Just as you used smoothing groups to distinguish different parts of the fuselage, you can use smoothing groups to distinguish the different materials in the canopy.

Set up the lesson:

• Continue working from the previous lesson.

Use smoothing groups to distinguish the metal parts from the glass parts:

1. On the ribbon Properties panel drop-down portion, click (SmGroups).

   3ds Max opens the Smoothing Groups dialog.

2. In the Smoothing Groups dialog, assign the metal polygons a value of 32.
   
   NoteYou used this value for the engine cowl as well, but remember that the P-47 fuselage and the Canopy are two different objects, so the smoothing-group values don’t overlap.
   
3. Press Ctrl+I to invert the selection again, and then assign the glass faces a smoothing-group value of 24.
   
4. Close the Smoothing Groups dialog.

Use NURMS smoothing to preview the canopy:

1. Exit the (Polygon) sub-object level.
2. Press Alt+X to turn off X-Ray display.
   
3. On the ribbon Edit panel, turn on (NURMS). On the ribbon Use NURMS panel, increase the value of Iterations to 2.
   

   This is far too much smoothing. As with the fuselage, you now need to take smoothing groups into account.

4. On the ribbon Use NURMS panel drop-down portion Separate By drop-down list, turn on Smoothing Groups.
   

   Now the metal and glass portions of the canopy appear more distinct.

   

   With smoothing groups taken into account, there are well-defined edges between the glass and the metal parts of the canopy. On the other hand, the shape of the windshields is far too rounded. You will fix that in the next procedure.

5. Turn off (NURMS).