High-Oblique Photography

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