To Modify a Surface
1. Select the surface to modify.
2. Click > 
Modify Shape. The Modify Shape tab opens. If you select an analytical or a procedural surface, the same dialog box that you used for surface creation opens.
Modify Shape. The Modify Shape tab opens. If you select an analytical or a procedural surface, the same dialog box that you used for surface creation opens.3. In the Type box, select a surface type.
4. In the Segments box, type or select a value from 2 to 200 for the number of segments.
5. In the Degree box, type or select a value from 1 through 15for the degree.
6. In the Move box, select a method to constrain point movement.
7. In the Filter box, specify a filter to constrain the distribution of selected points surrounding the active point.
8. Drag one or more control mesh points to modify the surface.
9. For finer point control, specify the Adjust value and use the arrows on the tab to move a selected control point. You can also use the arrow keys.
10. Click 
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