Whats a DRG?
A DRG file is a scanned digital version of a USGS topographic map. It is actually a TIFF image file that can be opened in any digital imaging or photo viewing software that can open TIFF files (.tif, .tiff) to view the map just as you would a real-world paper version of the topographic map. Some additional information tags have been included in the TIFF file when the USGS created it to help mapping programs figure out what the actual location represented by that file is. These additional tags, combined with the digital scanned map, are often referred to as a GeoTIFF file.
