A digital raster graphic (DRG) is a digital image resulting from scanning a paper

USGS The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, a ...

topographic map In modern mapping, a topographic map or topographic sheet is a type of map characterized by large- scale detail and quantitative representation of relief features, usually using contour lines (connecting points of equal elevation), but historic ...

for use on a computer. DRGs created by USGS are typically scanned at 250

dpi A Daytona Prototype International (DPi) was a type of sports prototype racing car developed specifically for the International Motor Sports Association's WeatherTech SportsCar Championship, as their top class of car, acting as a direct replaceme ...

and saved as a

TIFF Tag Image File Format, abbreviated TIFF or TIF, is an image file format for storing raster graphics images, popular among graphic artists, the publishing industry, and photographers. TIFF is widely supported by scanning, faxing, word process ...

. The

raster Raster may refer to: * Raster graphics, graphical techniques using arrays of pixel values * Raster graphics editor, a computer program * Raster scan, the pattern of image readout, transmission, storage, and reconstruction in television and compu ...

image usually includes the original border information, referred to as the "map collar". The map file is UTM

projected Projected is an American rock supergroup consisting of Sevendust members John Connolly and Vinnie Hornsby, Alter Bridge and Creed drummer Scott Phillips, and former Submersed and current Tremonti guitarist Eric Friedman. The band released t ...

and

georeference Georeferencing means that the internal coordinate system of a map or aerial photo image can be related to a geographic coordinate system. The relevant coordinate transforms are typically stored within the image file ( GeoPDF and GeoTIFF are exam ...

d to the surface of the earth. DRG's are regularly used in

GIS A geographic information system (GIS) is a type of database containing Geographic data and information, geographic data (that is, descriptions of phenomena for which location is relevant), combined with Geographic information system software, sof ...

applications. DRGs were first produced in 1995.

External links

Libre Map Project The Libre Map Project is an online collection of all digital USGS 1:24K scale topographic maps (as well as various other GIS data) covering the United States, available as a free download. The Libre Map Project was started by Jared Benedict and aro ...

*
All 50 States USGS Topographic Maps on the Internet Archive
*
USGS Topographic Maps of ALL 50 States
*

Sites *
Digital Raster Graphics
*
Earth Explorer (GeoTIFFs)
*
Map Locator (GeoPDFs)

*

Pennsylvania Spatial Data Access Pennsylvania Spatial Data Access (PASDA) is Pennsylvania's official public access Geospatial analysis, geospatial information clearinghouse. PASDA serves as Pennsylvania's node on the National Spatial Data Infrastructure (NSDI). PASDA is a cooperati ...

sites *
Digital Raster Graphics for PA (free)
*
Digital raster graphics without collar info for PA (free)
* tp://www.pasda.psu.edu/pub/pasda/other_states/wv/drg24k FTP site, DRGs for West Virginia (free)* tp://www.pasda.psu.edu/pub/pasda/other_states/ny/drg24k FTP site, DRGs for New York (free)* tp://www.pasda.psu.edu/pub/pasda/other_states/va/drg24k FTP site, DRGs for Virginia (free)* tp://www.pasda.psu.edu/pub/pasda/other_states/md/drg24k FTP site, DRGs for Maryland (free)* tp://www.pasda.psu.edu/pub/pasda/other_states/dc/drg24k FTP site, DRGs for Washington DC (free)* tp://www.pasda.psu.edu/pub/pasda/other_states/de/drg24k FTP site, DRGs for Delaware (free)* tp://www.pasda.psu.edu/pub/pasda/other_states/nc/drg24k FTP site, DRGs for North Carolina (free)* Texas Natural Resources Information System *
DRGs without collars organized by county
Cartography GIS file formats United States Geological Survey {{Cartography-stub

See also

External links