Hi, maybe this helps... http://public.kitware.com/pipermail/vtkusers/2004-April/023779.html greets Ingo --- Dr.-Ing. Ingo H. de Boer Polytec GmbH Polytec-Platz 1-7, 76337 Waldbronn, Germany phone: ++49 7243 604 106 fax : ++49 7243 604 255