I have a VTK Datafile (512x128x128) that I can load into paraview & use the "Contour" filter to extract an isosurface, in about 10-15 seconds. In VTK, however, if I use a vtkDataSetReader & a vtkContourFilter to do the same thing, it takes approximately 2 minutes. How does paraview do this so fast? -- Randall Hand http://www.yeraze.com