一种比sift效果更好的算法，可实现图像在几乎任意仿射变化下的特征提取，而且特征点比SIFT多，是09年最新的算法-asift, full name is the affine scale-invariant feature transform, that is, of scale-invariant features of affine transform, is used to extract more of the characteristics of affine distortion