Imagery Ground Control Point Archive
The National Oceanic and Atmospheric Administration's National Geodetic Survey (NGS) defines and manages the National Spatial Reference System (NSRS), a national coordinate network system, that provides the foundation for mapping and charting; transportation and communication; and a multitude of scientific and engineering applications. Committed to making transportation and navigation safer, NGS conducts aerial photogrammetric surveys near airports in the United States and its possessions to position obstructions and aids to air travel. NGS also maps the coastal regions of the United States and provides data for navigational charts.
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The NGS's Imagery Ground Control Point Archive generally comprises of ground control point coordinates, sketches, metadata, and ground view digital photographs of photo-identifiable points used in recent NGS aerial photogrammetric surveys. These ground control points were used to georeference the aerial imagery to the National Spatial Reference System. Imagery ground control points are well-defined points on the ground that are easily identifiable on the aerial imagery, well distributed throughout the project area, and have ground surveyed positions or coordinates (latitude, longitude, and height) on the Earth. Imagery ground control points are tied to the NSRS using standard field surveying methods. The well-defined points are surveyed in most cases to an accuracy of 3 decimeters horizontally and 5 decimeters vertically unless otherwise reported. |
The NGS's Imagery Ground Control Point Archive may be used to verify the accuracy of existing georeferenced imagery (including orthomosaics), supplement other photogrammetric control, or when planning an image acquisition. Using existing photogrammetric control may reduce cost by reducing the time spent or eliminating the need for sending out a field survey crew to collect new ground survey control points.
The NGS's Imagery Ground Control Point Archive is currently accessible in Goggle Earth's KMZ format. The KMZ file is organized by State and project identifier. For aeronautical surveys the project identifier is the Federal Aviation Administration's airport Location IDentifier (LID). For coastal mapping surveys the project identifier is an internal identifier. More information for this ground control point may include coordinates, metadata, sketches, and ground view digital photographs. An ASCII comma delimited format file (CSV) of the projects geodetic positions may be downloaded.
Click here to download the NGS Image Control Archive!
These data were generated for use by NGS during the course of its development of potential final products to fulfill its statutory mission. Although NGS is making these data available to others who may find the data of value, NGS does not warrant, endorse, or recommend the use of these data for any given purpose. The user assumes the entire risk related to the use of these data. NGS is providing these data "as is," and NGS disclaims any and all warranties, whether expressed or implied, including (without limitation) any implied warranties of merchantability or fitness for a particular purpose. In no event will NGS be liable to you or to any third party for any direct, indirect, incidental, consequential, special, or exemplary damages or lost profits resulting from any use or misuse of these data.
Inquiries, questions, comments, or recommendations concerning all NGS aeronautical products, including the Image Control Archive, should be directed to:
Aeronautical Data Coordinator:
uddf @ ngs.noaa.gov