The two major fields of application of aerial photography are “Aerial Photogrammetry” and “Photo Interpretation”. Photogrammetry mainly involves obtaining reliable measurements from photographs, wheres Photo interpretation, as the name implies involves recognising and identifying photographic images and judging their significance. In fact, Photogrammetry includes photo interpretation also.
The earliest applications of Aerial Photogrammetry were in topographic mapping, and today that use is still the most common of photogrammetric activities. In addition to topographic mapping, many other special purpose maps are also prepared photogrammetrically. These maps vary in scale from large to small and are used in planning and designing highways, railroads, rapid transit systems, bridges, pipelines, aqueducts, transmission lines, hydroelectric dams, flood control structures, river and harbour improvements, urban renewal refocus, etc. Non-engineering applications include the preparation of soil maps, Aerial Photogrammetry is used in the fields of astronomy, architecture, archaeology, geomorphology, oceanography, hydrology and water resources, conservation, ecology and mineralogy. Stereoscopic photography literally enables the outdoors to be brought into the comfortable confines of the laboratory or office for viewing and study in three dimensions. It would be difficult to cover all the many situations in which measurement problems. Photogrammetry, although still a relatively new science, has already contributed substantially to engineering and non-engineering feels alike. New applications appear to be bounded only by our imagination, and the science should continue to grow in the future.
Types of Aerial Photography
Aerial photography is classified into two major categories. They are
1. Vertical photography
2. Oblique photography
a) Low oblique photography
b) High oblique photography
Photography taken from any air borne vehicle (aerial photography) with camera axis vertical or nearly vertical is known as “Vertical Photography”. Photography taken with the camera axis intentionally deviated from the vertical is called a high oblique and if not a low oblique. In other words, the optical axis of the camera is nearer to the vertical in the case of a low oblique and nearer to the horizontal in the case of a high oblique photograph.