Depending on different technical characteristics of the photographs can be made various classifications:
A) According to the degree of inclination or the angle of the shot it differs between:
Photographs oblique: In them, the axis of the camera points at a particular angle to the ground (greater than 3º). The aerial images are quite similar to those we can get with our camera from a passenger plane or a high point of a city. The horizon in the image cannot be appreciated. Aerial photographs with skyline or high oblique photographs, or simply panoramic when the angle is placed in the 45º and 90º, and you can see the horizon and the sky in the image.
Stereoscopic images or stereoscopic pairs: They are pairs of aerial photographs showing a common territory, and that from stereoscopes, devices that through a set of lenses and mirrors show the relief three-dimensional.
Vertical photographs: In which the lenses (or the axis) of the camera point vertically towards the surface producing a vision that resembles a plane of the ground. They are the most useful images even though a relatively small area is photographed. Vertical aerial photography presents a similar aspect to the plans, although with many more details. Usually, when talking about aerial photos, it refers to vertical aerial photographs.
B) According to the type of film, they are classified in:
Black and white photographs: those in which the image appears in white, black, and in different shades of gray. They are the cheapest and therefore the most used (or at least have been the most used for a long time). They are made with films of fine grain and great sensitivity, so they usually have a high resolution, and in them, the identification of the elements is made according to their shape, size, and color.
Photographs in color: allow to see all the elements with colors similar (but not equal) to those of the human vision. In recent years has increased its use, since although they are more expensive than black and white photographs, they offer many more details. In color images, reds and greens are easily distinguishable, while in black and white photographs these colors have the same shade of gray.
Color photographs are images with a high resolution that favor the work of photo interpretation and therefore have great utility in environmental, urban, geological studies, land uses. Color images are particularly useful in underwater research: Fluvial and marine bottom studies, differentiation of water bodies of different composition and temperature, freshwater outflows to the sea, submerged deltas, coastal currents, water pollution, tides, algae analysis, port studies, and sediment transport.
Thermal photographs: These are images in which the temperature of the elements that appear in the territory are shot.
C) According to the technique used aerial photographs are classified in:
Orto-photographs are images in which the conical projection (own of the vertical aerial photographs) has been transformed and has been transferred to a flat projection, much more efficient for the calculation of distance and the analysis of large surfaces.
Ortho-photomaps: Aerial photographs (usually ortho-photographs) in which some details of the image are marked or highlighted as the roads, the railways, the administrative limits.
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The author is a professional photographer based in Singapore. Mark Rin is an expert in photography and writes about aerial photography in Singapore.