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GeoPDF products are used to deliver maps and imagery from multiple US government agencies. Quadrangles of The National Map are available from the USGS store in as GeoPDF products and are free to download. The US Army Corps of Engineers distributes GeoPDF maps through the U.S. Army Corps of Engineers Topographic Engineering Center.
GeoTIFF is a public domain metadata standard which allows georeferencing information to be embedded within a TIFF file. The potential additional information includes map projection, coordinate systems, ellipsoids, datums, and everything else necessary to establish the exact spatial reference for the file. The GeoTIFF format is fully compliant ...
A small portion of a USGS DRG. A digital raster graphic (DRG) is a digital image resulting from scanning a paper USGS topographic map for use on a computer. DRGs created by USGS are typically scanned at 250 dpi and saved as a TIFF. The raster image usually includes the
[2] The National Map is part of the USGS National Geospatial Program. [3] The geographic information available includes orthoimagery (aerial photographs), elevation, geographic names, hydrography, boundaries, transportation, structures and land cover. The National Map is accessible via the Web, as products and services, and as downloadable data ...
The related OGR library (OGR Simple Features Library [2]), which is part of the GDAL source tree, provides a similar ability for simple features vector graphics data. GDAL was developed mainly by Frank Warmerdam until the release of version 1.3.2, when maintenance was officially transferred to the GDAL/OGR Project Management Committee under the ...
In 1995 the USGS was in need of a Windows viewer for their data products, so they developed the dlgv32 application for viewing their DLG (Digital Line Graph) vector data products. Between 1995 and 1998 the dlgv32 application was expanded to include support for viewing other USGS data products, including DRG (topographic maps) and DEM (digital ...
The USGS DEM format is a self-contained (single file) set of ASCII-encoded (text) 1024-byte (1024 ASCII chars) blocks that fall into three record categories called A, B, and C. There is no cross-platform ambiguity since line ending control codes are not used, and all data including numbers is represented in readable text form.
The site is an interactive map of the United States that allows users to search or move around the map to find the USGS collection of maps for a specific area. Users may then view the maps in great detail and download them if desired. [33]