Least Squares by Number
This Method lets you adjust the number of poles in the control polygon.
If the number of poles is lower than the number of data points or vertices, the curve is fit using the least squares method.
Generally, the more poles in the control polygon, the better the curve will fit a regular shape. In the following illustration, the line string on which the B-splines were based is shown as a solid line. The control polygons are displayed as dashed lines.