571.html Sent from the VTK - Users mailing list archive at Nabble.com.