Steve Cole
Headquarters, Washington
202-358-0918
stephen.e.cole@nasa.gov
Alan Buis
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-0474
alan.buis@jpl.nasa.gov
RELEASE: 11-351
NASA, JAPAN RELEASE IMPROVED TOPOGRAPHIC MAP OF EARTH
WASHINGTON -- NASA and Japan released a significantly improved version
of the most complete digital topographic map of Earth on Monday,
produced with detailed measurements from NASA's Terra spacecraft.
The map, known as a global digital elevation model, was created from
images collected by the Japanese Advanced Spaceborne Thermal Emission
and Reflection Radiometer, or ASTER, instrument aboard Terra.
So-called stereo-pair images are produced by merging two slightly
offset two-dimensional images to create the three-dimensional effect
of depth. The first version of the map was released by NASA and
Japan's Ministry of Economy, Trade and Industry (METI) in June 2009.
"The ASTER global digital elevation model was already the most
complete, consistent global topographic map in the world," said Woody
Turner, ASTER program scientist at NASA Headquarters in Washington.
"With these enhancements, its resolution is in many respects
comparable to the U.S. data from NASA's Shuttle Radar Topography
Mission (SRTM), while covering more of the globe."
The improved version of the map adds 260,000 additional stereo-pair
images to improve coverage. It features improved spatial resolution,
increased horizontal and vertical accuracy, more realistic coverage
over water bodies and the ability to identify lakes as small as 0.6
miles (1 kilometer) in diameter. The map is available online to users
everywhere at no cost.
"This updated version of the ASTER global digital elevation model
provides civilian users with the highest-resolution global topography
data available," said Mike Abrams, ASTER science team leader at
NASA's Jet Propulsion Laboratory in Pasadena, Calif. "These data can
be used for a broad range of applications, from planning highways and
protecting lands with cultural or environmental significance, to
searching for natural resources."
The ASTER data cover 99 percent of Earth's landmass and span from 83
degrees north latitude to 83 degrees south. Each elevation
measurement point in the data is 98 feet (30 meters) apart.
NASA and METI are jointly contributing the data for the ASTER
topographic map to the Group on Earth Observations, an international
partnership headquartered at the World Meteorological Organization in
Geneva, Switzerland, for use in its Global Earth Observation System
of Systems. This "system of systems" is a collaborative,
international effort to share and integrate Earth observation data
from many different instruments and systems to help monitor and
forecast global environmental changes.
ASTER is one of five instruments launched on Terra in 1999. ASTER
acquires images from visible to thermal infrared wavelengths, with
spatial resolutions ranging from about 50 to 300 feet (15 to 90
meters). A joint science team from the United States and Japan
validates and calibrates the instrument and data products. The U.S.
science team is located at JPL.
NASA, METI, Japan's Earth Remote Sensing Data Analysis Center
(ERSDAC), and the U.S. Geological Survey validated the data, with
support from the U.S. National Geospatial-Intelligence Agency and
other collaborators. The data are distributed by NASA's Land
Processes Distributed Active Archive Center at the U.S. Geological
Survey's Earth Resources Observation and Science Center in Sioux
Falls, S.D., and by ERSDAC in Tokyo.
Users of the new version of the ASTER data products are advised that
while improved, the data still contain anomalies and artifacts that
will affect its usefulness for certain applications.
Data users can download the ASTER global digital elevation model at:
or
http://www.ersdac.or.jp/GDEM/E/4.html
For more information about NASA's Terra mission, visit:
-end-
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