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The USGS is offering standard data products from the entire Landsat archive to all users at no charge. While most Landsat scenes are processed with the Standard Terrain Correction (Level 1T), some scenes do not have the ground-control or elevation data necessary to perform these corrections. In these cases, the best level of correction is applied. (See the box below for details on the levels of correction.)
Additionally, most archived Landsat 1–5 MSS scenes, as well as a select number of Landsat 4–5 TM scenes, are processed with only Systematic Correction (Level 1G) due to processing constraints. Improvements to production capabilities are being investigated and, when employed, will allow more scenes to be processed at a higher correction level with a shorter processing time.
The processing level of a downloaded scene is located in the metadata (MTL.txt) file or processing history (WO.txt) file; these are delivered with the data band files and other ancillary data. For more information, please refer to this FAQ.
Landsat7 data level:
Standard Terrain Correction (Level 1T) - provides systematic radiometric and geometric accuracy by incorporating ground control points while employing a Digital Elevation Model (DEM) for topographic accuracy. Geodetic accuracy of the product depends on the accuracy of the ground control points and the resolution of the DEM used:
Systematic Terrain Correction (Level 1Gt) - provides systematic, radiometric, and geometric accuracy, while employing a Digital Elevation Model (DEM) for topographic accuracy.
Systematic Correction (Level 1G) - provides systematic radiometric and geometric accuracy, which is derived from data collected by the sensor and spacecraft. Geometric accuracy of the systematically corrected product should be within 250 meters (1 sigma) for low-relief areas at sea level.
Landsat data product details:
Landsat 7 Enhanced Thematic Mapper Plus (ETM+) - a sensor carried onboard the Landsat 7 satellite since July 1999 with a 16-day repeat cycle.
Landsat 4-5 Thematic Mapper (TM) - a sensor carried onboard both Landsat 4 and Landsat 5 since July 1982 with a 16-day repeat cycle.
Landsat 1-5 Multispectral Scanner (MSS) - a sensor carried onboard Landsats 1-3 from July 1972 to March 1983 with an 18-day repeat cycle, and onboard Landsats 4 and 5 from July 1982 to October 1992 with a 16-day repeat cycle.
Remotely Sensed Data Collections: Offerings from EROS - .pdf (1.24 MB) - this fact sheet highlights eight remotely sensed data collections that are currently available from EROS.
How do I determine the processing level of the Landsat scene I have downloaded?Answer:
The processing level* of a downloaded scene can be found in either the metadata (MTL.txt) or processing history (WO.txt) files. These files are delivered with the data band files and other ancillary data.
The MTL.txt file is included when a scene is processed through the Level 1 Product Generation System (LPGS). All Landsat 7 ETM+ (1999 -present), most Landsat 4-5 TM (1982 -present) and all Landsat MSS 1-5 (1972-1983) scenes are processed through LPGS.
The WO.txt file is included when a scene is processed through the National Land Archive Production System (NLAPS). Some Landsat 4-5 TM (1982-1990) scenes are processed through NLAPS.
*Descriptions of processing levels can be found at http://landsat.usgs.gov/products_productinformation.php
After downloading the scene, locate and open the MTL.txt file or the WO.txt file.
Within the MTL.txt file, the processing level is listed as PRODUCT TYPE, as seen in the example below. L1T designates terrain corrected processing. L1Gt designates systematic terrain corrected processing. L1Gdesignates systematic corrected processing.
Figure 1. MTL.txt Example
Within the WO.txt file, the processing level is listed as Processing Level, as seen in the example below. Precision Geocorrection designates terrain corrected processing, similar to L1T processing listed in the MTL.txt example listed above. Systematic Geocorrection designates systematic corrected processing.
Figure 2. WO.txt Example
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