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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Traditional Universal Transverse Mercator (UTM) convention distinguishes between the Northern and Southern Hemispheres. In the Northern Hemisphere, the UTM zone is a positive value or identified as UTM North. In the Southern Hemisphere, the UTM zone is a negative value or identified as UTM South. UTM North scenes in this convention have a false...
Landsat data products held in the USGS archives can be searched and downloaded at no charge from a variety of sources. Visit the Landsat Data Access web page for information about how Landsat data products can be downloaded individually or in bulk.
Landsat imagery not found in the USGS archive might have been collected by one of the USGS...
Landsat 8's Band 9 1.360-1.390 µm detects thin, high-altitude clouds composed of ice crystals that might not be visible in other spectral bands. In Band 9, cirrus clouds appear bright while most land surfaces appear dark through an otherwise cloud-free atmosphere containing water vapor.
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Landsat 8 Mission
Landsat 8 bands (NASA)
Landsat...
Landsat 8’s Band 1 (0.433-0.453 µm) is useful for imaging shallow water and tracking fine atmospheric particles like dust and smoke.
Since water absorbs and scatters light, oceans and lakes tend to look dark or lack detail on satellite images, especially in the sediment-laden waters near coastlines. Band 1 reflects blues and violets and displays...
The first indication you have data processed meeting Collections specifications is that your data will have a Landsat Product Identifier, not the historical Landsat Scene ID. Along with information inherited from the Scene ID, the Landsat Product Identifier includes the processing level, processing date, collection number, and collection category...
The file sizes of Landsat Collection 1 Level-1 data products are listed in the table below.
Sensor
Compressedfile
Uncompressedfile
Landsat 8 OLI/TIRS
919 MB
1.61 GB
Landsat 7 ETM+
235 MB
785 MB
Landsat 4-5 TM
150 MB
500 MB
Landsat 1-5 MSS
20 MB
75 MB
Landsat Collections Real-Time (RT) data provide temporary data within 12 hours of acquisition in support of the International Charter to help mitigate the effects of disasters on human life and property.
The RT tier contains data received from Landsat 8 and Landsat 7 immediately after acquisition. Estimated radiometric and geometric calibration...
Landsat Collection Tiers are the inventory structure for Level-1 data products and are based on data quality and level of processing. The tier definition purpose is to support easier identification of suitable scenes for time-series pixel-level analysis, and provide temporary data that are processed immediately upon downlink to be dispensed...
In 2016, the USGS reorganized the Landsat archive into a tiered collection. This structure ensures that Landsat Level-1 products provide a consistent archive of known data quality to support time-series analyses and data “stacking”, while controlling continuous improvement of the archive and access to all data as they are acquired.
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The Verify Image (_VER.jpg) and Geometric Verify Report (_VER.txt) files are included with Landsat MSS and TM Collection 1 Level-1 scenes that have processed into Tier 1.
The Verify Image File displays a colored grid of verification points to represent the accuracy of geometric correction, using cross-correlation techniques to compare the product...
The sensors aboard each of the Landsat satellites were designed to acquire data in different ranges of frequencies along the electromagnetic spectrum (View Bandpass Wavelengths for all Landsat Sensors). The Multispectral Scanner (MSS) carried on Landsat 1,2,3,4 and 5 collected data in four ranges (bands); the Thematic Mapper (TM) sensor on Landsat...
In order to obtain a "seamless" mosaic, radiance (and preferably reflectance) might need to be calculated before performing the mosaic because gain changes might occur in one or more of the scenes. When two scenes have different gain states, they have different dynamic ranges and there will be a shift in Digital Number (DN) values from one scene...