Hi David, This is exactlly what i want, but the sphere must be fix and in the same position, however in the example that you suggested to me, the sphere position was changing. Thank you. -- View this message in context: http://vtk.1045678.n5.nabble.com/moving-actor-tp4895490p4895644.html Sent from the VTK - Users mailing list archive at Nabble.com.