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, ...

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 histori ...

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. The raster 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 the ...

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 example ...

d to the surface of the earth. DRG's are regularly used in GIS applications. DRGs were first produced in 1995.

External links

* Libre Map Project *
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 information clearinghouse. PASDA serves as Pennsylvania's node on the National Spatial Data Infrastructure (NSDI). PASDA is a cooperative effort of the Pen ...

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