Frequently Asked Questions

Mapping, Remote Sensing, and Geospatial Data

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

Filter Total Items: 213
Crop of Landsat 7 Path 38 Row 35, Acquired March 29, 2013
Landsat 7 ETM+ SLC-off data refers to all Landsat 7 images collected after May 31, 2003, when the Scan Line Corrector (SLC) failed. These products have data gaps, but are still useful and maintain the same radiometric and geometric corrections as data collected prior to the SLC failure. See the Landsat 7 website for information about the SLC-off...
Landsat image showing scar marks from fire in comparison to ASTER.
Data acquisition requests are not available to the public. The Landsat 8 and Landsat 7 satellites each acquire data on a continual basis in accordance with their respective Long Term Acquisitions Plans. The Landsat Acquisitions page has calendars and information about daily schedules. Learn more: Landsat 8 Long Term Acquisitions Plan Landsat 7...
Image shows aerial imagery of flooding in Louisiana, courtesy of the National Geodetic Survey
Remote sensing is the process of detecting and monitoring the physical characteristics of an area by measuring its reflected and emitted radiation at a distance (typically from satellite or aircraft). Special cameras collect remotely sensed images, which help researchers "sense" things about the Earth. Some examples are: Cameras on satellites and...
Lidar image of Pittsburgh
Lidar data are available through: The 3DEP LidarExplorer Application.  The National Map Downloader. Click the “Help” link at the top of the viewer for detailed instructions on how to find and download data.  Select "Custom Views > Elevation" to display elevation data options only. Light Detection and Ranging (LIDAR) is a technology similar to...
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