USGS Topographic Maps
The Indiana Spatial Data Portal (ISDP) archive provides the USGS digital topographic maps in two different products: the digital raster graphic (DRG) legacy product and the new US Topo product. The legacy DRG's are available in TIFF format (with or without the map border) and GeoPDF® format. The ISDP archive includes the DRG 7.5-minute (1:24,000), 30 x 60-minute (1:100,000), and the 1 x 2 degree (1:250,000) series maps.
The ISDP now offers all of Indiana's US Topo maps. The US Topo maps are constructed in GeoPDF® format from key layers of geographic data – orthoimagery, roads, geographic names, contours and hydrographic features - found in The National Map, which is a nationwide collection of integrated data from local, State, Federal, and other sources.
The Digital Raster Graphic (DRG) is a scanned, digital image of a US Geological Survey (USGS) standard series topographic map. The original DRG images included the full map extent and surrounding map border information. To produce the DRGe product, the USGS removed map borders and appended portions of surrounding map images to create rectangular images which are suitable for seamless tiling in a geographic information system.
Spatial Reference System: Users can select from Latitude/Longitude, Universal Transverse Mercator, and Military Grid Reverence System
File Format: GeoPDF®
Direct "mash-up" capabilities with Google Maps®
Spatial Reference System: UTM, Zone 16 North; both NAD27 and NAD83 worldfiles are included with archives
File Format: GeoTiff (5-10 MB/File) - with and without border; GeoPDF®
Scale: 1:24,000, 1:100,000 and 1:250,000
Resolution: scanned at 250 dots per inch