1 识别轮廓
findcontours
https://blog.youkuaiyun.com/m0_37706703/article/details/81081352
轮廓及其各种特性
https://blog.youkuaiyun.com/kwame211/article/details/81000136
2 二值化
threshold:
https://blog.youkuaiyun.com/a19990412/article/details/81172426
3 轮廓的凸包和凹性检测
https://blog.youkuaiyun.com/zhangjunhit/article/details/102800108