This document provides an overview of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) supplemental algorithms in conjunction with the reuse of Landsat geometric algorithms modified by the National Aeronautics and Space Administration (NASA Land Processes Distributed Active Archive Center (LP DAAC) to create an ASTER Level 1 Precision Terrain Corrected Registered At-Sensor Radiance (AST_L1T) product. Implementation of these algorithms occurs within the AST_L1T product generation executable (PGE) as part of the open source Simple, Scalable, Script-based Science Processor for Missions (S4PM) processing software subsystem.
The AST_L1T algorithms include the following:
- Generation of the AST_L1A input product via supplemental algorithms
- Application of the radiometric and geometric corrections appended in the AST_L1A product
- Application of cross-talk correction coefficients
- Generation and application of affine transformation coefficients
- Modification and reuse of Landsat’s geometric algorithms including:
- Systematic—generates the systematic grid
- Resampling—multi-use; only a single resample of input scene
- Gpyramid—scale input image to reference image (if necessary)
- Ground Control Point (GCP) Correlate—computes x,y offsets for GCPs to be used for precision grid generation
- Precision Refine—generates the precision grid
- GVERIFY—geometric verification
