To highlight back-facing surfaces

Display back faces of an open or inverted surface in red.

The direction of the surface normal vector determines front or back facing.

1. Display the model in a shaded view.
2. Select View tab > Appearance > Back-Face Highlight.

   The CAD model shows back-facing surfaces in red.

   

3. Rotate the model so the view is reversed.

   The colouring changes to show the new back-facing surface.