[vtkusers] vtkOBJExporter: Output Colors?

[Stewart.Dickson at noaa.gov]

Hello,

I am building a Vtk pipeline containing a vtkContourFilter containing 11
values and a color LUT scaled to the range of the input data.  But, in my
output '.OBJ' file, I see one color -- WHITE.

I export the vtkContourFilter output Wavefront '.OBJ' as follows:

vtkOBJExporter objxport
objxport SetInput renWin
objxport SetFilePrefix $outFilePrefix
objxport Write

When I add:
renWin Render
I see a nice picture of my rainbow-colored set of iso-surfaces

vtkOBJExporter also exports a $outFilePrefix.mtl file, containing
rendering attributes for the polygon geometry stored in the
$outFilePrefix.obj file
I am expecting, in my output $outFilePrefix.mtl, I see:
# wavefront mtl file written by the visualization toolkit

newmtl mtl1
Ka 1 1 1
Kd 1 1 1
Ks 1 1 1
Ns 1
Tf 0.4 0.4 0.4
illum 3

I see one material with opacity 0.6, as I specified, but -- WHITE.
In $outFilePrefix.obj, there is one group, g grp1 and one material
reference, usemtl mtl1.

How does one output the color->geometry assignmenmts from the
vtkContourFilter -> vtkPolyDataMapper -> vtkActor rendering pipeline?

Thanks,

-Stewart Dickson, Principal Scientific Subject Matter Expert in
Visualization
NOAA National Climatic Data Center