基于两控制点的Dr.Bridge抛物线拟合方向辨识

Identification of Parabola Fitting Direction by Two Controlling Points of Dr. Bridge

提出在Dr.Bridge建模中利用直线快速编辑器准确辨识抛物线拟合方向的新方法.通过考查二次抛物线在单调区间内的凸凹性,确定基于两控制点抛物线可能出现的4种性态.在此基础上,引入表征抛物线单调性及凸凹性的两套符号,给出了基于两控制点抛物线拟合方向的判定方法,拓展了Dr.Bridge直线快速编辑器由两控制点准确拟合抛物线的新途径.无论由两控制点还是由三控制点进行抛物线拟合,该判定方法均能适用.本文方法操作简捷,易于程序实现.

A new method is presented to determine the fitting direction while using Dr.Bridge′s linear ed-itor to model various parabolas in this paper.By considering convex-concave property at monotone inter-val of a quadratic curve, four different parabola shapes with two controlling points fitted, are provided. Based on the method, two sets of symbols are introduced to describe the monotonicity and convex-concave property of parabola.And the identification of parabola fitting direction is presented, which explores a new way to fit a parabola by two controlling points when linear editor of Dr.Bridge is used.The presented method is suitable for determining the parabola fitting direction whether parabola is fitted by two or by three controlling points.The method is illustrated by its simplicity and convenience, and efficient for pro-gram realization, which greatly promotes the modeling efficiency.