在各种图形中，通过提取点的凹凸部分来鉴别曲线的特征，本节代码利用曲率关系分别提取凹点的个数，判断曲线的弯曲-In a variety of graphics, through the extraction point to identify curves convex-concave part of the characteristics of the code used in this section were extracted from concave curvature of the r

算法：从任意曲线中提取Bezier曲线的关键点，这样可以对曲线形状进行任意平滑控制。-Algorithm: to extract from any curves the critical point Bezier curves, which can be arbitrary smooth shape of the curve control.

提取USF文件中的数据绘制瞬变电磁多测道曲线图(Extract the data from the USF file, draw the transient electromagnetic multiple plot curve diagram)