To Automatically Create Spline Surfaces
1. Click Restyle > Auto Surface. The Auto Surface tab opens.
2. To define the scope of the surface, click , and then click a button:
—Generates a surface over the entire faceted model.
—Generates a surface over a selected closed loop area on the facet feature. Select contour curves that define a closed loop area:
Click and select the required curves. The contour curves form a closed curve boundary. After you select a valid loop, arrows appear on this loop to indicate the default side that is selected for creating the surface.
If the contour curves form a loop that lies within the main loop, the area within the loop is excluded from the closed loop area.
If required, click to flip the side on which the patch structure is created.
To remove contour curves from the closed loop area, click and select the curves.
By default, a patch structure is created on the side indicated by the arrow on the selected loop.
3. Click to enter the patch structure creation phase.
4. If required, click Parameters, and specify values for the curve generation settings.
To activate the Granularity setting, change the default (-1) value to a positive integer.
To set the Character level, type or select a number from 0 to 1.
5. Create the patch structure as follows:
Create the patch structure by selecting the internal curves.
To designate a curve as an internal curve, click and select the curve.
To remove a curve from the selected internal curves, click and select the curve.
The curves designated as internal curves are included in the patch structure. Curves that you removed from the selected internal curves are excluded from the patch structure.
If the selected curves meet the criteria for a patch structure and no further subdivision is required, proceed to the next step.
 If required, you can create more patches automatically as follows:
1. Specify the number of patches in the Add patches box. The total number of patches created in the patch structure is approximately equal to this number.
2. Click . The patch structure is generated automatically.
If you are satisfied with the patch structure, you can directly proceed to the surface creation phase.
3. If required, click Undo to remove the newly created patch structure. Specify a new value in the Add patches box. Click Parameters and specify values for Granularity and Character level. Repeat this step until you get a good patch structure.
If a curve in the patch structure has a tangent constraint, the surfaces that share this curve as a common boundary are tangent to each other. In this case, a symmetric tangency is imposed between the surfaces. By default the constraint type is set to tangent.
6. If required, change the curve constraint by clicking the constraint from the Constraints tab and selecting the internal curve. Alternatively, select one or more internal curves and select the required constraint type.
The tangent constraint is represented in black while the position constraint is represented in red.
You can click and repeat steps 2 to 6 to redefine the closed loop curve boundary and the patch structure.
7. Click to enter the surface creation phase.
8. If required, use the Resolution box to better the quality of the surface.
9. Click . The surface is automatically created from the patch structure.
You can click and repeat steps 3 to 9 to redefine the patch structure and the surface.
10. Click .