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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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...
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...
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 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...
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...
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.
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...
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...
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.
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...
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...
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