Generates the height difference map. For each map pixel it calculates the average height delta to four nearby pixels. Could be useful for separating horizontal and vertical surfaces (to fill them with grass and cliff respectively).
To: the ending angle (in degrees) of the masking effect. Usually it's 90 (vertical), but if you want to create an inversed effect (from 0 to X) or mask only the slope of some particular degrees (from X to Y) it might be needed to set this value.
To (while From is 20): 20, 30, 40, 90