Landsat Missions

Landsat Processing Systems

Landsat Collection 1 Level-1 data products are produced by the Landsat Product Generation System (LPGS). LPGS also generates the 16-bit Quality Assessment Band (QA) and an angle coefficient file that are included in the Level-1 product, as well as a Full Resolution Browse (FRB) and an 8-bit Quality Image. The system then delivers the data products and images to  the online cache for distribution. 

Access Landat Level-1 Processing Details

 

Data Exempt from LPGS Processing

Some Landsat 4-5 Thematic Mapper (TM) data acquired between 1984 and 1989 cannot be processed by LPGS and added to the Collection 1 Level-1 dataset. Instead, these scenes were processed by the National Land Archive Production System (NLAPS), which was the original Landsat processing system prior to implementing LPGS when Landsat 7 data became available in 1999. Information describing NLAPS data compares to the current LPGS-processed data is provided below. 

Download Landsat 4-5 TM NLAPS scene list

These scenes will be added to EarthExplorer's Landsat Legacy datasets in the future and will become available to download as is

LPGS vs NLAPS Processing Systems: Similarities and Differences

While one similarity exists, the NLAPS and LPGS processing systems have unique charcteristics that users must be aware of when comparing data from each system: 

Similarities

Pixel Alignment: For each scene, Landsat spectral bands are aligned to a common center 1,1 / X,Y location for each pixel. (The pixel centers are aligned but the edges are not.) The X,Y center location is noted in each scene's metadata file.

Differences

Resampling Methods: NLAPS and LPGS use different ephemeris files and different algorithms to process quaternion, gyro, and gyro drift data. This may cause some slight additional differences when comparing the data. 

Data Format: while both NLAPS and LPGS have the 'BitsPerSample' tag set to 8 within the GeoTIFF file header, NLAPS has the SampleFormat tag set to unsigned integer format. LPGS does not use the SampleFormat tag in its GeoTIFF products, even though they are also unsigned integer format.

Gimbaled X-Band Antenna (GXA) Slewing Anomalies: GXA anomalies appear as scan line offsets or extensions and can occur when the GXA redirects itself from one ground station to another, and Level-1 processing may correct this problem in some instances. LPGS estimates an 'End-of-Line' (EOL) and processes the scans with that estimated number. NLAPS defines no EOL as 'no data,' and zero-fills the affected scans.

Metadata files:  LPGS-processed Landsat Collection 1 Level-1 data products include a metadata (MTL.txt) file; data processed by NLAPS include a Work Order (WO.txt) fiel that contains the scene metadata.