#GROUND CONTROL POINTS ARCHIVE#

#GROUND CONTROL POINTS ARCHIVE#

The NGS's Imagery Ground Control Point Archive is currently accessible in Goggle Earth's KMZ format. 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 may be used to verify the accuracy of existing georeferenced imagery (including orthomosaics), supplement other photogrammetric control, or when planning an image acquisition. The well-defined points are surveyed in most cases to an accuracy of 3 decimeters horizontally and 5 decimeters vertically unless otherwise reported. Imagery ground control points are tied to the NSRS using standard field surveying methods.

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.

These ground control points were used to georeference the aerial imagery to the National Spatial Reference System. 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. NGS also maps the coastal regions of the United States and provides data for navigational charts. 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. 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.

Ground control points