给出圆弧带参数的标准型有理三次Bézier表示的一种实用形式,讨论参数对内控制点、两内权因子及肩点的影响。详细分析该参数与圆弧非标准型二次Bézier表示下的权因子之间的内在关系,参数值的变化对应了一个有理线性参数变换。最后讨论了圆弧标准型有理三次Bézier表示的反算问题。

A practical way of representing circular arcs with standard-form cubic rational Bézier curves containing a parameter is presented. The parameter affecting the control points, weights and shoulder points is discussed. The inner relation between the parameter and the weights of representing circular arcs with nonstandard-form quadratic rational Bézier curves is analyzed in detail. Modifing the parameter value corresponds to a rational linear parameter transformation. Finally, we discuss the inverse calculation of the standard-form cubic rational Bézier representation of circular arcs.