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The Libre Map Project was started by Jared Benedict and around 100 additional individuals contributing money to purchase (or "liberate") a full set of 1:24K scale USGS topographic maps in Digital raster graphic form. [1] The map files were then hosted by archive.org to ensure the map data will continue to be freely available to everyone ...
A "quadrangle" is a topographic map produced by the United States Geological Survey (USGS) covering the United States. The maps are usually named after local physiographic features. The shorthand "quad" is also used, especially with the name of the map; for example, "the Ranger Creek, Texas quad". A quadrangle is defined by north and south ...
In 2008 the USGS abandoned traditional methods of surveying, revising, and updating topographic maps based on aerial photography and field checks. [34] Today's U.S. Topo quadrangle (1:24,000) maps are mass-produced, using automated and semiautomated processes, with cartographic content supplied from the National GIS Database. [34]
During the registration process, prospective volunteers submitted a list of the 7.5 minute quadrangle maps on which they wished to work. Once accepted into the project, volunteers received their assignment and 1:24,000 scale topographic map of their quad. While there was no deadline for completing maps, the project's administrators preferred ...
Figure 1. This BLM map depicts the principal meridians and baselines used for surveying states (colored) in the PLSS. The following are the principal and guide meridians and base lines of the United States, with the year established and a brief summary of what areas' land surveys are based on each.
A digital orthophoto quadrangle [1] (DOQ) is aerial photography or satellite imagery that has been corrected so that its pixels are aligned with longitude and latitude lines, and have a narrowly defined region of coverage. This is a widely used format introduced by United States Geological Survey (USGS). [1]
The United States Geological Survey Library (USGS Library) is a program within the United States Geological Survey (USGS), a scientific bureau within the Department of Interior of the United States government. The USGS operates as a fact-finding research organization with limited regulatory responsibility.
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