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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Algal bloom off the coast of Brazil, Landsat 2017 image
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...
Earth As Art image of the Beni River in Bolivia
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...
Canyonlands National Park as seen by Landsat 8
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 image of flooding along Missouri River from March 2019
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 8 image
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...
Landsat Collections Fact Sheet
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. Learn more:...
Landsat Geometric Verify Image
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...
Land of Terror - Earth As Art image of Algeria
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...
color photo of South Dakota state mosaic puzzle
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...
Cape Town, False Bay, South Africa
Landsat atmospheric correction and surface reflectance retrieval algorithms are not ideal for water bodies due to the inherently low surface reflectance of water. Similarly, surface reflectance values greater than 1.0 can be encountered over bright targets such as snow and playas. These are known computational artifacts in the Landsat surface...
Landsat TM No-Payload Correction Data Example
Payload Correction Data (PCD) provides critical information when correcting for geometric distortions inherent to the imaging system and temperature values used to estimate per-scan gains and biases necessary for the radiometric calibration of the instrument's thermal band data. Over 260,000 Landsat 5 Thematic Mapper (TM) scenes acquired between...
Earth at night.
Black browse images are night (ascending) scenes, which are occasionally acquired for WRS-2 rows 123 to 246. Ascending scenes are available to download; see this FAQ for more information on searching and downloading ascending scenes.