I am confused by the description of OFFSETB in wiewshed analysis (ArcGIS 10.1).
The help documentation says:
The OFFSETB item indicates a vertical distance in surface units to be added to the z-value of each cell as it is considered for visibility.
Still, to me is rather obscure.
I understood that OFFSETA should be the value representing the height of the observer point: that is, if an observer is 2 meters high, and (s)he is on a spot 10 meters above sea level, the total elevation of the observer point will be 12m.
As to OFFSETB: is that the height of a target object? What this actually represents? Or is it the height (in the landscape) below which the viewshed is not calculated?