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A 'digital raster graphic (DRG)' is a digital image resulting from scanning a paper USGS topographic map for use on a computer. DRGs created by USGS are typically scanned at 250 dpi 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 and georeferenced to the surface of the earth. DRG's are regularly used in GIS applications.

Contents

External links

External links

★ Libre Map Project

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★ All 50 States USGS Topographic Maps on the Internet Archive

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★ USGS Topographic Maps of ALL 50 States

★ USGS Sites

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★ Digital Raster Graphics

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★ DRGs for the San Francisco Bay Area (free)

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★ DRGs for Alaska (free)

★ DRG Index for the United States For Google Earth

★ Kentucky Raster Graphics Image Download Center

★ Montana State Library Digital Raster Graphics download page

★ Pennsylvania Spatial Data Access sites

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★ Digital Raster Graphics for PA (free)

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★ Digital raster graphics without collar info for PA (free)

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★ [ftp://www.pasda.psu.edu/pub/pasda/other_states/wv/drg24k FTP site, DRGs for West Virginia (free)]

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★ [ftp://www.pasda.psu.edu/pub/pasda/other_states/ny/drg24k FTP site, DRGs for New York (free)]

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★ [ftp://www.pasda.psu.edu/pub/pasda/other_states/va/drg24k FTP site, DRGs for Virginia (free)]

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★ [ftp://www.pasda.psu.edu/pub/pasda/other_states/md/drg24k FTP site, DRGs for Maryland (free)]

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★ [ftp://www.pasda.psu.edu/pub/pasda/other_states/dc/drg24k FTP site, DRGs for Washington DC (free)]

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★ [ftp://www.pasda.psu.edu/pub/pasda/other_states/de/drg24k FTP site, DRGs for Delaware (free)]

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★ [ftp://www.pasda.psu.edu/pub/pasda/other_states/nc/drg24k FTP site, DRGs for North Carolina (free)]

★ Texas Natural Resource Information System

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★ DRGs without collars organized by county