Surfaces > Skin

Lets you create a surface by “skinning” a NURBS surface across cross-section curves.

Skinning Options

Skinning Mode

This option controls the V parameterization of the new surface.

Interpolate – Place V isoparametric curves at the locations of the original curves. This is the default setting.

Cubic Fit – This option cannot be used when creating a degree 1 surface.

Place V isoparametric curves according to a fitting algorithm. In some cases, this option can eliminate unwanted variations in the skinned surface.

Topology

Open – Leave the resulting surface open.

Closed – Connect the first curve to the last curve to create a closed (periodic) surface.

U Knot Spacing

The U direction of the surface runs along the original construction curves. This option controls how the U parameters relate to the actual surface.

Uniform – The isoparametric curves corresponding to edit points on the original construction curves have integral parameters: the first edit point is parameter 0.0, the second is 1.0, and so on.

Arc Length – The new edit points for the curve are parameterized by the average length along the original construction curves at those points.

The starting edge of the surface has the parameter 0.0, and the opposite edge has the parameter equal to the average total length of the original construction curves.

V Knot Spacing

The V direction of the surface runs between the original construction curves. This option controls how the V parameters relate to the actual surface.

Uniform – The isoparametric curves corresponding to the original construction curves have integral parameters: the first edit point is parameter 0.0, the second is 1.0, and so on. This option only applies to Interpolate skinning mode.

Chord Length – The edit points of the new curve are parameterized by the length of the surface.

The starting edge of the surface has the parameter 0.0, and the opposite edge has the parameter equal to the length of the surface.

Surface Degree

The degree of the V direction of the new surface: 1 (linear), or 3 (cubic, the default).

This option is only available when Skinning Mode is Interpolate.

Number of Spans

This option controls the number of spans between the original isoparametric curves of the skin surface (as determined by the Skinning Mode).

• A value of 1 creates no additional isoparametric curves, besides the original ones.
• A value of 2 creates two spans between the original isoparametric curves, so one additional isoparametric curve is created between each pair of original isoparametric curves.
• A value of 3 creates three spans, and two additional isoparametric curves between each pair of original isoparametric curves, and so on.
Rebuild

Before building the surface, rebuild the other construction curves to match the parameterization of the first curve.

When using this option, make sure that the first curve you click has the parameterization you want for the new surface.

NoteIf Rebuild is on, the U knot spacing is affected.
Auto Recalc

Automatically update the surface as curves are added.

This option changes the procedure for using the tool. When Auto Recalc is on, you must hold down Shift when you click more curves to add to the surface.

Create History

Save the history of the new surface for later editing. If you turn Create History on, when you modify the curves that were used to create the surface, the surface updates.