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Rajagopalan Rengarajan

Publications and source records attributed to Rajagopalan Rengarajan.

4 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2023

The 50-Year Landsat Collection 2 Archive

The Landsat global consolidated data archive now exceeds 50 years. In recognition of the need for consistently processed data across the Landsat satellite series, the U.S. Geological Survey (USGS) initiated collection-based processing of the entire archive that was processed as Collection 1 in 2016. In preparation for the data from the now successfully launched Landsat 9, the USGS reprocessed the Landsat archive as Collection 2 in 2020. This paper describes the rationale for, and the contents and advancements provided by Collection 2, and highlights the differences between the Collection 1 and Collection 2 products. Notably, the Collection 2 products have improved geolocation and, for the first time, the USGS provides a global inventory of Level 2 surface reflectance and surface temperature products. Also for the first time, the USGS used a commercial cloud computing architecture to efficiently process the archive and enable direct cloud access of the Landsat products. The paper concludes with discussion of likely improvements expected in Collection 3 in preparation for the Landsat Next mission that is planned for launch in the early 2030s.

Christopher J Crawford↗
NASA NTRS2021

The New Landsat Global Land Survey (GLS) DEM

The Landsat project, for its Collection 2 distribution, is going to introduce a new global Digital Elevation Model (DEM) for scene orthorectification. The new global DEM is a composite of the latest and greatest available DEM sources and will include reprocessed SRTM (called NASADEM), hi-resolution stereo optical data (ArcticDEM), and various nationally produced datasets. With exception of a few places, most of the world will have the updated DEM, with improvements in absolute vertical accuracy and horizontal improvements of up to 360 meters (12 Landsat 30m pixels). This new DEM will be used to process all the scenes from Landsat 1-8 in Collection 2 processing and will be made available to public in Summer 2020.

Landsat↗
NASA NTRS2020

The New Landsat Collection-2 Digital Elevation Model

The Landsat Collection-2 distribution introduces a new global Digital Elevation Model (DEM) for scene orthorectification. The new global DEM is a composite of the latest and most accurate freely available DEM sources and will include reprocessed Shuttle Radar Topographic Mission (SRTM) data (called NASADEM), high-resolution stereo optical data (ArcticDEM), a new National Elevation Dataset(NED) and various publicly available national datasets including the Canadian Digital Elevation Model (CDEM) and DEMs for Sweden, Norway and Finland (SNF). The new DEM will be available world-wide with few exceptions. It is anticipated that the transition from theCollection-1 DEM at 3 arcsecond to the new DEM will be seamless because processing methods to maintain a seamless transition were employed, void filling techniques were used, where persistent gaps were found, and the pixel spacing is the same between the two collections. Improvements to the vertical accuracy were realized by differencing accuracies of other elevation datasets to the new DEM. The greatest improvement occurred where ArcticDEM data were used, where an improvement of 35 meters was measured. By using theses improved vertical values in a line of sight algorithm, horizonta improvements were noted in some of the most mountainous regions over multiple 30-meter Landsat pixels. This new DEM will be used to process all of the scenes from Landsat 1-8 in Collection-2 processing and will be made available to the public by the end of 2020.

Shannon Franks↗