From 16,000 feet a photographic plate could cover some of front line in sharp detail. In 1915 Lieutenant-Colonel JTC Moore-Brabrazon designed the first practical aerial camera. These semi-automatic cameras became a high priority for the Corps and photo-reconnaissance aircraft were soon operational in numbers with the RFC. The camera was usually fixed to the side of the fuselage, or operated through a hole in the floor. The increasing need for surveys of the western front and its approaches, made extensive aerial photography essential. Aerial photographs were exclusively used in compiling the British Army's highly detailed 1:10,000 scale maps introduced in mid-1915. Such were advances in aerial photography that the entire Somme Offensive of July–November 1916 was based on the RFC's air-shot photographs.