DRG

DRG- Digital Raster Graph. Created through a Geographic Information System (GIS), this is a scanned image of a US Geological Survey (USGS) standard series topographical map, including all map collar (original map border) information. These are georeferenced to the surface of the earth, the Universal Transverse Mercator projection, and the State Plane Coordinate System. Information is scanned at a minimum resolution of 250 dots per inch. Cartographic data is recorded, stored, and processed in a cell or pixel (raster format). Each map covers a quadrangle (quad), four-sided area of 7.5 minutes of latitude and 7.5 minutes of longitude. Quads can be combined to form larger maps. This is a DRG of Emerald Bay in Lake Tahoe, communicating topography, location, and physical features of the area (http://tahoe.usgs.gov/GIS.html).