Here again, as with vertical photographs, oblique
photographs can be made with photo-configured
aircraft or with a hand-held camera.
High-Oblique Photography
High-oblique photography is accomplished at a
camera angle that shows the horizon at about a
30-degree camera depression angle (fig. 4-4). It
resembles the view a pilot sees when approaching the
target. High-oblique photographs are useful in guiding
pilots toward a photographic target, a bombing target,
or a helicopter landing site. High-oblique photographs
are also used for orientation purposes because large
areas are covered. A high-oblique photograph is
particularly suitable for pictorial and illustrative
purposes because it provides a true perspective view of
land surfaces. It is easier for a person on the ground to
locate and identify objects in a high-oblique photograph
than in a low oblique or vertical photograph.
Low-Oblique Photography
Low-oblique photography does not show the
horizon (fig. 4-5). It is made with a camera depression
angle of about 60 degrees. A low-oblique photograph
covers a relatively small area. The subjects in a
low-oblique photograph look more familiar than in a
vertical photograph—as if you were viewing them from
the top of a tall building. A low-oblique photograph is
normally used for identification purposes, and for that
reason, a large image of the target is necessary.
You may at first come to the wrong conclusion,
because of their names, that high- and low-oblique
photographs are made from high and low altitudes,
respectively. This is not the case. The aircraft altitude
is not a determining factor in whether an oblique is
classified as high or low. Remember, the horizon is the
determining factor; high sky, low no. As a matter of
fact, most high-oblique photographs are made from a
Figure 4-4.—High-oblique aerial photographs.
4-3
