Enables locating and ordering aerial photography produced under the National Aerial Photography Program (NAPP)from the EROS data center with links to product description, prices, search & order, custom enlargements and certification.
Links to standards prepared under the National Mapping Program to produce and maintain top quality mapping and geospatial data products. Documents may be viewed and downloaded in PDF and HTML formats with links to related information.
USGS Archive for preservation and access for satellite remote sensing data and imagery (Landsat and AVHRR). Links to locating and ordering imagery, international collaborators, advisory committee, and Earthshots (satellite photos.).
Explains how the NHD specifies point locations within streams by using a code to indicate the reach (including the hydrologic unit) and a measure, which indicates how far the point is from the downstream end of the reach.