In the next steps, you’ll become familiar with features of the Sculpt Geometry Tool. With this tool, you use your mouse or stylus to push, pull, or smooth a surface’s shape without selecting or displaying CVs. After you practice sculpting the surface, you’ll erase your practice strokes then begin sculpting Egghead’s features.

To practice sculpting using basic sculpting operations

1. With Egghead selected, select Edit NURBS > Sculpt Geometry Tool > . In the Tool Settings window, click Reset Tool, and make sure the Sculpt parameters are displayed.

   In the Sculpt Parameters section, there are a number of operations for sculpting a surface. Each affects the region of the surface where you drag (stroke) your mouse or stylus relative to the surface normals:

   
   • The Push operation depresses the surface in the region of the stroke.
   • The Pull operation raises the surface in the region of the stroke.
   • The Smooth operation diminishes bumps or ridges where you drag.

   Smoothing works by averaging the position of all features within the brush radius with all other nearby features.

   • The Relax operation paints over bumps to relax most of the out of place surface features.

   Unlike smoothing, Relax works by only averaging the largest surface anomalies so that the overall shape is maintained.

   • The Erase operation eliminates the effects of the other four operations.

   The Erase operation works up to the last time you saved the scene or clicked the Update button to the right of Erase Surface.

2. Experiment with each of the five operations on the surface. Don’t be concerned with the results. Just become familiar with the response to your mouse strokes.

   By default, Push and Pull strokes deform the surface in a direction normal (perpendicular) to the surface. To create the resulting deformation more accurately, use Push and Pull strokes in a front, side, or top view while examining the results in a separate perspective view. Tumble the perspective view regularly for the best visual feedback.

   When you position the mouse pointer on the surface, it changes to a red sculpt icon that shows an abbreviation for the name of the operation you are performing. For instance, Ps stands for Push.

   The red icon also displays the radius of the region affected by the stroke. The Radius(U) value changes the radius.

3. Select the Erase operation and click the Flood button. This erases all your changes.
   
4. Select the Pull operation and enter a Radius(U) of 0.25, then drag between a pair of horizontal isoparms without crossing either.

   This has no effect because the stroke radius didn’t make contact with the CVs of either isoparm. Regardless of which operation you use, only CVs are affected by the strokes.

5. Change the Radius(U) to 2 and repeat the prior strokes.
   

   The strokes alter the surface because the radius overlaps the CVs. As this example shows, you need to make sure the radius is big enough to influence the desired CVs. It’s common to change the radius many times during a sculpting session.

   If you prefer to affect a small region without increasing the radius, you can add CVs to the region by inserting more isoparms. You’ll do this later in the lesson.

6. Flood-erase the changes to the surface as you did previously.
7. Select the Pull operation with a Radius(U) of 0.5. Drag along a vertical isoparm. For comparison, drag along a horizontal isoparm.
   

   The vertical stroke creates a thinner ridge than the horizontal stroke because the density of vertical isoparms is greater. The number of underlying CVs and their positioning affects the outcome of your strokes.

   Tip

   You can alternatively adjust the radius of the Sculpt Geometry Tool using a Hotkey. Move the tool over the object, press and hold the b Hotkey and drag left or right. The circle on the object with numerical radius value represents the size of your tool. Stroke on the object to try out a new size.

8. Flood-erase the changes to the surface as you did previously.
9. Rotate the camera view so the X axis of the View Axis points toward you. Draw a vertical Pull stroke again.
   

   As your stroke nears the center of Egghead, a kink occurs. It’s challenging to alter a surface symmetrically in a region where many isoparms converge at a single point, called a pole. Always consider the position of isoparms as you sculpt a surface. In general, sculpt where isoparms are evenly, regularly distributed.

10. Erase all changes again, then reposition the camera view so the Z-axis of the View Axis points toward you.
    Tip

    If the Sculpt Geometry Tool is selected but not the surface you want to work on, right-click the surface and select Select from the marking menu.