说明：  道格拉斯-普克算法(Douglas–Peucker algorithm，亦称为拉默-道格拉斯-普克算法、迭代适应点算法、分裂与合并算法)是将曲线近似表示为一系列点，并减少点的数量的一种算法。它的优点是具有平移和旋转不变性，给定曲线与阈值后，抽样结果一定。
(Douglas Peucker algorithm is the curve approximated by a series of points, and reduce the number of points of an algorithm. It has the advantages of translation and rotation invariance, given the curve and the threshold, the sampling results must.)