Size winSize = Size(5,5);
Size zerozone = Size(-1,-1);
TermCriteria tc = TermCriteria(TermCriteria::EPS + TermCriteria::MAX_ITER, 40, 0.001);
cornerSubPix(img_gray1, vec_points, winSize, zerozone, tc);
原文：https://www.cnblogs.com/herd/p/9742018.html