sift

代码说明：

  SIFT特征（Scale-invariant feature transform，尺度不变特征转换)是一种电脑视觉的算法用来侦测与描述影像中的局部性特征，它在空间尺度中寻找极值点，并提取出其位置、尺度、旋转不变量(SIFT features (Scale-invariant feature transform, scale-invariant feature transform) is a computer vision algorithm to detect and describe the image characteristics of the locality, it scales in space to find extreme points, and extract its location , scale, rotation invariant)