DRG Map

https://www.e-education.psu.edu/natureofgeoinfo/c6_p6.html

Above shown is an  example of a DRG map, which is short for a Digital Raster Graphic map, this map type is  result of the scan of a paper USGS topographic map.  These map types are created by USGS, and are regularly used for GIS applications.  DRG's are scanned from 250 pixels per inch per resolution, for example at 1:24,000 1 inch represents 2,000 feet on the ground and each DRG pixel corresponds to an area of about 8 feet.  The map above shows an area of Buskill, Pennsylvania
 mainly with the intention to depict the area of Depue Island and its surroundings.