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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 ...
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 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]
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 ...
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. [33] In the two years from June 2009 to May 2011, the USGS produced nearly 40,000 maps, more than 80 maps per work day. [33]
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.
Topographic maps are also commonly called contour maps or topo maps. In the United States, where the primary national series is organized by a strict 7.5-minute grid, they are often called or quads or quadrangles. Topographic maps conventionally show topography, or land contours, by means of contour lines.
Map produced with DLG data. DLGs are normally derived from USGS maps or USGS map-related sources. DLGs are distributed at three different scales: large-scale, which normally correspond to the USGS 7.5- by 7.5-minute, 1:24,000 and 1:25,000-scale topographic quadrangle map series, 1:63,360-scale for Alaska and 1:30,000-scale for Puerto Rico; intermediate scale, which are derived from the USGS 30 ...