A piecewise quadratic trigonometric rational spline curve is presented and analyzed in this paper. Each curve segment is constructed by using three consecutive control points. The spline curves can be C3 continuous for uniform knot vector and C2 continuous for non-uniform knot vector. A local shape parameter is used in the spline curves. As the increase of the value of shape parameter, the curves approach to the edge of the control polygon.
Xuli Han, Xuli Han,
"Piecewise quadratic trigonometric rational spline curves", Proc. SPIE 4875, Second International Conference on Image and Graphics, (31 July 2002); doi: 10.1117/12.477101; https://doi.org/10.1117/12.477101