Number of input and output field

Number of input field	:	Two
Number of output field	:	One

This transformation function is used to calculate similarity of two SIFTDescriptors, using root-sift algorithm. The output is a number (interval [0.0, 1.0]) that represents similarity of them. A number value of 0.0 means that the two images are completely different whereas a return value of 1.0 means that all key points in the first image are matched with second image.