2012

Table Of Contents
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.
You can close a spline so that the start point and end point are coincident
and tangent. By default, closed splines are mathematically periodic, meaning
that they have the smoothest (C2) continuity at the point of closure.
In the example, both splines are closed, and the point of closure is marked
with a dot. The result of setting the SPLPERIODIC system variable to periodic
is shown on the left, while the result of the legacy setting is shown on the
right.
214 | Chapter 6 Create and Modify Objects