Orthophotography combines the image characteristics of an aerial photograph with the geometric qualities of a map. Unlike a typical aerial photograph, distortions due to relief displacement (hills, stream valleys, buildings), camera lens, and aircraft attitude have been removed so that all ground features are shown in their correct ground positions. This makes a true image map possible and permits direct measurement of distances, areas, angles, and the detailed portions of ground features that are typically omitted or generalized on traditional maps.