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The National High-Altitude Photography Program
By Charles W. Beetschen
High-altitude photography—aerial photography taken from aircraft operating at altitudes of 40,000 feet and above— has been recognized for many years as one of the most versatile, accurate, and economical remote sensing techniques used to evaluate, map, and monitor the Nation's resources and environment. Federal and State agencies and private users make extensive applications of highaltitude photography in mapping and charting and in studies of topography, geology, hydrology, land use and land cover, soils, wetlands, and other resources. In sitespecific studies, high-altitude photography provides information to estimate timber volumes, to detect crop diseases and forestry infestations, to take wildlife censuses, to estimate traffic flows, to plan highway and pipeline routes, to aid in archeological investigations, and for many other applications concerned with the inventory, management, and development of natural and manmade features. Highaltitude photography taken at frequent intervals over the same area provides information necessary for change detection, such as observation of shoreline changes in the coastal zone, changes in land use and land cover, or alterations in the landscape caused by floods, storms, and other natural disasters. When used with other forms of remote sensing in a systems approach to data acquisition and analysis, high-altitude photography aids in providing spatial data important to thematic mapping and land use planning and management (fig. 1).
In recognition of the multiple uses of high-altitude photography now and in the foreseeable future and the need to acquire photography in the most efficient manner. Federal agency users agreed in 1978 to consolidate their requirements and to pool their resources in a coordinated costsaving effort to systematically photograph the approximately 3 million square miles of the conterminous United States (48 States). The agreement provided for the establishment in 1980 of a National HighAltitude Photography Program designed to develop a national high-altitude photographic data base composed of black-andwhite and color-infrared photography. The
U.S. Geological Survey, the principal coordinating agency, shares the responsibilities for program planning and for funding the acquisition of photography with 12 other Federal agencies participating in the program. When the remaining photographs for the national high-altitude photography data base are acquired in 1986, the Nation will have for the first time complete photographic coverage at uniform scale of the conterminous United States.
High-altitude photography became a reality in the 1950's and 1960's as a result of improvements in aircraft and photographic technology during World War II and the immediate postwar period. These innovations included the introduction of new propulsion systems, pressurization, and other design changes to aircraft to permit high-altitude operations; modifications to photographic systems including the use of color and color-infrared films providing a high degree of spatial resolution and spectral discrimination; significant new photogrammetric equipment and procedures that could prepare a standard mapping product to prescribed national standards of accuracy and content; and many other improvements. During this period, high-altitude photography depended on the use of military aircraft converted for civilian applications. The high cost of flight operations for these aircraft counterbalanced the savings in production costs normally realized from application of photography taken at higher altitudes. Federal agencies deferred major acquisitions of high-altitude photography until a more cost-effective photographic system was developed.
In the late 1960's, the introduction of a small business jet capable of operating at high altitudes provided commercial aerial survey firms an aircraft that required modest capital outlay and made the acquisition of high-altitude photography economically feasible for Federal agencies. Interest in high-altitude photography intensified, and competition began for the services of the few aircraft available. However, individual agencies planned for the acquisition of high-altitude photography with only minimal coordination of requirements. The result was duplication of photography in
some areas of the country, a lack of photography in others, and a slowdown in programs relying on high-altitude photography for data acquisition and analysis. A large amount of high-altitude photography was acquired, but with little semblence of national coverage; also lacking was a central source where all users could obtain information about the availabilty of existing photographic coverage.
The Geological Survey, exercising responsibilities for coordination of aerial photography assigned under Office of Management and Budget Circular A-16, began preliminary studies in 1970 to identify the needs of the Federal agencies for high-altitude photography with the objective of developing a program to achieve national coverage.
In 1 972, the Federal Mapping Task Force on Mapping, Charting, Geodesy and Surveying was established by the Office of Management and Budget to conduct a broad study on how best to use Federal resources to meet overall cartographic requirements. The 1973 report of the task force recommended a centrally coordinated effort to assemble, review, and validate the aerial photographic needs of all civilian agencies and indicated the need for a central source to provide information to all users about existing aerial photography.
During the next several years, the Geological Survey continued studies to determine Federal agency requirements for highaltitude photography. A separate survey was conducted by the U.S. Department of Agriculture to identify agency data needs to support departmental programs. This survey indicated that high-altitude colorinfrared photography would support a majority of the data needs that could be satisfied by photographic film sensors. The information from the Department of Agriculture, combined with similar results from the Geological Survey, provided sufficient justification for a single draft proposal for a National High-Altitude Photography Program which could be submitted to other interested Federal agencies for review.
In August 1978, the Geological Survey invited representatives of 24 Federal agencies to meet and discuss the draft proposal, to identify the products, and to consider funding procedures. The agency
representatives fully supported the need for a national program which would lead to the formation of a high-altitude photography data base for the conterminous
United States, eliminate duplication by consolidating the needs of many Federal and State agencies, result in substantial savings in the cost of acquiring highaltitude photography, and make highaltitude photography readily available to all users, both public and private.
An interagency steering committee was organized to consider the findings of the August 1 978 meeting and to complete a program proposal. Discussions were held with potential commercial aerial survey firms on the technical requirements of the program and with Federal agencies to identify priority areas and funding for the firstyear flight operations and to discuss the processing of film and distribution of products. The plan for a National High-Altitude Photography Program was approved by the Federal agencies in 1979, and contracts were awarded to commercial aerial survey firms to permit the start of photographic operations in fiscal year 1980.
Program Description and Products
The jet aircraft employed in the National High-Altitude Photography Program by the commercial contractors are equipped with 9- by 9-inch format precision aerial mapping cameras. These cameras take vertical aerial photographs that are compatible with precision stereoscopic mapping equipment. One camera has a 6-inch (1 53millimeter) focal length lens, uses Kodak 2405 panchromatic black-and-white film, and produces a photograph at a scale of 1:80,000 (1 inch equals about 1.25 miles). The other camera has an 8 V* -inch (210-millimeter) focal length lens, uses Kodak 2443 color-infrared film, and produces a photograph at a scale of 1:58,000 (1 inch equals about 0.9 mile). Each black-and-white photograph covers an area of about 1 30 square miles; each color-infrared photograph covers an area of about 68 square miles. The theoretical ground resolution of both black-and-white and color-infrared photographs is approximately 6V2 feet (2 meters).
The aircraft fly in a north-south direction over predetermined flight lines along the centers of Geological Survey 7.5-minute
quadrangles at an altitude of 40,000 feet above mean terrain. Film is exposed over ground stations established in advance of the flight missions and patterned to produce overlapping photographs required for stereoscopic coverage (fig. 2). There are an average of three black-and-white exposures and four color-infrared exposures for each 7.5-minute quadrangle. Approximately 120,000 black-and-white photographs and 175,000 color-infrared photographs are required for complete coverage of the conterminous United States.
Photographic operations must consider the flying season and other environmental factors. The flying season selected for the initial coverage of the 48 States is the leaf-off season. This time of the year is of primary concern in the deciduous forest areas generally located east of 96° west longitude. Useful photography can be taken only when the Sun angle is greater than 30° and when cloud cover, snow, smoke, and haze are absent. Photographs
cannot contain hot spots (reflections) or excessive shadowing. These requirements limit the flying season to specific time periods for all areas of the conterminous United States so that no single area can be flown throughout the year. Generally, flights are limited to spring in the deciduous forest areas. Photographic operations in all areas are subject to seasonal changes and local variations in terrain.
The primary products of the National High-Altitude Photography Program are 9- by 9-inch black-and-white and colorinfrared photographs in film or paper-print format. Film positives and paper prints are available for black-and-white and colorinfrared in the 9- by 9-inch size; however, a film negative is available as a standard product for only the black-and-white photography. Photography from the National High-Altitude Photography Program is not for the exclusive use of the Federal agencies but is available to everyone.
The Geological Survey's National Cartographic Information Center serves as the central source for information about the National High-Altitude Photography Program and the approximately 13 million frames of aerial photography acquired by other programs. Photography from the National High-Altitude Photography Program can also be obtained directly from the primary processing and distribution centers of the Earth Resources Observation Systems Data Center in Sioux Falls, South Dakota, or the Agricultural Stabilization and Conservation Service in Salt Lake City, Utah.
Current Program Organization and Status
The National High-Altitude Photography Program Steering Committee established in 1978 continues as the principal organizing and coordinating body for the program. The committee considers short- and long
range program objectives and new requirements for high-altitude photography. The committee is chaired by the Geological Survey, with member representatives from the Soil Conservation Service and the Agricultural Stabilization and Conservation Service, Department of Agriculture; the Bureau of Land Management, Department of the Interior; the U.S. Army Corps of Engineers, Department of Defense; and the Tennessee Valley Authority. Representatives from the Office of Surface Mining, Department of the Interior, and the Defense Mapping Agency, Department of Defense, serve as ad-hoc members in an advisory capacity.
Each year, the committee hosts a conference where representatives from the Federal agencies participating in the program review status and progress, identify priority areas for photographic missions during the succeeding year, and indicate the level of funding support available for that year. A plan for photography is prepared which balances the requests for
photographic coverage with the amount of funding available from each agency.
Since the beginning of the program in fiscal year 1980, a total of 2.85 million square miles, or 93 percent of the area of the conterminous United States, has been contracted. About 52 percent of the contracted photography has been completed and is available to users (fig. 3). The final 7 percent of the area will be contracted in fiscal year 1985. All contracted photography is scheduled to be completed in fiscal year 1986.
Federal agencies that have provided financial support for the National HighAltitude Photography Program are Agricultural Stabilization and Conservation Service, Forest Service, Soil Conservation Service, and Statistical Reporting Service of the Department of Agriculture; U.S. Army Corps of Engineers and the Defense Mapping Agency of the Department of Defense; Bureau of Indian Affairs, Bureau of Land Management, Bureau of Mines, Geological
Survey, National Park Service, Office of Surface Mining, and Fish and Wildlife Service of the Department of the Interior; and the Tennessee Valley Authority.
Future of National High-Altitude
On completion of the initial photographic coverage of the conterminous United States, the National High-Altitude Photography Program will be directed toward a second photographic cycle based on the coordinated requirements of Federal and State agencies and other users. Under the aegis of the program's interagency steering committee, studies are in progress to review the need for extending photographic coverage to Alaska, Hawaii, and other areas; to examine the use of new cameras, films, and other modifications to current photographic systems; to investigate requirements for changes in the flying