Nouvelles données ASTER

Un nouveau MNT Global de la NASA

Sources : lhttp://www.ersdac.or.jp/GDEM/E/4.html

The ASTER Global Digital Elevation Model (ASTER GDEM) is a joint product developed and made available to the public by the Ministry of Economy, Trade, and Industry (METI) of Japan and the United States National Aeronautics and Space Administration (NASA).  It is generated from data collected from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), a spaceborne earth observing optical instrument.

The ASTER GDEM is the only DEM that covers the entire land surface of the Earth at high resolution.  Since the release of the Version 1 on June 29, 2009 (*1), the ASTER GDEM has been widely used by many users (*2) and it has greatly contributed to the global earth observing community.

(*1) METI press release (June 26, 2009)
http://www.meti.go.jp/english/press/data/20090626_03.html
(*2) About 5.86 million tiles (1 tile: 1 x 1 degree latitude and longitude) downloaded as of the end of August 2011

Version 2 of the ASTER GDEM is developed, employing an advanced algorithm to improve GDEM resolution and elevation accuracy and reprocessing a total of 1.5 million scene data including additional 250,000 scenes acquired after the previous release.  Accuracy of this latest version is validated by the collaborate effort between Japan and the United States, which shows significant improvements over Version 1 (*3).  The ASTER GDEM Version 2 will be formally released as an upgrade to Version 1 on October 17, 2011.

(*3) Link to “Quality Improvements in Version 2”

 

Pour la précision des données :

(Example 1) Enhanced ground resolution: The Northern Alps, Japan
The resolution was greatly improved by the new GDEM generation algorithm, from equivalent to about 120m (Version 1) to 70 m (Version 2).

Ver.2	Ver.1
Enhanced ground resolution

(Example 2) Reduction of voids: High-latitude areas
Voids observed at high latitudes in Version 1 are removed significantly in Version 2 after addition of 350,000 new scenes

Ver.2	Ver.1
Reduction of voids (black indicates data void)

(Example 3) Flat lake surface: Lake Nicaragua
Lake surface appears completely flat in Version 2 by the new GDEM generation algorithm.

Ver.2	Ver.1
Flat lake surface

(Example 4) Correction of anomalies: Northeastern part of southern Africa
Anomalies caused due to lack of observation data disappeared after addition of 350,000 new scenes.

Ver.2	Ver.1
Corrected step anomalies