Question: Which of the following is NOT descriptive of a DRG? Need Assignment Help? a) In GIS "lingo", a "DRG" refers specifically to a digitally scanned, topographic map. b) Topographic maps are used to show changes in elevation along with other physical and cultural features. c) The USGS is the coordinating agency that produces topographic maps and DRG products. d) DRG's are produced using the vector data structure, meaning they are made of individual points, lines and polygons, defining areas of vegetation, urbanization, roads and other cultural resources.