To increase the accuracy of the heights obtained from a stereo pair, it is natural, first of all, to strive to ensure that one meter of height corresponds to the largest possible increment of the longitudinal parallax at a given scale of the photograph. Or, in other words, one should strive to increase the ratio of the increment (Ap) \ longitudinal parallax by 1 m to the segment (m)i, in the photograph corresponding to 1 m of horizontal extension on the ground. Let us designate this ratio as m. Thus, the value of the indicated ratio acquires a significant role in characterizing the accuracy of height determinations.
