To Modify a Free Form Surface
1. Select a free-form surface in the graphics window or a surface leaf node on the GTS Tree.
2. Click Edit > Modify on the Import DataDoctor tab. The Modify tab opens.
3. In Type, select Spline, B-spline, or Bezier as the surface type. If the selected surface is analytical, Spline is the default. If the selected surface is free form, the current definition of the surface is displayed by default on the dashboard.
4. If you select Spline, specify the number of segments in the u- and v-directions.
5. If you select Bezier, specify the degree of the surface in the u- and v-directions.
6. If you select B-spline, you can specify both, the number of segments in the u- and v-directions and the degree of the surface in the u- and v- directions.
 For Bezier and B-spline surfaces, the maximum value for the surface degree in the u- and v-directions is 15. Segment values are 2 through 200.
7. Select one of the following directions for the movement of points on the surface in Move:
Normal—Moves the selected points along their own surface normal.
Normal Constant—Moves the points along the surface normal of the dragged point.
Normal Orig—Moves the points along the original surface normal.
In Surface—Moves the selected points parallel to the tangent plane.
Along Bar (Shift)—Moves points along their adjoining row or column bar.
In View (Alt)—Moves points in a plane parallel to the current view,
8. Set the Filter to one of the following options for the movement distribution of the selected points:
—Moves the selected points by the same distance as the dragged point.
—The movement of the selected points decreases linearly with distance from the dragged point. Uses a linear equation to define point motion.
—The movement of the selected points decreases smoothly with distance from the dragged point. Uses a quadratic equation to define point motion.
9. Specify a value in Adjust and use the adjacent arrows on the dashboard to move a selected control point. A red circle surrounds the selected control point.
10. Set the visual display of the surface changes to one of the following options:
—Displays a transparent or opaque preview of the modified surface.
—Displays a control mesh to use when modifying the surface.
—Displays the knot lines to use when modifying the structure of the control mesh.
11. Click to complete the surface modification.