[vtkusers] vtkVRMLExporter,string: nan nan nan

[petr zlamal]

Hi vtkusers,
I have a problem with vtkVRMLExporter. Output from vtkVRMLExporter 
includes some rows with string "nan nan nan,"  instead of float numbers:
             .......
            0.00392154 0.999992 -0,
           0.999992 0.00395254 -0,
           -0.999992 -0 -0.00393698,
           nan nan nan,
           -0.57735 -0.57735 -0.57735,
           -0.999992 -0 -0.00392154,
           -0 0.707107 -0.707107,
          .........
What the mean string "nan nan nan"(perhaps not a number) and mainly why 
is there???. This string generated errors in vrml viewer (gtklookat).

I have following simple code for writting VRML file:

                self.renWin=vtk.vtkRenderWindow()
                self.renWin.AddRenderer(input)
                self.renWin.Render()
                self.vrml=vtk.vtkVRMLExporter()
                self.vrml.SetInput(self.renWin)
                self.vrml.SetFileName(unicode(file))
                self.vrml.Write()
                self.renWin.Finalize()


where variable input is output from the vtkRenderer.

Thanks for any help
Vepro