(map aerial photographs) (2-8)
observers, then by _____________________________ parties who actually enter the area to obtain such data as
slope measurements, radii of curves, soil samples, bridge and tunnel data, etc. The three methods thus
___________________ provide maximum information.
Ordinary aerial photos contain inherent scale and image distortions, making distance and azimuth
measurements unreliable. Special grids must be constructed for point location.
Aerial photos cannot replace maps for ___________________________________ purposes, because they have
inherent __________________________ in scale and image.