Introduction
Aerial photography is broadly defined as any photography of the ground that takes place from an elevated position. From a technical point of view, the camera taking the photographs should not be attached to any ground-based structure. Aircraft and helicopters are most commonly used for aerial photography but rockets, blimps, hot-air balloons, kites and parachutes can also be used. Today, aerial photography is widely used in real estate and property development. Aerial photographs allow developers to get a bird's eye view of the terrain and effectively map out real estate developments. Many topographical maps were created using aerial photographs combined with land surveys. Powerful cameras can zoom in on specific areas that may be more inaccessible over land.
Definition of Aerial photography
v A photograph of the Earth’s surface taken with a camera that is mounted on the airplane.
v Photographs of a part of the earth's surface taken by a camera mounted in an aircraft for mapping purposes. This usually consists of a series of overlapping vertical photos taken in strips which can form the basis for mapping.
v Photos taken from airplanes to assist growers to determine variations within an area of interest such as a field.
Types of aerial photographs
Oblique photographs
Photographs taken at an angle are called oblique photographs. If they are taken almost straight down are sometimes called low oblique and photographs taken from a shallow angle are called high oblique.
Vertical photographs
Vertical photographs are taken straight down. 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
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.
Pteryx UAV, a civilian UAV for aerial photography and photomapping with roll-stabilised camera head
Vertical photographs are often used to create orthophotos, 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 from 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.
History of Aerial Photography
1885 | 1934-1935 | 1936-1952 | 1965-1995 | Other resources
In 1935, a man needed binoculars to view the completed mosaic aerial survey of the entire state. Source: Connecticut State Archives RG056, Connecticut Tercentenary Commission, 1929-1936, “Photographs.”
1885
In September and October 1885 Alfred E. Moore and John G. Doughty flew over Connecticut in a hot air balloon. Mr. Doughty was invited in order to attempt to get photographs. Each has written about his experiences.
Mr. Doughty describes his great fear of leaving the earth and his relief, every time the first ascension was delayed. But, he says, “… the paralyzing fear felt at starting was entirely lost before we had risen one hundred feet…” (Century v.32:no.5 1886:Sept. p.681), Because the first ascension was delayed till 5:00, the photographs he took that September day did not turn out satisfactorily. After constructing new equipment to support the camera, they ascended in October and took the pictures available to us now.
American aeronauts John G. Doughty and Alfred E. Moore and 2 other men seated inside balloon. c1886. Source: Library of Congress. Prints and Photographs Division
There are balloon aerial photographs by John Doughty, from the collection of the Connecticut Historical Society, online at Connecticut History Online via the University of Connecticut Libraries. Find related photographs with the search term “Balloon.”
More related to these flights:
“Amateur ballooning” by Alfred E. Moore. In The Century : a popular quarterly. V.32: no. 5 1886:Sept. p.670-679. From Cornell University Library, Making of America
“Balloon experiences of a timid photographer” by John G. Doughty. In The Century : a popular quarterly. v.32:no. 5 1886:Sept. p.679-694. New York, Century Company. From Cornell University Library, Making of America.
Includes a photograph of Hartford at p.691 with caption “Hartford from three-quarters of a mile high, looking south.”
Includes a photograph at p. 692 with caption: “View of the earth from an altitude of one mile” identified elsewhere as “Photo of Bloomfield from an altitude of one mile, taken from a balloon by John G. Doughty, 1885; … The farm of S.B. Pinney appears in the center.” (Identification appears in the print version of “Written in stone : how Connecticut’s landscape shapes our lives” by Collin Harty in Hog River Journal v.4:no.3 Summer 2006, p. 38-43.)
The Library of Congress has some of the John G. Doughty photographs online as well. Click on the link, then “Check for online items from this group.” Includes 4 photographs, including the Winsted photograph. Aerial views of Connecticut taken from balloon in an experiment to take photographs at altitudes up to ca. 6000 feet John G. Doughty, photographer, 1885, c1886. From Library of Congress Prints and Photographs Division Washington, D.C. 20540 USA.
1934-1935
The 1934 Aerial Survey Project: a Tool for State Planning
Governor Wilbur L. Cross recommended an aerial survey of the entire state of Connecticut to the State Planning Board in 1933. The governor and the board saw such a survey as an essential tool in planning for the state’s future. Dr. Charles G. Chakerian, director of the Board, said "The Water, Tax, Health, Highway and other departments had wanted one for years." (Hartford Daily Courant Mar. 31, 1935)
The survey would be the first government sponsored aerial survey of an entire state. (The Institute of Geographical Exploration at Harvard University conducted an earlier survey of Massachusetts, the first of an entire state. These photographs can not be found today.)
Fairchild Aerial Surveys, Inc. of New York City, an innovator in aerial photography and aviation, conducted the aerial photography for Connecticut’s survey. The result was thousands of individual photographs, which were pieced together to make a massive mosaic view of the state.
The State Planning Board
Governor Wilbur L. Cross. Source: Connecticut State Library
Governor Cross organized the State Planning Board in late 1933 and the first board statement was issued on January 8, 1934. The Planning Board was originally composed of:
Civil works planning was a national initiative through the National Planning Board of the Federal Emergency Administration. The effort was to identify worthwhile public works projects that could be funded with federal money. The National Board delegated to a regional board for New Jersey, New York and Connecticut. The state board reported to both. The money for Connecticut’s planning board came through the Civil Works Administration and the Public Works Administration.
The purpose of the planning board was to coordinate and integrate information pertaining to growth and development of the State. They collected information, data and maps from across departmental lines and made the information available to all. There were several projects initiated by the board relating to water quality, forests, highways, population demographics and zoning. An aerial map of the State was considered “the most essential single step for our state-wide data.” (Connecticut State Planning Board, Statement #9, April 4, 1934. CSL call number: ConnDoc P693 st) The aerial survey would give valuable information to many state departments.
1934 Aerial Photography
"Two men in a cabin plane circled around in a cloudless sky. They flew, at 100 miles an hour, up the state. Every 25 seconds the photographer took a picture of three and one quarter miles." (Hartford Daily Courant Mar. 31, 1935)
The planning for the aerial survey had already begun before January 1934. Fairchild Aerial Surveys, Inc. was chosen to conduct the photography and photographing of a photo mosaic. Fairchild was perhaps the only company capable of doing a survey of a complete state at this time. The company was named after its founder, Sherman M. Fairchild. He was a restless scientific genius that came from a wealthy family. In consequence, he had means to form companies around his inventions. After the First World War, he formed a company to manufacture his revolutionary aerial survey camera. Fairchild Aerial Surveys, Inc. was formed in 1922 to exploit the innovations of the camera. He then formed a company to build airplanes with enclosed cabins and single wings to expedite aerial surveys.
In the 1920s, the Fairchild Aerial Survey company “constantly lobbied Governor John Trumbull to contract for a survey. After all, Trumbull could be called, ‘The Aviation Governor,’ because … he was an active pilot. When Lindberg came to Hartford … after crossing the Atlantic, Trumbull flew his plane in to Brainard Airport to meet him” (memo from State Archivist Mark Jones to State Librarian, Ken Wiggin, dated 6/25/99). But at that time, no one state agency could pay for an aerial survey. The project waited till the State Planning Board coordinated the effort.
Sherman M. Fairchild 1929. Source: Aerofiles.com
Four airplanes did the aerial photography for the Connecticut survey in March and April 1934. The early spring months were chosen so as to be free of snow cover yet be before the sprouting of leaves on trees. Fairchild owned three of the airplanes, probably Fairchild manufactured FC-2 cabin airplanes. It had a heated, enclosed cabin so that pilot and photographer could endure long hours in the air. It was a monoplane with the wing extending from the top of the airplane to have an unobstructed downward view. The wings also folded for transport by railroad to survey locations. The fourth airplane belonged to the Connecticut National Guard, 43rd Air Division, 118th Observation Squadron. This was a Douglas O-38E two-seat, open cockpit observation biplane that was standard with the Air Corps at the time.
Douglas O-38. Source: Aerofiles.com
The pilots for the photography were:
The photographers, all from Fairchild, were:
The camera used was a Fairchild K-3 aerial survey camera with a 9.5” focal length, F4.5 lens and a haze-reducing filter. The camera was mounted on a frame and had an electric motor advance and a timing device to automatically shoot pictures. The view-finder had two inked lines to aim for current exposure and overlap of image. The film was 9 inches wide and 75 feet long rolled in canisters. There were 100 exposures per roll. The exposures were 7.5” x 9” each. The scale was 1”:1,200’. (The prints in the collection of the State Library have the same scale.)
The survey fights were flown at 11,400 feet, as level as the pilot could fly. The speed of the airplane was kept at 100 miles per hour. The photography was taken at vertical (90 degrees.) The exposures were taken at a rate to have a 50% overlap. That is, each photograph would have half of the previous exposure and half of the subsequent exposure. Photographs were taken in flight lines of 16 to 20 miles that were plotted from topographic maps. The air crews could take as many as four rolls of film in a day of filming.
The aerial photography was done on good weather days in March and April 1934. Optimum time of day for photography was from 10 AM until 2 PM. A total of 153 flying hours were required for the four airplanes to cover the 5,004 square miles of the state.
There were 10,484 exposures made in the state survey of which many were unusable because of missed orientation, clouds or reflections. The film was shipped to Fairchild Aerial Surveys Inc. for developing and printing. At least two sets of prints were shipped back to Hartford: one to the Connecticut State Library and one to be used in the creation of the mosaic map. Copy photographs were requested from the State Library almost immediately after arrival. Copy photographs were ordered from Fairchild, who housed the negatives.
Fairchild also provided index sheets to the photographs. The 33 index sheets are reproductions of the 1895 U.S. Geological Survey topographic maps with boxes inked in to locate particular photographs. The photograph number was printed inside the box. A photograph number in a circle identified photographs not printed. Approximately every other photograph was indexed perhaps for reasons of space on the sheets. The State Library enlarged the index sheets to the scale of the U.S. Geological Survey topographic maps.
Detail of Index Sheet 031. Source: Connecticut State Archives, RG 089:11a. Aerial Survey of Connecticut 1934 Index Sheet 031.
The boxes overlap one another and are each a little skewed. If you were holding a photograph, the top edge indicates in a general way where north is but the box on the index sheet shows that the photograph should be tilted a little up on one side or the other to represent its true relationship to the points of the compass.
1935 Mosaic Map
In 1935, employees of the Connecticut National Guard and the State Highway Department pieced the 7" x 9" photographs together like a jigsaw puzzle. The resulting mosaic, one very large picture of the entire state, was photographed and divided into 24" x 29" inch panels for ease of use.
The project to create a mosaic map from the thousands of aerial photographs was centered at Brainard Field airfield. The work took place in the assembly room of the Connecticut National Guard, 43rd Air Division, 118th Observation Squadron. Heading the project was William A. Duncanson, a supervisor from the state Highway Department. Seven to eight men were employed in assembling the mosaic. Some of the workers were from the ranks of the 118th Observation Squadron:
Sgt. Charles E. Gummer, working on the mosaic map. Source: Hartford daily courant, Mar. 31, 1935 p.D3.
The process of assembling the photo-mosaic began with matching, orienting and lining up photographs from flight lines according to topographic maps. The topographic maps were the same types used in orienting the airplanes during photography; the Connecticut 1890 Era 15-min Topographic Maps, 1:62,500, 1928 revision. The photographs were placed on wooden boards, about 5 feet by 7 feet. The photos were then painstakingly matched, cut to form an invisible seam and glued to the board with gum Arabic. Sometimes the photographs were soaked in water and slightly stretched to match adjoining photographs. The 24 completed boards, when assembled, made a 31 feet by 42 feet giant map of the state of Connecticut. A photograph of the completed mosaic illustrates the head of this article.
The mosaic panel boards were shipped to the Fairchild offices in New York in special cases and copy photographed onto a 14” x 17” negative. The mosaic panels were then copy photographed in nine sections relating to 5 degrees of latitude and longitude. Two hundred thirty-nine 24” x 28” mosaic panels were made from the resulting 11” x 14” negatives.
More related to the 1934 flight:
1936-1952
Aerial photographs were taken of the affected areas after the hurricanes of 1936, 1938 and the floods of 1955.
The 118th Photographic Section of the U.S. Army Air Corps flew over the hurricane and flood damaged areas of Connecticut and Rhode Island on Sept. 23-24, 1938.
There are photographs from 1938-1970 taken for Department of Transportation projects. Various state agencies had seen the importance of aerial photography and had been seeking the funding for additional statewide surveys since 1947. But there was no statewide aerial survey after 1934, until the U.S. Department of Agriculture conducted a survey in 1951 and 1952.
The State Library has the photographs from 1951-1952 and partial flights as mentioned above. Find out how to view the prints at the Research Guide to Aerial Photographs at the Connecticut State Library
1965 to 1995
Commissioner Newman E. Argraves of the Connecticut Highway Department testified to a committee of the state legislature in 1955 about the importance of aerial photography to the planning of highways. He said that without aerial photography the time lag between data gathering and map production was so great that industry, commerce and housing frequently encroached on potential sites before highway construction could begin. (Connecticut Joint Standing Committee Hearings [on] Roads, Bridges and Rivers part 2, 1955 Session, pp.545-547). But it was not until 1965 that the next statewide flight occurred.
Beginning in 1965, the Department of Transportation or the Department of Environmental Protection has contracted for statewide aerial surveys at approximately five-year intervals.
In 1969, when requesting funding for an aerial survey, Commissioner Joseph Gill of the Department of Agriculture and Natural Resources spoke about the many uses of aerial photographs to state agencies and municipalities. “[W]e have written to every town clerk, planning board in the state municipal governments, and have met with the various state agencies concerned with detailed mapping – such as the Highway Department and the State Planning Council and the State Development Commission and this is an effort on the part of all of these groups to obtain a standard aerial photo which will save, we hope, the towns in having to fly their own towns for assessment purposes…” (Connecticut Joint Standing Committee Hearings [on] Appropriations, 1969, part 1, pp.339-340)
The contract specifications for the 1990 Statewide Airphoto Flight say that the photographs are used extensively by the departments of Environmental Protection, Transportation, Public Works and numerous other state agencies. “In addition it is used by local municipalities for tax mapping and for land planning. Photos are also used by numerous private organizations and by individuals for providing information about land use and ground conditions.”
The State Library has the prints for 1965, 1970, 1975, 1980, 1985-1986, 1990 and 1995. Find out how to view the prints at the Research Guide to Aerial Photographs at the Connecticut State Library.
OTHER RESOURCES
Conclusion
There are also regulations relating to flying altitudes and speeds, especially in residential or developed areas. For this reason, you may not be able to use a piloted aircraft to capture your photographs. For projects such as real estate developments where photographs are required at an altitude of less than 500 meters, radio-controlled helicopters have provided a solution. Able to fly at relatively slow speeds compared to larger piloted aircraft and at much lower altitudes, radio-controlled aircraft can capture excellent aerial photographs for a real estate development project.
The type of aircraft used in aerial photography will depend largely on the subject matter and type of project. Shooting advertisements generally requires a great deal of mobility so a helicopter is usually the aircraft of choice. This is because a helicopter is able to hover in one position, fly straight up to gain greater perspective, turn at relatively sharp angles and even go backwards. For a more industrial application, such as geological aerial mapping, the area to be surveyed is usually quite large. It is also frequently uninhabited so limitations on flying speed and altitude are less of a concern. In this instance, the aircraft of choice will probably be a fixed wing airplane. It is usually fitted with a semi-automatic camera that is located under the belly of the aircraft.
Reference
-http://en.wikipedia.org
-Aerial photography and image interpretation
-Secrets of Successful Aerial Photography
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