Quality Assessment (QA) bands are a helpful resource for evaluating the overall usefulness of a Landsat pixel. Each pixel in the QA band contains an integer value that represents bit packed combinations of surface, atmospheric, and sensor conditions that can affect the individual pixel quality. QA bands are currently provided with Collection 1 based products, including Landsat Level-1 Data Products and Landsat Science Data Products.
The already-established Landsat Quality Assessment (QA) Tools provide the functionality of extracting bit packed values to individual bands for only the Landsat Level-1 BQA band; this ArcGIS-based toolbox provides functionality to classify and/or extract bit packed values for all Level-1 and Science Data Product QA bands.
The Landsat QA ArcGIS Toolbox is compatible with all Landsat Collection 1 Level-1 and Science Data Product QA bands. The table below describes each band’s properties.
|Level-1||Level-1 Product||Landsat Collection 1 Level-1 Quality Assessment Band|
|Science Data||TOA, SI, SR||Landsat Surface Reflectance Quality Assessment|
|TOA, SI, SR|
|Landsat 4-7 SR (LEDAPS)|
|Landsat 8 SR (LaSRC)|
BQA Level-1 Quality Assessment Band File, LaSRC Landsat Surface Reflectance Code, LEDAPS Landsat Ecosystem Disturbance Adaptive Processing System, SI Spectral Indices, SR Surface Reflectance, TOA Top of Atmosphere Reflectance
Download Landsat QA ArcGIS Toolbox
The Landsat QA ArcGIS Toolbox provides functionality to classify and/or extract bit packed values for all Level-1 and Science Data Product QA bands, which are listed in the table below. The use of this tool enhances the applications of interpretation, mapping and applying QA values to all Landsat data products.
The Landsat QA ArcGIS Toolbox includes the following tools:
Decode QA – decodes bit-packed quality information from Landsat Level-1 and Science Data Product QA bands. Unlike bit-unpacking tools, Decode does not generate new bands, but instead builds an attribute table from the input and populates each unique value with its respective classification.
Extract QA Bands – finds all unique values in the QA band, and extracts classes individually, as defined by user input. The tool then writes each class to a new image file, and provides the option to combine all selected classes into a single file.
The Landsat QA ArcGIS Toolbox README file contains installation instructions and all pertinent details for each tool.
The toolbox was designed using ArcGIS version 10.4.1 and Python version 2.7.10. The functionality of the toolbox cannot be guaranteed for previous software versions, and cross-compatibility of newer and future ArcGIS and Python releases are subject to vendor discretion. Other caveats include:
- Input data must be in GeoTIFF (.tif), binary (.img), or other single-band raster format supported by ArcGIS.
- Input data must be stored in integer format; any float, double, or complex data types are not supported.
- Any band with values outside of the supported range will not process.
- If using non-standard (i.e., user modified) file naming conventions, the tool may not correctly identify the band type, which may result in incorrect output products. Ensure the “sensor” and “band” categories are set accordingly.
Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.