So, I am reading a paper about ORB: An Efficient Alternative to SIFT or SURF and it happens to calculate the direction of corner from it center . According to Rosin the author of the paper;moments of a patch is given by
and the centroid is of the patch from the center is calculated using:
The direction of the patch is computed from
My question is what are these value of p
and q
and why is it out there?