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| Earth Resources Observation and Science (EROS) |
National Aerial Photography Program (NAPP)
The National Aerial Photography Program (NAPP), is an interagency Federal effort coordinated by the USGS, which uses NAPP products to revise maps. Other agencies have varied uses for these photographs, which, are taken on a 5- to 7-year cycle and produced to rigorous specifications. The NAPP program encompasses the entire lower 48 states and Hawaii. The photos are acquired from airplanes flying at an altitude of 20,000 feet using a 6 inch focal length camera resulting in a scale of 1:40,000. Each 9-by 9-inch photo (without enlargement) covers an area of slightly more than 5 miles on a side. The NAPP program began in 1987 and replaced the National High Altitude Photography (NHAP) program which was initiated in 1980. Flightlines for the NAPP program are flown in a north-to-south direction through the east and west halves of 7.5-minute quadrangles. The original purpose of the NAPP program was to provide the U.S. Geological Survey with accurate and cloud-free photographs which would assist them in the creation and revision of USA topographic maps. NAPP photographs are obtained on 9-inch film from an altitude of 20,000 feet above mean terrain elevation, and are centered on quarters of 7.5-minute quadrangles. Strict specifications regarding sun angle, cloud cover, minimal haze, stereoscopic coverage, and image inspection were followed. All NAPP photography is cloud-free.
While it was the intent of both the NHAP and NAPP programs to acquire complete coverage of the conterminous United States every five years, that has varied somewhat due to budgetary constraints. These programs provide nearly complete coverage of the entire United States on a fairly regular basis. The current cycle of NAPP coverage spans 1997 - 2003.
Flight season, film type, and coverage requirements are negotiated each year based upon available funds from the contributing federal and state agencies and the operational requirements of those agencies. (A list of contributing federal agencies is included in the Appendix.)
 NAPP Seven Year Acquisition Plan 1997 - 2003 (70 kb) |
 NAPP Second Cycle 1992 - 1996 (28 kb) |
 NAPP First Cycle 1987 - 1991(28.3 kb) |
The NAPP/NHAP archive contains over 10,000 rolls of cartographic quality aerial photography acquired since 1980. On the average, 700 new rolls are acquired each year based upon a pre-determined flight schedule and season. Strict specifications regarding sun angle, cloud cover, minimal haze, stereoscopic coverage, and image inspection are followed. All photographs are cloud free, and only contract-acceptable photographs are indexed to the map line plots. The photographic frames are maintained as original and working master archives by two support facilities, the USGS EROS Data Center and the U.S. Department of Agriculture's Aerial Photographic Field Office (APFO).
All photographs are manually assessed to ensure that they meet the photographic, cartographic, coverage accuracy, and quality standards of each contract. Commercial flight contractors must meet a stringent list of acceptance criteria and provide proof of camera certification in order to fulfill contract requirements.
NAPP photography has a resolution of one meter.
The NAPP photography are indexed using map line plots available on microfiche and supported by a data base that is maintained by the managing centers. User inquiries are answered through the use of these map plots. NAPP photography are indexed on 1:100,000-scale USGS maps.
All NAPP photography can be searched and ordered through Photofinder (a "quick and easy" search and order tool devoted soley to NAPP photography) at: http://edc.usgs.gov/photofinder, EarthExplorer at: http://earthexplorer.usgs.gov/, or GloVis (a browse-based search engine)
Information about NAPP products and services can be found at: http://edc.usgs.gov/products/aerial/napp.html
The NHAP/NAPP archive is an invaluable source of high quality, cloud free, quad-based photography for the conterminous U.S. The photography can be integrated into Geographic Information Systems (GIS) as base images :1 through high resolution scanners or they can be used to manually interpret land use, land cover, and feature changes when compared to other photography or satellite imagery acquired from earlier or later time periods.
The following Federal agencies have contributed funds to NAPP:
U.S. Department of Agriculture (USDA)
U.S. Department of Interior (DOI)
Tennessee Valley Authority (TVA)
The black-and-white film emulsion shall be sensitive to red, green, and blue wave lengths (electromagnetic spectrum), and shall have an extended red sensitivity to approximately 720 to 750 nanometers. The film shall be exposed and processed to obtain a minimum density (D-min) of not less than 0.30 density units above base plus fog and a maximum (D-max) not in excess of 1.50 units above base plus fog. The aim point for density range is 1.0 density units for the average frame.
All color-infrared film shall be exposed and processed to the manufacturer's specifications. The CIR emulsion shall be sensitive to the visible and near infrared spectrum from 400 to 900 nanometers (electromagnetic spectrum).
Flight specifications for the NAPP program require that all photographs meet certain standards regardless of the geographic area involved. The sun angle is thirty percent or higher to reduce potential shadow effects on the ground. Cloud cover must be absent, and atmospheric haze must be minimal. Even seasonal factors such as the presence of snow on the ground, flooding, or the amount of foliage are considered prior to accepting the photography. The center point of each photograph must also fall within a 1,000 foot radius of a pre-determined position within the north-south flight lines. Camera tilt shall not exceed four degrees, nor average more than two degrees, in any ten mile section of a flight, nor average more than one degree for the entire flight contract.
Quarter Quad-Centered
The NAPP photographs are acquired over pre-determined exposure points within a 7.5 minute quadrangle map. The principal points of exposure divide the quad into quarter sections. Each section involves a 3.75 minute sub-quadrangle. The NAPP flight lines run north-south down the middle of these quarter-quads.
|------ * ------|------ * ------|
| . | . | \
| . | . | \
. | * | * | \
/|\ | . | . | \
| | . | . | \
N |------ * ------------- * ------| \ 7.5 minute
| . | . | / Quadrangle
| . | . | /
| * | * | / * = pre-determined
| . | . | / exposures
| . | . | /
|------ * ------|------ * ------| / . = flight line
trace
The NAPP photographs are indexed by using 1:100,000 USGS series maps. The center points, roll, and frame number of all accepted photographs are plotted on the maps. The maps are further annotated with project names, roll numbers and roll acquisition dates in the map margin. The resulting map line plot is then microfilmed and sleeved into microfiche jackets. The microfiche are duplicated and sent out to distribution sites and information offices as subscription catalogs. The microfiched map line plots are also sent out to answer coverage inquiries or paper blow-back copies are made upon request.
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