Application of Chebyshev II-Bernstein basis transformations to degree reduction of Bezier curves

作者：Lu Lizheng; Wang Guozhao

来源：Journal of Computational and Applied Mathematics, 2008, 221(1): 52-65.

DOI：10.1016/j.cam.2007.10.032

• Chebyshev polynomials of second kinds
• Basis trans format ions
• Bezier curves
• Degree reduction
• Endpoint continuity

A polynomial curve on vertical bar 0, 1 vertical bar can be expressed in terms of Bernstein polynomials and Chebyshev polynomials of the second kind. We derive the transformation matrices that map the Bernstein and Chebyshev coefficients into each other, and examine the stability of this linear map. In the p = l and infinity norms, the condition number of the Chebysbev-Bernstein transformation matrix grows at a significantly slower rate with it than in the power-Bernstein case, and the rate is very close (somewhat faster) to the Legendre-Bernstein case. Using the transformation matrices, we present a method for the best multi-degree reduction with respect to the root t - t(2)-weighted square norm for the unconstrained case, which is further developed to provide a good approximation to the best multi-degree reduction with constraints of endpoints continuity of orders r, s (r, s >= 0). This method has a quadratic complexity, and may be ill-conditioned when it is applied to the Curves of high degree. We estimate the posterior L-1-error bounds for degree reduction.

• 出版日期2008-11-1
• 单位浙江工商大学; 浙江大学