Use of Oblique Photography started early

Oblique aerial photography is so called when you take photos from an angle in order to get some details which cannot show if the photos are taken from exactly above the structure to be photographed. Two types of oblique photography soon evolved.  High angle oblique aerial photographs captured the apparent horizon. The low angle variety could not do that, the range being limited.

An aerial photographer always held discussions with clients to know what exactly was needed and the best way to obtain satisfying results.  He made absolutely sure of the scope of his task before boarding the aircraft. Consulting when you were airborne was just not the done in those days when cell phone was non-existent. . A perceptive aerial photographer like the ones with us now made it a point to photograph the target or target area from a wide variety of angles to show all possible access on the ground. Juxtaposed with the ground photos or vertical photographs and by comparison, you could   have a very clear idea of what exactly you were looking at. Unless specifically asked for, the normal practice had been and still is to supply 20 or so photographs. 

Why go for oblique photographs? When the helicopter is circling at the same exact height, a large area could be covered from the same distance. The old aerial photos  thus taken could provide accurate details of the locations. The interpreter had a wide scope of apprehending the details. Objects that could not have a three dimensional perspective in a vertical photographs could be accorded it, though in a limited way.  

Another advantage of oblique photography was the obstructions the clouds could pose. Vertical photography was hampered by the density of clouds rendering the photographs hazy-looking thereby making interpreting that much difficult.  In oblique photography, the angles enabled the camera to penetrate easily through the clouds and capture the view below faithfully to a large extent.


Fore more information : http://www.earticlesonline.com/Article/Capturing-Beauty-From-High-Above--Aerial-Photos---/1162993