Periodic curve

A periodic curve is a smooth closed curve. Periodic curves stay smooth when you edit them.

Periodic Surface

Periodic surfaces are closed surfaces (such as a cylindrical surface) that can be deformed without developing kinks. Periodic surfaces are automatically created when the input curves are periodic.

Smooth

Controls kink removal.

The Smooth option is only available when objects have not been selected.

Yes

Smooths any kinks in the curve and moves control points to make a smooth curve.

No

Control point locations are not changed or changed minimally (only one point may move) and only the knot vector is altered.

Smooth=Yes (left) and Smooth=No (right.

Non‑periodic curve

A non-periodic curve is a closed curve with a kink at the start/end of the curve. Deforming non-periodic curves near the start of the curve may result in kinks.

Non‑periodic surface

A non-periodic surface is a closed surface with a kink at the start/end of the surface. Deforming non-periodic surfaces near the start of the surface may result in kinks. Non-periodic surfaces are automatically created when the input curves are non-periodic.

Non-periodic surfaces and curves deform with sharp corners at kinks.