The USGS released the Digital Map last week, so I tried out one of the sample digital topo maps overlying orthophotos, for the Tucson area.
The "Digital Map - Beta" is the first step toward a new generation of digital topographic maps delivered by the U.S. Geological Survey. These maps are built from The National Map data, which are integrated from local, State, Federal, and other sources. The initial version of the "Digital Map – Beta" includes orthoimagery plus roads and geographic names in the traditional 7.5 minute quadrangle format. "Digital Maps - Beta" are available free on the Web in the GeoPDF format. File size is about 15 to 20 Megabytes.
Tools are available free for download. Users can turn data layers on and off, zoom in and out, and print the maps. As the "Digital Map - Beta" evolves, the USGS will add historical versions of the topographic maps and will incorporate other data layers including hydrography and contours. Use of the term "Beta" signifies that these maps are initial versions that do not yet contain the full content of the traditional USGS topographic quadrangle maps.
The map/photo at right offers detail from the Cat Mountain, Arizona, Digital Map incorporating:
- National Agriculture Imagery Program (NAIP) orthoimagery (June 2007)
- Roads from the National Transportation Dataset (2008)
- Names from the Geographic Names Information System (2008)