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Aerial photography

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Please improve this article or discuss the issue on the talk page. (September 2007)

The Georgian terrace of Royal Crescent (Bath, England) from a hot air balloon

Aerial photography is the taking of photographs of the ground from an elevated position. The term usually refers to images in which the camera is not supported by a ground-based structure. Cameras may be hand held or mounted, and photographs may be taken by a photographer, triggered remotely or triggered automatically. Platforms for aerial photography include fixed-wing aircraft, helicopters, balloons, blimps and dirigibles, rockets, kites, poles and parachutes.

Contents

1 History
2 Uses of imagery
3 Challenges
4 References
5 See also
6 External links

History

Aerial photography was first practiced by the French photographer and balloonist Nadar in 1858 over Paris, France. The use of aerial photography for military purposes was expanded during World War I by aviators such as Fred Zinn. One of the first notable battles was that of Neuve Chapelle

Uses of imagery

Reflection of a hot air balloon, partially obscured by a pier, an example of low altitude aerial photography

Aerial photography is used in cartography (particularly in photogrammetric surveys, which are often the basis for topographic maps), land-use planning, archaeology, movie production, environmental studies, surveillance, commercial advertising, conveyancing, and artistic projects. In the United States, aerial photographs are used in many Phase I Environmental Site Assessments for property analysis. Aerial photos are often processed by a GIS system.

Advances in radio controlled models has made it possible for model aircraft to conduct low-altitude aerial photography. This has benefited real-estate advertising, where commercial and residential properties are the photographic subject. Full-size, manned aircraft are prohibited from low flights above populated locations. Small scale model aircraft offer increased photographic access to these previously restricted areas. Miniature vehicles do not replace full size aircraft, as full size aircraft are capable of longer flight times, higher altitudes, and greater equipment payloads.

Because anything capable of being viewed from a public space is considered outside the realm of privacy in the United States, aerial photography may legally document features and occurrences on private property.

Challenges

Aerial photography includes challenges not present in non-aerial photography. Some of these include:

Perspective correction – Aerial photographs are often taken at an angle to the object being photographed. This means that the perspective of the photograph will be incorrect with near objects larger than far away objects. Perspective correction distorts the image so that equal sized objects in the real world have equal size in the photograph. See orthophoto.
Registration – Aerial photographs usually are mapped to the real world objects (streets, buildings, etc) being photographed. For example, an aerial photograph may be converted into a series of lines based on the roads contained in the photograph.
Stitching – To create an aerial photograph of a large area, multiple photographs must be taken. Stitching is joining those photographs together so that they form a single large photograph. This process creates “seamless” imagery.

References

^ History of Aerial Photography Professional Aerial Photographers Association (retrieved December 21 2007)
^ United States Federal Aviation Regulations FAR part 91 section 119(14CFR91.119)
^ California v. Ciraolo, 476 U.S. 206 (1986)

Aerial photography

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