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 of Pittsburgh
Lidar data are available through The National Map Download Client. Click the “How To” link at the top of the viewer for detailed instructions on how to find and download data.   Light Detection and Ranging (LIDAR) is a technology similar to RADAR that can be used to create high-resolution digital elevation models (DEMs) with vertical accuracy as...
Aerial photo of Anvil Lake
Yes, there is a plan to scan and digitize all rolls of film. The plan is to first scan all rolls of film that are in danger of decay from vinegar syndrome and then scan everything else. Science and customer requirements are also reviewed on a regular basis, but a formal, online schedule is not available. Learn more: USGS EROS products overview...
USGS air photo of the Mud Creek landslide, taken on May 27, 2017
The U.S. Geological Survey (USGS) Earth Resources Observation and Science Center (EROS) can only certify that the product downloaded through our website is an authentic reproduction of an official record of the government that is in the legal custody of the USGS EROS. See the standard Authenticity of Digital Imagery document.
Orthoimagery of the Maryland State House, Annapolis, Maryland
The ability to see specific items in an aerial image is mostly a function of scale and resolution. The following aerial photography products all have a resolution of 1 meter or better, so you should be able to see an object the size of a house:  High Resolution Orthoimagery (HRO) National Agriculture Imagery Program (NAIP) imagery Digital...
PASA.Landsat image - Great Salt Desert - Iran - small and cropped.jpg
Many image processing programs (ERDAS IMAGINE®, PCI Geomatica®, ENVI®, IDRISI®, etc.)* can import a variety of image formats, including the GeoTIFF files of Landsat data. Free Multispec software that is included with the USGS lesson plan Tracking Change Over Time can be used for limited spectral analysis. To view Landsat scenes without using...
Example of Scan Mirror Anomaly in Landsat 7 ETM+ browse image.
A number of artifacts and anomalies can happen to any remote sensing data. Banding, dropped scan lines, and detector failures are only a few of the anomalies that can be seen in Landsat data. Go to Landsat Known Issues for details about anomalies that have been discovered and investigated.
Image shows a satellite view of wildfire damage in Argentina
A custom color stretch is performed on the images, based on individual scene content. Scenes from within the same area and/or acquisition date might vary in band content (due to differences such as cloud content or ground moisture). This differing content will cause variation in the results of the color stretch.   Pixelation is an artifact of the...
Chesapeake Bay 2014 Landsat imagery
Landsat scenes directly downlinked to the USGS EROS Landsat Ground Station become available through EarthExplorer within 6 hours after acquisition, and then become visible in GloVis and the LandsatLook Viewer within 24 hours. Scenes downlinked to other USGS Ground Stations can be available within 1 to 2 weeks. Scenes downlinked to International...
Kaskawulsh Glacier, Yukon Territory, Canada, Landsat 8, taken July 4, 2016
There are no restrictions on Landsat data downloaded from the USGS; it can be used or redistributed as desired. We do request that you include a statement of the data source when citing, copying, or reprinting USGS Landsat data or images. Details are on the EROS Data Citation page. Learn more: USGS Copyrights and Credits statement  
Landsat Imagery
The Landsat Program is a series of Earth-observing satellite missions jointly managed by NASA and the U.S. Geological Survey. On July 23, 1972, in cooperation with NASA, the Earth Resources Technology Satellite (ERTS-1) was launched. It was later renamed Landsat 1. Additional Landsat satellites followed in the 1970s and 1980s. Landsat 7 was...
The Bumble Bee, Arizona US Topo map
Yes, depression contours are identified with tick marks, but only in large scale contours from 36K to 18K.
Improved Topo Base map of the Glacier Peak WA area
The 500-foot contours are shown at a scale of 578K in base maps, while 100-foot contours are visible at 289K/144K and 50-foot contours are visible at 72K.  Large scale contours from US Topo products are shown from 36K to 18K, and in dynamic base map services for scales larger than 18K.