Aerial photography

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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. Platforms for aerial photography include fixed-wing aircraft, helicopters, multirotor Unmanned Aircraft Systems (UAS), balloons, blimps and dirigibles, rockets, kites, parachutes, stand-alone telescoping and vehicle mounted poles. Mounted cameras may be triggered remotely or automatically; hand-held photographs may be taken by a photographer.

Aerial photography should not be confused with Air-to-Air Photography, where one-or-more aircraft are used as Chase planes that "chase" and photograph other aircraft in flight.

History[edit]

Early History[edit]

Honoré Daumier, "Nadar élevant la Photographie à la hauteur de l'Art" (Nadar elevating Photography to Art), published in Le Boulevard, May 25, 1862.

Aerial photography was first practiced by the French photographer and balloonist Gaspard-Félix Tournachon, known as "Nadar", in 1858 over Paris, France.[1] However, the photographs he produced no longer exist and therefore the earliest surviving aerial photograph is titled 'Boston, as the Eagle and the Wild Goose See It.' Taken by James Wallace Black and Samuel Archer King on October 13, 1860, it depicts Boston from a height of 630m.[2][3]

Antique postcard using kite photo technique.

Kite aerial photography was pioneered by British meteorologist E.D. Archibald in 1882. He used an explosive charge on a timer to take photographs from the air.[4] Frenchman Arthur Batut began using kites for photography in 1888, and wrote a book on his methods in 1890.[5][6] Samuel Franklin Cody developed his advanced 'Man-lifter War Kite' and succeeded in interesting the British War Office with its capabilities.

The first use of a motion picture camera mounted to a heavier-than-air aircraft took place on April 24, 1909 over Rome in the 3:28 silent film short, Wilbur Wright und seine Flugmaschine.

World War I[edit]

Giza pyramid complex, photographed from Eduard Spelterini's balloon on November 21, 1904

The use of aerial photography rapidly matured during the war, as reconnaissance aircraft were outfitted with cameras to record enemy movements and defences. At the start of the conflict, the usefulness of aerial photography was not fully appreciated, with reconnaissance being accomplished with map sketching from the air.

Germany adopted the first aerial camera, a Görz, in 1913. French Military Aviation began the war with several squadrons of Bleriot observation planes, equipped with cameras for reconnaissance. The French Army developed procedures for getting prints into the hands of field commanders in record time.

Frederick Charles Victor Laws initiated an aerial photography capability in 1912 for the 1st Airship Squadron and he began experimenting with aerial photographs from the British dirigible airship Beta. He discovered that vertical photos taken with 60% overlap could be used to create a stereoscopic effect when viewed in a stereoscope, thus creating a perception of depth that could aid in cartography and in intelligence derived from aerial images. The dirigibles were eventually allocated to the Royal Navy, so Laws formed the first aerial reconnaissance unit of fixed-wing aircraft; this became No. 3 Squadron RAF. The Royal Flying Corps recon pilots began to use cameras for recording their observations in 1914 and by the Battle of Neuve Chapelle in 1915, the entire system of German trenches was being photographed.[7] In 1916 the Austro-Hungarian Monarchy made vertical camera axis aerial photos above Italy for map-making.

A German observation plane, the Rumpler Taube.

The first purpose-built and practical aerial camera was invented by Captain John Moore-Brabazon in 1915 with the help of the Thornton-Pickard company, greatly enhancing the efficiency of aerial photography. The camera was inserted into the floor of the aircraft and could be triggered by the pilot at intervals. Moore-Brabazon also pioneered the incorporation of stereoscopic techniques into aerial photography, allowing the height of objects on the landscape to be discerned by comparing photographs taken at different angles.[8][9]

By the end of the war, aerial cameras had dramatically increased in size and focal power and were used increasingly frequently as they proved their pivotal military worth; by 1918 both sides were photographing the entire front twice a day and had taken over half a million photos since the beginning of the conflict. In January 1918, General Allenby used five Australian pilots from No. 1 Squadron AFC to photograph a 624 square miles (1,620 km2) area in Palestine as an aid to correcting and improving maps of the Turkish front. This was a pioneering use of aerial photography as an aid for cartography. Lieutenants Leonard Taplin, Allan Runciman Brown, H. L. Fraser, Edward Patrick Kenny, and L. W. Rogers photographed a block of land stretching from the Turkish front lines 32 miles (51 km) deep into their rear areas. Beginning 5 January, they flew with a fighter escort to ward off enemy fighters. Using Royal Aircraft Factory BE.12 and Martinsyde airplanes, they not only overcame enemy air attacks, but also bucked 65 mile per hour winds, antiaircraft fire, and malfunctioning equipment to complete their task circa 19 January 1918.[10]

Commercial Aerial Photography[edit]

The first commercial aerial photography company in the UK was Aerofilms Ltd, founded by World War I veterans Francis Wills and Claude Graham White in 1919. The company soon expanded into a business with major contracts in Africa and Asia as well as in the UK. Operations began from the Stag Lane Aerodrome at Edgware, using the aircraft of the London Flying School. Subsequently the Aircraft Manufacturing Company (later the De Havilland Aircraft Company), hired an Airco DH.9 along with pilot entrepreneur Alan Cobham.[11]

New York City 1930, aerial photograph of Fairchild Aerial Surveys Inc.

From 1921, Aerofilms carried out vertical photography for survey and mapping purposes. During the 1930s, the company pioneered the science of photogrammetry (mapping from aerial photographs), with the Ordnance Survey amongst the company's clients.[12]

Another successful pioneer of the commercial use of aerial photography was the American Sherman Fairchild who started his own aircraft firm Fairchild Aircraft to develop and build specialized aircraft for high altitude aerial survey missions.[13] One Fairchild aerial survey aircraft in 1935 carried unit that combined two synchronized cameras, and each camera having five six inch lenses with a ten inch lenses and took photos from 23,000 feet. Each photo covered two hundred and twenty five square miles. One of its first government contracts was an aerial survey of New Mexico to study soil erosion.[14] A year later, Fairchild introduced a better high altitude camera with nine-lens in one unit that could take a photo of 600 square miles with each exposure from 30,000 feet.[15]

World War II[edit]

Sidney Cotton's Lockheed 12A, in which he made a high-speed reconnaissance flight in 1940.

In 1939 Sidney Cotton and Flying Officer Maurice Longbottom of the RAF were among the first to suggest that airborne reconnaissance may be a task better suited to fast, small aircraft which would use their speed and high service ceiling to avoid detection and interception. Although this seems obvious now, with modern reconnaissance tasks performed by fast, high flying aircraft, at the time it was radical thinking.[citation needed]

They proposed the use of Spitfires with their armament and radios removed and replaced with extra fuel and cameras. This led to the development of the Spitfire PR variants. Spitfires proved to be extremely successful in their reconnaissance role and there were many variants built specifically for that purpose. They served initially with what later became No. 1 Photographic Reconnaissance Unit (PRU). In 1928, the RAF developed an electric heating system for the aerial camera. This allowed reconnaissance aircraft to take pictures from very high altitudes without the camera parts freezing.[16] Based at RAF Medmenham, the collection and interpretation of such photographs became a considerable enterprise.[17]

Cotton's aerial photographs were far ahead of their time. Together with other members of the 1 PRU, he pioneered the techniques of high-altitude, high-speed stereoscopic photography that were instrumental in revealing the locations of many crucial military and intelligence targets. According to R.V. Jones, photographs were used to establish the size and the characteristic launching mechanisms for both the V-1 flying bomb and the V-2 rocket. Cotton also worked on ideas such as a prototype specialist reconnaissance aircraft and further refinements of photographic equipment. At the peak, the British flew over 100 reconnaissance flights a day, yielding 50,000 images per day to interpret. Similar efforts were taken by other countries.

Uses[edit]

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

Aerial photography is used in cartography[18] (particularly in photogrammetric surveys, which are often the basis for topographic maps), land-use planning,[18] archaeology,[18] 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.

Platforms[edit]

Radio-controlled model aircraft[edit]

Advances in radio controlled models have 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.[19] 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. They are, however, useful in any situation in which a full-scale aircraft would be dangerous to operate. Examples would include the inspection of transformers atop power transmission lines and slow, low-level flight over agricultural fields, both of which can be accomplished by a large-scale radio controlled helicopter. Professional-grade, gyroscopically stabilized camera platforms are available for use under such a model; a large model helicopter with a 26cc gasoline engine can hoist a payload of approximately seven kilograms (15 lbs).

Fogo island aerial shot taken from an Airbus cockpit by the pilot

Recent (2006) FAA regulations grounding all commercial RC model flights have been upgraded to require formal FAA certification before permission to fly at any altitude in USA.

In Australia Civil Aviation Safety Regulation 101 (CASR 101)[20] allows for commercial use of radio control aircraft. Under these regulations radio controlled unmanned aircraft for commercial are referred to as Unmanned Aircraft Systems (UAS), where as radio controlled aircraft for recreational purposes are referred to as model aircraft. Under CASR 101, businesses/persons operating radio controlled aircraft commercially are required to hold an Operator Certificate, just like manned aircraft operators. Pilots of radio controlled aircraft operating commercially are also required to be licenced by the Civil Aviation Safety Authority (CASA).[21] Whilst a small UAS and model aircraft may actually be identical, unlike model aircraft, a UAS may enter controlled airspace with approval, and operate within close proximity to an aerodrome.

Due to a number of illegal operators in Australia making false claims of being approved, CASA maintains and publishes a list of approved UAS operators[22]

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.[23]

Types[edit]

Oblique[edit]

Photographs taken at an angle are called oblique photographs. If they are taken from a low angle earth surface–aircraft, they are called low oblique and photographs taken from a high angle are called high or steep oblique.[24]

Vertical[edit]

Vertical photographs are taken straight down.[25][dead link] They are mainly used in photogrammetry and image interpretation. Pictures that will be used in photogrammetry are traditionally taken with special large format cameras with calibrated and documented geometric properties.

Combinations[edit]

Aerial photographs are often combined. Depending on their purpose it can be done in several ways, of which a few are listed below.

  • Panoramas can be made by stitching several photographs taken with one hand held camera.
  • In pictometry five rigidly mounted cameras provide one vertical and four low oblique pictures that can be used together.
  • In some digital cameras for aerial photogrammetry images from several imaging elements, sometimes with separate lenses, are geometrically corrected and combined to one image in the camera.

Orthophotos[edit]

Vertical photographs are often used to create orthophotos, alternatively known as orthophotomaps, photographs which have been geometrically "corrected" so as to be usable as a map. In other words, an orthophoto is a simulation of a photograph taken from an infinite distance, looking straight down to nadir. Perspective must obviously be removed, but variations in terrain should also be corrected for. Multiple geometric transformations are applied to the image, depending on the perspective and terrain corrections required on a particular part of the image.

Orthophotos are commonly used in geographic information systems, such as are used by mapping agencies (e.g. Ordnance Survey) to create maps. Once the images have been aligned, or "registered", with known real-world coordinates, they can be widely deployed.

Large sets of orthophotos, typically derived from multiple sources and divided into "tiles" (each typically 256 x 256 pixels in size), are widely used in online map systems such as Google Maps. OpenStreetMap offers the use of similar orthophotos for deriving new map data. Google Earth overlays orthophotos or satellite imagery onto a digital elevation model to simulate 3D landscapes.

Aerial video[edit]

With advancements in video technology, aerial video is becoming more popular.[26] Orthogonal video is shot from aircraft mapping pipelines, crop fields, and other points of interest. Using GPS, video may be embedded with meta data and later synced with a video mapping program.

This "Spatial Multimedia" is the timely union of digital media including still photography, motion video, stereo, panoramic imagery sets, immersive media constructs, audio, and other data with location and date-time information from the GPS and other location designs.

Aerial videos are emerging Spatial Multimedia which can be used for scene understanding and object tracking. The input video is captured by low flying aerial platforms and typically consists of strong parallax from non-ground-plane structures. The integration of digital video, global positioning systems (GPS) and automated image processing will improve the accuracy and cost-effectiveness of data collection and reduction. Several different aerial platforms are under investigation for the data collection.

See also[edit]

References[edit]

  1. ^ History of Aerial Photography Professional Aerial Photographers Association (retrieved December 21, 2007)
  2. ^ Ron Graham and Roger E. Read, Manual of Aerial Photography, London and Boston, Focal Press, ISBN 0-240-51229-4
  3. ^ Staff writer (April 3, 2013). "This Picture of Boston, Circa 1860, Is the World’s Oldest Surviving Aerial Photo". Smithsonian Magazine. Retrieved April 17, 2013. 
  4. ^ Archibald, Douglas (1897). "The Story of the Earth's Atmosphere". p. 174. Retrieved 2011-04-16.
  5. ^ Benton, Cris (June 25, 2010). "The First Kite Photographs". arch.ced.berkeley.edu. Retrieved 2011-04-16. 
  6. ^ "Arthur Batut Museum" (in French). Retrieved 2008-01-08. 
  7. ^ "A Brief History of Aerial Photography". 
  8. ^ "Royal Flying Corps Founded". History Today. 
  9. ^ Marshall Cavendish Corporation (2003). How It Works: Science and Technology. Marshall Cavendish. p. 33. 
  10. ^ "Lieutenant Leonard T.E. Taplin, D.F.C". Southsearepublic.org. Retrieved 2013-01-24. 
  11. ^ http://www.screenonline.org.uk/people/id/585816/
  12. ^ "Municipal Air Surveys. Contracts From Doncaster And Birkenhead". The Times (issue:44229,column:E). Gale:The Times digital archive 1785–1985. 25 March 1926. p. 11. Retrieved 30 August 2012.  (subscription required)
  13. ^ The Complete Encyclopedia of World Aircraft. 1997. p. 382. ISBN 0-7607-0592-5. 
  14. ^ "Wide Area Is Mapped From Air By Giant Ten Lens Camera" Popular Mechanics, October 1935 editors have stated Fairchild Aircraft in hand written comment to left of archived article
  15. ^ "Nine Lens Aerial Camera Films 600 Square Miles" ''Popular Mechanics'', April 1936. Books.google.com. Retrieved 2013-01-24. 
  16. ^ "Photography Before Edgerton". 
  17. ^ Cotton, Sidney (1969). Aviator Extraordinary: The Sidney Cotton Story. Chatto & Windus. p. 169. ISBN 0-7011-1334-0. 
  18. ^ a b c "Aerial Photography and Remote Sensing". University of Colorado Boulder. 2011. Retrieved March 25, 2011. 
  19. ^ United States Federal Aviation Regulations FAR part 91 section 119(14CFR91.119)
  20. ^ "Civil Aviation Safety Regulations 1998". Australian Civil Aviation Safety Authority. 2002-12-19. Retrieved 2013-01-24. 
  21. ^ "Civil Aviation Safety Authority". Australian Civil Aviation Safety Authority. 2002-12-19. Retrieved 2013-01-24. 
  22. ^ "List of UAS Operator Certificate Holders". Australian Civil Aviation Safety Authority. Retrieved 2013-01-24. 
  23. ^ California v. Ciraolo, 476 U.S. 206 (1986)
  24. ^ "Lecture 6.1: Classification of Photographs". The Remote Sensing Core Curriculum. University of Maryland, Baltimore County. 1999. Retrieved 2011-03-25. 
  25. ^ Short, Nicholas (2010-04-28). "Elements of Aerial Photography". Remote Sensing Tutorial Page 10-1. NASA. Retrieved 2011-03-25. [dead link]
  26. ^ https://vimeo.com/68813290%7C Aerial Video of approach and landing at John Wayne Airport in a Cessna 172

Further reading[edit]

  • Price, Alfred (2003). Targeting the Reich: Allied Photographic Reconnaissance over Europe, 1939-1945. [S.l.]: Military Book Club. N.B.: First published 2003 by Greenhill Books, London. ISBN 0-7394-3496=9

External links[edit]