Σάββατο, 5 Νοεμβρίου 2011

METI and NASA Release Version 2 ASTER Global DEM

The version 2 collection of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Global Digital Elevation Model (GDEM) was released jointly October 17, 2011 by the Ministry of Economy, Trade, and Industry (METI) of Japan and the United States National Aeronautics and Space Administration (NASA). As with Version 1, METI and NASA are contributing the ASTER GDEM to the Global Earth Observation System of Systems (GEOSS). Consequently, the ASTER GDEM is available at no charge to users worldwide via electronic download from the Earth Remote Sensing Data Analysis Center (ERSDAC) of Japan and from NASA’s Land Processes Distributed Active Archive Center (LP DAAC).


ASTER, on the NASA spacecraft Terra, is capable of collecting in-track stereo using nadir- and aft- looking near infrared cameras. Since 2001, these stereo pairs have been used to produce single-scene digital elevation models (DEM). The best quality data from the DEM record were compiled globally to generate the ASTER GDEM 2.

Version 2 is produced with the same gridding and tile structure as Version 1. Extensive validation of GDEM 2 noted substantial improvements in product quality due specifically to the increased number of acquired ASTER stereo pairs and refinements to the production algorithm (water masking, smaller correlation kernel size, bias removal). These improvements include increased horizontal and vertical accuracy, better horizontal resolution, reduced presence of artifacts, and more realistic values over water bodies.

Users are nonetheless advised that the products still may contain anomalies and artifacts that will reduce its usability for certain applications. The data are provided “as is” and neither NASA nor METI/ERSDAC will be responsible for any damages resulting from use of the data.

ASTER GDEM 2 is subject to user acknowledgment of redistribution and citation policies required by METI and NASA. Product tiles may be downloaded electronically from ERSDAC and from the LP DAAC by visiting:

NASA Reverb

LP DAAC Global Data Explorer

ERSDAC Ground Data System (GDS) Information Management System (IMS)

Source: https://lpdaac.usgs.gov
 
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