USGS Frequently Asked Questions
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- Are the scanned aerial photographic images georectified?
Scanned products are not georectified. If a customer needs them georectified they will have to do the registration themselves or have that process performed by a provider of value added services. ... - Are there any restrictions on using the trademarked National Atlas data and maps?
No, not usually. Nearly all information collected by the Federal Government is in the public domain and use of raw data produced for the National Atlas is not restricted in any way. Both 'National Atlas of the United States' and 'The National A... - Do you have map data in digital form?
YES. Visit our Digital Geospatial Data Page or call 1-888-ASK-USGS for our information package on digital cartographic data. ... - Does the National Elevation Dataset (NED) replace any of the existing USGS Digital Elevation Model (DEM) products?
No. The USGS DEMs and other digital elevation data that were used as source data in building NED will continue to be available from the USGS and those of its business partners that resell digital data.... - How accurate is the elevation data in the Geographic Names Information System Database? How was it measured?
The elevation data in GNIS are not official.Only the geographic name and locative attributes are official. The elevation data are from the National Elevation Dataset of the U.S. Geological Survey for the primary location of the feature (Coordinates Seque... - How are different map projections used?
Every flat map misrepresents the surface of the Earth in some way. No map can rival a globe in truly representing the surface of the entire Earth. However, a map or parts of a map can show one or more - but never all - of the following: True directions. Tr... - How are UTM coordinates measured on a USGS topographic quadrangle map?
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 coord... - How can I clip the map collar off my digital raster graphic (DRG)?
UNIX ONLY:A set of ARC Macro Language (AML) programs and C source are available at http://thor-f5.er.usgs.gov/drg/clip A couple of problems arise with the clipping. Because of the map angle, sliver areas (areas with no data) are created when the collar is ... - How can I convert USGS Digital Elevation Models (DEMs) to XYZ triples?
MICRODEM is a free software package with a built-in DEM converter. MICRODEM is available at www.usna.edu/Users/oceano/pguth/website/microdem/microdem.htmIt requires a 32 bit version of Windows (NT/2000/XP or 95/98/ME). Software packages that will... - How can I determine the UTM zone of my digital orthophoto quadrangle (DOQ)?
The UTM zone is indicated in the DOQ header. See the sample DOQ header for more information. NEW FORMAT DOQ HEADER BEGIN_USGS_DOQ_HEADER *QUADRANGLE_NAME 'SAN FRANCISCO NORTH' ... - How can I find digital map data?
There are several different sources available and dependent on the type of information you are searching for: Digital Map Data Product Search or Order DEM Digital Elevation Model http://edc.usgs.gov/geodata/http://seamless.usgs.go... - How can I find survey benchmark information?
Most survey benchmarks were not established by the U.S. Geological Survey (USGS), but by the National Coast and Geodetic Survey, and are available on the web from http://www.ngs.noaa.gov ['Data sheets']. For further assistance call 301-713-3242 or ... - How can I get DLG data into AutoCAD?
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. DLGTODX... - How can I reproject USGS data?
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 error ... - How can I view a USGS Digital Line Graph (DLG)?
dlgv32pro - FREE Windows program. Written at Mid-Continent Mapping Center (MCMC). Feedback!!!!!! Address all questions and comments about dlgv32 to mcmcesic@usgs.gov ARC/INFO (including attributes) ERDAS Imagine (creates ARC/INFO coverages. UNIX vers... - How can I view a USGS digital orthophoto quadrangle (DOQ)?
DLGv32pro FREE - available at http://mcmcweb.er.usgs.gov/drc/dlgv32pro/. Paint Shop Pro version 4.12 (shareware) will read both JPEG and uncompressed (.raw) gray-scale images. Use the raw format option for loading uncompressed DOQs. Paint Shop Pro is a... - How can I view USGS digital raster graphics (DRGs)?
Depending on a users needs, various viewers and other software are capable of importing a DRG. Factors for determining what software to use include intended usage, cost, and especially the ability to read a TIFF 6.0 image . Listed below are a few types of ... - How current will the "Digital Map - Beta" be?
These maps will be remade every three years as the U.S. Department of Agriculture's National Agricultural Imagery Program (NAIP) aerial imagery is reflown and new Digital Orthophoto Quadrangles (DOQ) are made. The features shown on the maps will be rev... - How do I get files off the county digital orthophoto quadrangle (DOQ) CD-ROM?
A program (with a menu interface) to extract DOQs from a CD-ROM is provided with the data. At a DOS prompt, type DOQ and follow the instructions. File-naming convention seems to be a problem in this process. The menu interface allows users to pick which ... - How do I get more detailed information about the National Atlas?
There are several ways to get more detailed information than what you find in the National Atlas. First, National Atlas raw data come from many different Federal agencies and these agencies are often the best sources for more detailed information. Link... - How do I report a geographic position?
If coordinates are to be passed on to another person it is technically necessary to report the horizontal datum and the latitude/longitude of the point (e.g. NAD 27 CONUS, 44 degrees, 7 minutes, 30 seconds north/ 104 degrees, 15 minutes, 10 seconds west). ... - How does USGS produce a digital orthophoto quadrangle (DOQ)?
The following items are required to produce a digital orthophoto: a minimum of three ground positions that can be identified on the photograph to be rectified, camera calibration parameters, such as the calibrated focal length and the coordinates of t... - How is the State Plane Coordinate system set up? Can GPS provide coordinates in these values? What about Public Land Survey System (PLSS) readouts?
The State Plane Coordinate System (SPCS) is a plane coordinate system (N-S and E-W lines are perpendicular) in which each individual state has from one to six zones, depending on the state's size and shape. The grid system in some states is based on th... - How large is the North American Datum (NAD) 27 to NAD 83 shift?
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 at ... - How much distance does a degree, minute and second cover on your maps?
The distances vary. A degree, minute or second of latitude remains fairly constant from the equator to the poles; however a degree, minute, or second of longitude can vary greatly as one approaches the poles (because of the convergence of the meridians). A...