Friday, December 04, 2009

Digital US Topo maps, available

“US Topo” is the next generation of topographic maps from the U.S. Geological Survey. Digital US Topo maps are designed to look, feel, and perform like the traditional paper topographic maps for which the USGS is so well known. However, in contrast to paper-based maps, US Topo maps provide technical advantages that support faster, wider public distribution and enable basic, on-screen geographic analysis for all users.

“The public’s high regard for USGS topographic maps stretches over a century,” said Secretary of the Interior Ken Salazar. “Because Survey maps consistently describe our nation’s entire landscape, they are the standard mapping reference for scientists, land managers, property owners, and every variety of outdoor enthusiasts. So I am very pleased that this new type of USGS topographic map not only preserves the best qualities of older topographic maps but now, in a popular digital format, can better serve both specialised users and the general public.”

Arranged in the familiar 7.5-minute quadrangle format, US Topo maps are available free on the Web. Each map quadrangle is constructed in GeoPDF format from key layers of geographic data — orthoimagery, roads, geographic names, topographic contours, and hydrographic features — found in The National Map, a nationwide collection of integrated data from local, state, federal, and other sources.

“These digital maps can be as simple or as sophisticated as the need dictates, easily customised on the spot”, said USGS Director Marcia McNutt.

US Topo users can turn geographic data layers on and off as needed, zoom in and out to highlight specific features or see a broader context, and print the maps — in their entirety or in customised sections — on a wide variety of printing devices. File size for each digital US Topo 7.5-minute quadrangle, about 15-20 megabytes, is convenient for most computer users. Electronic analytical tools are also available for free download.

Mark DeMulder, Chief of the USGS National Geospatial Program said “Here is how US Topo differs from most other electronic maps:

- Nationally consistent data quality assured to high standards
- Looks and feels like legacy paper USGS topographic maps but has technical advantages
- Can be used on the computer or printed to scale
- Down loadable free from the on-line USGS Store
- Users can select from various reference systems, e.g lat-long, UTM (Universal Transverse Mercator)
- Direct “mash-up” capabilities with Google Maps
- Continuous evolution and incorporation of additional data layers.”

Further information about how to download and use US Topo, currently available coverage, and the timetable for production of US Topo maps can be found online at: nationalmap.usgs.gov/ustopo.

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