Since the late 1930s, high-resolution, georeferenced aerial photography for defining the nation's 95,000-mile has been a responsibility of the , part of NOAA's National Ocean Service (NOS). Metric aerial photographs are the primary source material used for creating coastal survey maps and digital cartographic feature files. These data sets, in turn, provide data for producing NOAA .
Determining the accurate location of the shoreline is extremely important because it is used as a source to define the boundaries between private, state, and federal ownership and jurisdictions, including the territorial sea and the Exclusive Economic Zone. Tidal datum lines derived from the NOAA nautical chart are a source used to determine such marine and maritime limits. These photographs have many other uses as well, including coastal management, waterfront development, natural resource identification, water-depth measurements, topographic mapping, sea-bed characteristic mapping, and location of features or obstructions to ensure the safety of marine and air navigation.
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 NGS. 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.
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.
The public's primary access to NOS aerial photography is via NOS's Web site. On this Web site, coastal maps (nautical charts without navigation aids), shoreline surveys (for mapping the official U.S. shoreline), coastal aerial photography, environmental sensitivity index maps, geodetic control points, maritime boundaries, estuarine bathymetry, and water-level stations are available. The site includes over 14,000 aerial photographs taken since 1990.
The NOAA 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 , a nationwide effort to improve the use of geographic data within the United States.
A major project involving aerial photography and shoreline mapping is the . 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 (CSC) is significantly involved in this project.
Land cover represents another important data resource for those who manage coastal resources. Land-cover maps document how much of a region is covered by forests, wetlands, impervious surfaces, agriculture, and other land and water types. The maps are created using remotely sensed data, which include both satellite and airborne imagery. No other technology provides a better big-picture view of a region.
Most of the nation’s coast is included in the baseline dataset. By comparing maps from various years, users can see how the land surface changes over time. This information not only helps when gauging current conditions, but also plays an important role when crafting policies that direct future land-use decisions.
The, a special NGS project, analyzes shoreline changes by comparing recent high-resolution satellite imagery or high-altitude reconnaissance aerial photography with existing NOAA nautical charts. By digitally overlaying the satellite imagery with charts, changes in shoreline features (piers, bulkheads, shoreline configuration, jetties, groins, etc.) can be easily detected. Shoreline changes are used to aid updating nautical charts.
Revised July 12, 2012
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