What is NAPP/NHAP photography?
The National High Altitude Photography (NHAP) program was initiated in 1980 and coordinated by the U.S. Geological Survey to acquire aerial photography of the 48 conterminous United States every 5 years. This interagency program was designed to eliminate duplicate efforts in various Government programs and to maximize the use of Government funds to build a uniform archive for multiple purposes. In 1987, the program name was changed to the National Aerial Photography Program (NAPP) in recognition of modifications in the user requirements and flight specifications.
The NAPP photography are acquired at 20,000 feet above mean terrain with a 6 inch focal length lens. The flight lines are quarter quad-centered on the 1:24,000-scale USGS maps. NAPP photographs have an approximate scale of 1:40,000, and are acquired on Black-and-White (B/W) or Color-Infrared (CIR) film, depending on state or federal requirements.
The NHAP photography were acquired at 40,000 feet above mean terrain and flight lines were centered on the 1:24,000-scale USGS map series. Two different camera systems were used; a 6 inch focal length lens was used to acquire B/W film at an approximate scale of 1:80,000 and an 8.25 inch lens was used to acquire CIR film at an approximate scale of 1:58,000.