title: Viewer Materials (wrong conversion from Revit shaded view)
body: <p>I'm working on a Revit Mechanical Model (Duct, Pipes and Cable Trays).
  I setup a Shaded view in Revit with a custom color scheme (organized applying different material to each System Type). The graphics is clean and works.</p>
  
  <p>When we translate the Model to the Forge platform, the result is a wrong color scheme in the Viewer. It looks like the fittings got wrong material after model translation.</p>
  
  <p>In this picture you can see:
   - on the left, the Revit Model view (shaded style),
   - on the right, the Forge Viewer with wrong colors.</p>
  
  <p><img src="https://i.stack.imgur.com/T5xDa.jpg" alt="image: RevitView to ForgeViewer"></p>
  
  <p>We tried with different models but the problem is always the same. is this a bug? anyone got this kind of issue?</p>