1:250k Digital Raster Graphic - Collars Removed

A digital raster graphic (DRG) is a scanned image of an 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.<br/><br/>DRG's are created by scanning published paper maps on high-resolution scanners. The raster image is georeferenced and fit to the UTM projection. Colors are standardized to remove scanner limitations and artifacts. The average data set size is about 6 megabytes in Tagged Image File Format (TIFF) with PackBits compression. DRG's can be easily combined with other digital cartographic products such as digital elevation models (DEM) and digital orthophoto quadrangles (DOQ).<br/><br/>DRG's are stored as rectified TIFF files in geoTIFF format. GeoTIFF is a relatively new TIFF image storage format that incorporates georeferencing information in the header. This allows software, such as ArcView, ARC/INFO, or EPPL7 to reference the image without an additional header or world file.<br/><br/>Within the Minnesota Department of Natural Resources Core GIS data set the DRG's have been processed to be in compliance with departmental data standards (UTM Extended Zone 15, NAD83 datum) and the map collar information has been removed to facilitate the display of the DRG's in a seamless fashion.<br/><br/>These DRG's were clipped and transformed to UTM Zone 15 using EPPL7 Raster GIS.

Additional Info

Field Value
Last Updated November 19, 2015, 11:02
Created November 18, 2015, 11:02
dsAccessConst None
dsCurrentRef The scanned USGS Topographic map
dsMetadataUrl ftp://ftp.gisdata.mn.gov/pub/gdrs/data/pub/us_mn_state_dnr/base_usgs_scanned_topo_250k_drg/metadata/metadata.html
dsModifiedDate 2015-11-18 16:18:58
dsOriginator U.S. Geological Survey and Minnesota DNR
dsPeriodOfContent 1/1/1998
dsPurpose The DRG is used for validating digital line graphs (DLGs) and for DLG data collection and revision. The DRG can help assess the completeness of digital data from other mapping agencies. It can also be used to produce hybrid products. These include combined DRGs and DOQs for revising and collecting digital data, DRGs and DEMs for creating shaded-relief DRGs, and combinations of DRG, DOQ, and DLG data. Although a standard DRG is an effective mapping tool, its full potential for digital production is realized in combination with other digital data. Clipping the collar information allows seamless viewing of adjacent DRGs. Standardizing the UTM zone and the datum matches the data with many other statewide datasets available in Minnesota.

Dataset extent