landmarker consists of a collection of Tcl/Tk procedures that has been written and extended since 1999. The procedures use the Visualization ToolKit (VTK) library which is an open source, freely available software system ( www.kitware.com). The setting has been a multi-disciplinary research laboratory where engineers, dentists and medical doctors work together on projects involving analysis and visualization of 3-dimensional medical, mainly craniofacial, data. Often, there has been a lack of a tool for landmarking, inspection or manipulation of surfaces, and using VTK with Tcl as a script language has in many cases provided a reasonable customized solution with a reasonable amount of effort.