With the 30 Sections and 30 Spans specified for the original sphere in this lesson, the large space between isoparms in the mouth region makes it impossible to create a subtle shape for the lips.

To overcome this problem, you must insert isoparms in the mouth region before sculpting.

To insert additional isoparms

1. Right-click Egghead and select Isoparm from the marking menu.
2. From the Toolbox, choose the Select Tool.
   
3. Click the horizontal isoparm below the nose and shift-click the next two below it so they become yellow.
   
4. Select Edit NURBS > Insert Isoparms > . In the options window, turn on Between Selections, enter a value of 2 for # Isoparms to Insert, then click Insert.
   

   This inserts two extra isoparms between each pair of selected isoparms, for a total of four extra isoparms. This provides enough CVs to create subtlety in the mouth.

   You might want to add vertical isoparms at the lips in a similar way. The extra isoparms would also be useful if you were to later enhance the shape of the nose. Insert isoparms only where needed. More isoparms means slower processing speed.

   In any case, do not change the number of isoparms by editing the original number of Sections and Spans in the makeNurbSphere history node. This will reshape your sculpted surface undesirably.

To sculpt a mouth for the character

1. Select the Sculpt Geometry Tool again.
2. Select the Push operation. Enter 0.2 for Radius(U). In the Stroke tab, make sure Reflection is turned on.
3. Starting at the center of the area appropriate for the indentation between the lips, stroke outward from the center. It’s best to start the stroke with the dual icons on top of one another (in other words, only one icon is displayed).
4. Select the Pull operation and set the Radius(U) to 0.3. Using a similar technique as for the prior step, stroke the upper lip. Repeat for the lower lip.
   
   Note

   It might be easier to push or pull the lips with the Ref. Vector set to Z Axis. This moves the region you stroke in the world Z-Axis direction. The default Normal setting moves the region in a direction normal (perpendicular) to the surface. Because the normal direction on a lip might be up, down, or straight out, depending on the part of the lip you stroke, there’s more possibility of undesired results when you use the Normal setting.