[vtkusers] problem in mapping colors

[freshy flo]

Hello all vtk users,

I have a simple code to open a STL file that works fine.  This file 
contains only one structure (bone tissue) and i'm able to give a color 
to it ((1,0.5,0);). But what I can't set so far is the a color of the 
rest of the information in the stl file (the bone marrow). I have to 
precise that the STL file are created from Binarised images.

 vtkSTLReader *sr = vtkSTLReader::New();
     sr->SetFileName ("porous.stl");

 vtkPolyDataNormals *pNormals = vtkPolyDataNormals::New();
     pNormals->SetFeatureAngle (80);
     pNormals->SetInput(sr->GetOutput());

 vtkPolyDataMapper *stlMapper = vtkPolyDataMapper::New();
     stlMapper->SetInput(pNormals->GetOutput());
    stlMapper->SetColorModeToMapScalars();
    stlMapper->ScalarVisibilityOff();
   
   
    vtkActor *stlActor = vtkActor::New();
     stlActor->SetMapper(stlMapper);
     stlActor->GetProperty()->SetColor(1,0.5,0); // bone color ???? how 
to give a color to the marrow ?????
     stlActor->GetProperty()->SetInterpolationToGouraud();

 ren->AddActor(stlActor);
 ren->SetBackground(0,0,0);

  // draw the resulting scene
 renWindow->SetSize( 300, 300 );
 renWindow->Render();
 //Start the interactor
 iren->Start();

If anyone could point me to some suggestions .....
Jean