2011

Once the spline is created, many people prefer changing the shape of the
spline using control vertices because of the fine control this method provides.
With this method, you can also specify lower or higher degree polynomials,
including degree 1 (linear), degree 2 (quadratic), degree 3 (cubic), and so on
up to degree 10.
Create Splines Using Fit Points
When you create splines using fit points, the resulting curve passes through
the specified points, and is influenced by the spacing of mathematical knots
in the curve.
You can choose the spacing of these knots with the knot parameterization
option, which will result in different curves as shown in the example.
NOTE There is no best choice for knot parameterization for all cases. The chord
length parameterization is commonly used, and the square root (centripetal)
parameterization often produces better curves depending on the data set.
When the Tolerance value is set to 0, the spline passes directly through the
fit points. With larger tolerance values, the spline passes near the fit points.
Optionally, you can specify the tangent direction for the spline at each end.
NOTE The fit point method always results in a degree 3 spline.
Special Cases
You can create a spline with a parabolic shape by specifying a degree 2 spline
created with exactly 3 control vertices as shown on the left. Degree 3 splines
created with 4 control vertices have the same shape as Bezier curves of degree
3 as shown on the right.
Draw Splines | 283