ASIFT算法就是为了解决SIFT、ORB、SURF等特征描述算子倾斜匹配的问题。上面的这些算法可以很好的应对尺度、旋转情况下的匹配，但是对于倾斜影像的特征点匹配只能提取很少量的特征，所以作者提出ASIFT来解决这个问题。(If a physical object has a smooth or piecewise smooth boundary, its images obtained by cameras
in varying positions undergo smooth apparent deformations. These deformations are locally
well approximated by affine transforms of the image plane. In consequence the solid object
recognition problem has often been led back to the computation of affine invariant image local
features. The similarity invariance (invariance to translation, rotation, and zoom) is dealt with
rigorously by the SIFT method The method illustrated and demonstrated in this work, AffineSIFT (ASIFT), simulates a set of sample views of the initial images, obtainable by varying the
two camera axis orientation parameters, namely the latitude and the longitude angles, which
are not treated by the SIFT method. Then it applies the SIFT method itself to all images thus
generated. Thus, ASIFT covers effectively all six parameters of the affine transform.)