Frequently Asked Questions

Mapping, Remote Sensing, and Geospatial Data

The USGS provides the mapping and digital geospatial foundation for the Nation.

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Lidar image
Yes, lidar data are represented as a cloud of variably spaced point locations (x,y,z) of any terrestrial target reflecting the laser pulse. In addition to bare-earth, the point cloud will typically include buildings, trees, towers, and powerlines. 3DEP DEMs are raster surfaces of bare-earth elevation values sampled at uniform horizontal increments...
Example visualization of model output
If you think you’ve found an error please send an e-mail to tnm_help@usgs.gov.  We will add the reported information to our "Digital Elevation Model Issues" data log for further analysis and possible correction. Spikes, pits, seam-line anomalies, and other data errors or blunders are of concern to us, and we are working to correct or minimize...
Screen shot of ScienceCache mobile application's map interface.
Data from The National Map (TNM) can be used in mobile applications through MOBAC, the Mobile Atlas Creator. MOBAC is a desktop (not mobile) application that will build local map caches of USGS TNM data for handheld devices, such as mobile Android phones, iPhones (iOS), and GPS. It works with the AlpineQuest, and TerraGo Edge applications for...
3D Lidar Point Cloud of the United States Capitol Building
The U.S. Geological Survey (USGS) is committed to making its websites accessible to all users in accordance with provisions of Section 508 of the Rehabilitation Act of 1973 (as amended in 1998). Currently, there is no technology capable of producing alternatives to dynamically generated geospatial images in The National Map viewer or download...
The National Map Viewer Interface
International users should first set their Internet browser language to "English (United States)" to be able to access The National Map viewer.  Internet Explorer users might also need to clear their browser history and use Ctrl-F5 to refresh the cache. If Internet Explorer still doesn’t work, try using a different browser. Internet Explorer might...
The National Map Logo
Map services and data downloaded from The National Map are free and in the public domain. There are no restrictions; however, we request that the following acknowledgment statement of the originating agency be included in products and data derived from our map services when citing, copying, or reprinting: "Map services and data available from U.S...
TNMCorp250x250
Visit our API Examples Demos Web page for TNM services being used in other Application Program Interfaces (APIs), such as Leaflet, OpenLayers 2, Google Earth, and OpenLayers 3 Mobile. Other examples include usage of the Elevation Point Query Service (EPQS) and an Arctic Spatial Data Infrastructure (SDI) viewer.
Screen shot of streams near the Dillon Reservoir, Frisco, CO on imagery basemap
A complete list of service URLs can be found at The National Map-Service Endpoints website, which contains available REST, WMS, WMTS (cached base maps only), WFS, WCS, and other service links.
Screen shot of the Topo TNM Style Template customized to the Park Place, Texas 7.5-minute Quadrangle
The "Error: Inventory request failure" message occurs if our ScienceBase catalog database is not responding to download requests. To ensure data integrity, the Science Base catalog is shut down for nightly backup at 11:00 pm Mountain time, which takes 1-2 hours. If you find that the message is still occurring even after the allotted two hours,...
A multicolored lidar image of the Great Sand Dunes
If you use the Mozilla Thunderbird email client, download links through an 'ftp' protocol might return empty files. The work-around is a procedure to associate ftp links in Thunderbird with a Web browser (such as Chrome), which then allows links to open and correctly download. Use this procedure at your own discretion:  Open the Thunderbird...
National Map Viewer
Yes, direct access is provided via browsable links through our FTP Server and Amazon's Cloud. Navigate to the appropriate theme folders to access staged products for download.
Landsat satellite dish inside radome at USGS EROS
An error that times out the Web browser can sometimes occur after clicking on a download link. You might be able to open the archive (.zip) file by refreshing your screen. In the case of an incomplete download, first clear your browser history to avoid the cache interfering with subsequent future attempts. Then use Ctrl+F5 keys to refresh the...