NOS analyzes high-resolution satellite imagery and high-altitude aerial photography to evaluate coastline changes. Digitally overlaying the imagery (shown in green) with the charts developed earlier reveals changes in shoreline features.

Since the late 1930s, high-resolution, georeferenced aerial photography for defining the nation’s 95,000-mile shoreline has been a responsibility of the National Geodetic Survey, part of NOAA’s National Ocean Service (NOS). Precision aerial photography is the primary source material used for creating coastal survey maps and digital cartographic files. These data sets, in turn, provide data for producing NOAA nautical charts. Determining the accurate location of the shoreline is extremely important because it defines the boundaries between private, state, and federal ownership and jurisdictions, including the territorial sea and the Exclusive Economic Zone. These photographs have many other uses as well, including coastal management, waterfront development, natural resource identification, measuring water depths, topographic mapping, mapping seabed characteristics, and locating features or obstructions to ensure the safety of marine and air navigation.

Above: High-altitude aerial photography, Hudson River, NY. Below: Same area on a NOAA nautical chart. Comparing these sources, created at different times, provides information on the rate of change in the coastal zone, which aids in the design of coastal zone mapping projects. (Click image for larger view)

Products and Mission

The primary aerial photographic product is a 9x9-inch color photograph usually at scales from 1:10,000 to 1:50,000. More than 500,000 photo negatives, dating from 1945 to the present year, exist in NOS archives and are maintained by NOS’s National Geodetic Survey. Aerial photography surveys are conducted on varying time cycles, depending on the amount of change caused by human or natural forces. Other types of photographs include panchromatic, false-color infrared, and black-and-white infrared.

For most photographic missions, NOS deploys a fanjet aircraft equipped with dual-camera capability. This allows two types of photographs to be collected concurrently, if conditions allow. Photography is acquired when weather conditions, sun angle, and, when applicable, water levels are optimal to ensure that photographs will be suitable for a variety of purposes using standard photogrammetric techniques. NOS now manages the majority of its mapping projects through contracts with private mapping firms. These firms are responsible for every phase of project completion, from acquiring aerial photographs to generating digital cartographic feature files.

Web Access

The public’s primary access to NOS aerial photography is via NOS's Data Explorer Web site. On this Web site, coastal survey maps, coastal photography, historical maps and charts, environmental sensitivity index maps, geodetic control points, historical maps and charts, hydrographic survey outlines, nautical charts, and water level stations are available. The site includes approximately 41,000 aerial photographs taken since 1990.

The NOAA Coastal Shoreline Mapping Web site provides the ocean and coastal resource management community with data and information related to shoreline mapping. It contains links to digital data, references pertaining to the legal and technical aspects of the shoreline, and organizations that are working to support the collection of shoreline data for the coastal component of the National Spatial Data Infrastructure, a nationwide effort to improve the use of geographic data within the United States.

NOS scientists used LIDAR images to aid recovery efforts at the World Trade Center disaster site. The images allowed building and utility engineers to locate original foundation support structures, elevator shafts and basement storage areas, and pinpoint digging and recovery efforts.

Related Projects and Technologies

A major project involving aerial photography and shoreline mapping is the Topographic Change Mapping project. This project involves acquiring high-resolution topographic data through remote-sensing technologies for coastal resource managers. Topography is the general shape or form of land surface, including its relief and arrangement of features. NOAA Coastal Services Center (CSC) is significantly involved in this project.

Both NGS and CSC are using new remote-sensing technologies to map coastal topography and the shoreline in the United States. These include Light Detection and Ranging (LIDAR), Interferometric Synthetic Aperture Radar (IfSAR or InSAR), and Airborne Visible and Infrared Imaging System (AVIRIS).