DRG

DRG maps or digitally rastered graphic maps you a combination of topographic maps and reproduces them in a digital form. The digital form is produced by using a resolution of 500 green, blue, and red dots per square inch. These maps are useful in the collection of digital data. I selected the map below because it was the most vivid in detail giving the best example of the capabilities of DRG maps.




http://egsc.usgs.gov/isb/pubs/factsheets/fs08801.graphics/drg.jpg