This is a digital raster graphic (DRG) representation of Illinois taken from: http://www.isgs.uiuc.edu/nsdihome/browse/igq/product_001/sampleimages/drg_detail.jpgDRG is a scanned image of US Geological Survey topographic map. Geo-referencing information is added to these maps to associate them with their true position on the ground.
No comments:
Post a Comment