1.python opencv minAreaRect 生成最小外接矩形
https://blog.youkuaiyun.com/lanyuelvyun/article/details/76614872
2.python-opencv 的minAreaRect的详解
https://blog.youkuaiyun.com/qq_24237837/article/details/77850496
3.opencv 寻找最小矩形minAreaRect 的角度问题
https://blog.youkuaiyun.com/u010403272/article/details/78890410
4.Contour Features
https://docs.opencv.org/3.1.0/dd/d49/tutorial_py_contour_features.html