Science Technology

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 quickly in emergency response situations with limited...

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 Collections Landsat Data Access

The Verify Image (_VER.jpg) and Geometric Verify Report (_VER.txt) files are included with Landsat Multispectral Scanner (MSS) and Thematic Mapper (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 to the...

The sensors onboard each of the Landsat satellites were designed to acquire data in different wavelengths in 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 4 and Landsat 5 included those bands found on earlier satellites...

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 to the next. This can be determined by reviewing the...

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 reflectance products. Learn more Landsat Surface...

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 January 1986 and December 1999, originally...

Black browse images are night (ascending) scenes, which are occasionally acquired for WRS-2 rows 123 to 246. Ascending scenes are available to download. Learn more: How to search and download ascending Landsat scenes

The C Function of Mask (CFMask) algorithm is used in Landsat Collection 1 Level-1 data processing. This algorithm provides a full-image “Scene Cloud Cover” estimation of the percentage of cloud cover calculated over an entire Landsat scene. Land Cloud Cover, which is also included, is determined by calculating the percentage of clouds over land-only pixels in a scene using a mask that...

Band-specific gap mask files are included with every Landsat 7 Scan Line Corrector (SLC)-off Level-1 data product. These ancillary data identify the location of all pixels affected by the original data gaps in the primary SLC-off scene. The gap mask is provided as a series of individual band files, in compressed (GZIP) GeoTIFF format. Gap Mask Legend Values: green = primary scene blue = fill scene...

Landsat 7 acquires thermal data in two bands from one detector in both high (Band 6H) and low (Band 6L) gain. The difference in gain settings is important to different types of studies (i.e., clouds vs. deserts). Aside from the resolution differences and saturation on the high and low ends, the two bands provide the same Digital Numbers (DN) for every pixel. FILE_NAME_BAND_6_VCID_1 (band 61 or 6L)...

The Worldwide Reference System (WRS) is a global system that catalogs Landsat data by Path and Row numbers. Landsat satellites 1, 2 and 3 followed WRS-1, and Landsat satellites 4,5,7, 8, and 9 follow WRS-2. Learn more: Landsat Path Row Shapefiles and KML Files The Worldwide Reference System (NASA)