Geospatial

UTM coordinates are measured on the map by subdividing the 1000 meter grid squares into tenths or hundredths. This will narrow down the coordinate to a 100 or 10 meter square. Usually the measurements are made using a simple mylar or paper scale or a...
Generally, for the conterminous United States, the North American Datum (NAD) shift amounts to about 210 meters. This shift occurs because of the change in shape of the spheroid used to define the datum. The GRS 80 spheroid (used for NAD 83) is shorter...
An exhaustive database that provides bibliographic access to thousands of geologic, geophysical, and other kinds of maps available in USGS publications, Web sites, and in popular science journals.
No. A photographic enlargement only appears to show more detail than a 9-by-9 inch photograph. Photographic resolution (or image resolution) deteriorates with each enlargement factor.Photographic reproduction of images from the USGS film archives ceased...
YES, Visit our National Geospatial Program page or call 1-888-ASK-USGS for our information package on digital cartographic data. 
MICRODEM is a free software package with a built-in DEM converter. It requires a 32 bit version of Windows (NT/2000/XP or 95/98/ME).Software packages that will read DEMs:ARC/INFO (grid module)PCI (will only import 30-meter USGS DEMs)ERDAS...
USGS DLG files must be translated into DXF before AutoCAD can read the files. Here is one way this can be accomplished:Download a DLG to DXF converter. There are different versions of this program depending on the version of AutoCAD.DLGTODXF - for...
About 180,000 USGS historical topographic maps (more than 95% of those ever published) are available to the public free of charge, and the number of maps available is still growing. This set of GeoPDF files is referred to as the Historical Topographic...
That depends on what kind of reprojection you want to do. In some cases, if you want to reproject from one datum to another (specifically NAD 27 to NAD 83 or NAD 83 to NAD 27), a simple xy shift will suffice. This shift will not introduce measurable...
It will probably take approximately 5 years to digitize the archive. A priority scheme is being developed and will be made available to the public at a later date.