传统细分曲线由于只使用了局部信息来更新顶点位置,在控制顶点分布不均匀时曲率分布波动较大.为提高细分曲线质量,提出一类全局性的细分方法.将曲线的每一次细分分解成差分计算、插值、重建等一些简单的步骤;通过修改其中的重建步骤,将曲线重建的顶点放宽至所有控制顶点,配合扩大的模板和改进的插值以进一步改进曲线的几何质量.最后通过实验数据验证了此类全局性细分曲线在光滑性和曲率分布上的良好性质.
The quality of traditional subdivision curves are restricted by the local mask of subdivision schemes.Notice that a step of subdivision can be decomposed into a sequence of simple stages-calculating the difference,interpolation and reconstruction.A class of global subdivision curves is proposed by manipulating the reconstruction stage.Through a reconstruction involving all the control vertices,the subdivision turns to be global.An improvement on the smoothness and curvature distribution is proved then.Further improvement can be achieved by employing high-order difference and smoother interpolations.Experiments show that the curvature distribution improves under our new construction for subdivision curves.