In practice, since there are image rotations, the image pair is not
taken from the same height, the overlap percentage is irregular
across the image, the initial estimation for the possible matching
point could be away from the position corresponding to the average
flight height, and so on, the result from the above equation is usually
too small. We recommend increasing the calculated result from the
above equation with a factor of one and one-half to two times the
search window size X. For example, a calculated window size of 7
would be increased to 11 or 15.