USGS Digital Raster Graphics (DRG) - A digital raster graphic (DRG) is a scanned image of a U.S. Geological Survey (USGS) standard series topographic map, including all map collar information. The image inside the map neatline is georeferenced to the surface of the earth and fit to the Universal Transverse Mercator projection. The horizontal positional accuracy and datum of the DRG matches the accuracy and datum of the source map. The map is scanned at a minimum resolution of 250 dots per inch. How to Read the Universal Transverse Mercator (UTM) Grid DRGTools - a set of programs for manipulating USGS Digital Raster Graphics (DRG) Topographic Maps.These programs are free software; you can redistribute them and/or modify them under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. Documentation and Tools for Utilizing USGS Digital Raster Graphic Data - The DRG-Tools extension provides tools for edgematching (mosaicking) Digital Raster Graphic (DRG) scanned quad images created by the Teale Data Center (Teale), the Tennessee Valley Authority (TVA), and the United States Geological Survey (USGS). Other utilities are also provided, including options for isolating specific image features such as contours or hydrography. Reading UTM Coordinates From DRGs Map Accuracy Standards Finding Your Way with Map and Compass Documentation and Tools for Utilizing USGS Digital Raster Graphic Data     © Copyright 2007 - Samuel J. Wormley   by swormley1@gmail.com