cellID is like is sounds. The id of the cell containing closestPoint. You can use this to access all 3 points defining the cell. I don't know what subId is for. -- View this message in context: http://vtk.1045678.n5.nabble.com/reg-vtkCellLocator-class-tp3384481p3386730.html Sent from the VTK - Users mailing list archive at Nabble.com.