b-Splines

Next we'll import the same points as the control points for a basis spline (b-spline), except this time on a sketch based on the ZX-Plane. Select ZX-Plane in the Sketch or Plane box, and select Curve (B-Spline) in the Import Points As area. Leave everything else the same and click Import.

Switch back to Alibre Design and turn the part until you see the curve on the ZX-Plane.

Point Import Wizard allows you to specify the polynomial order of the b-spline it produces, and it uniformly distributes spline knots. The higher the order, the smoother the curve because each knot of the curve is affected by more control points. With an order of 2, the b-spline is essentially a set of connected lines, but with an order of 4 (the default for Alibre Design), the curve is much smoother.

Change the order to 3 as shown below, select the sketch you created with the first b-spline import above, and click Import again. Note that the result is not as smooth as the first. This is because the order is a lower number.