NASA, Japan Release Most Complete Topographic Map of Earth

PASADENA, Calif. – NASA and Japan released a new digital topographic map of Earth Monday
that covers more of our planet than ever before. The map was produced with detailed measurements
from NASA's Terra spacecraft.

The new global digital elevation model of Earth was created from nearly 1.3 million individual stereo-
pair images collected by the Japanese Advanced Spaceborne Thermal Emission and Reflection
Radiometer, or Aster, instrument aboard Terra. NASA and Japan's Ministry of Economy, Trade and
Industry, known as METI, developed the data set. It is available online to users everywhere at no
cost.

"This is the most complete, consistent global digital elevation data yet made available to the world,"
said Woody Turner, Aster program scientist at NASA Headquarters in Washington. "This unique
global set of data will serve users and researchers from a wide array of disciplines that need elevation
and terrain information."

According to Mike Abrams, Aster science team leader at NASA's Jet Propulsion Laboratory in
Pasadena, Calif., the new topographic information will be of value throughout the Earth sciences and
has many practical applications. "Aster's accurate topographic data will be used for engineering,
energy exploration, conserving natural resources, environmental management, public works design,
firefighting, recreation, geology and city planning, to name just a few areas," Abrams said.

Previously, the most complete topographic set of data publicly available was from NASA's Shuttle
Radar Topography Mission. That mission mapped 80 percent of Earth's landmass, between 60 degrees
north latitude and 57 degrees south. The new Aster data expand coverage to 99 percent, from 83
degrees north latitude and 83 degrees south. Each elevation measurement point in the new data is 30
meters (98 feet) apart.

"The Aster data fill in many of the voids in the shuttle mission's data, such as in very steep terrains
and in some deserts," said Michael Kobrick, Shuttle Radar Topography Mission project scientist at
JPL. "NASA is working to combine the Aster data with that of the Shuttle Radar Topography
Mission and other sources to produce an even better global topographic map."

NASA and METI are jointly contributing the Aster topographic data 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.

NASA, METI and the U.S. Geological Survey validated the data, with support from the U.S.
National Geospatial-Intelligence Agency and other collaborators. The data will be distributed by
NASA's Land Processes Distributed Active Archive Center at the U.S. Geological Survey's Earth
Resources Observation and Science Data Center in Sioux Falls, S.D., and by METI's Earth Remote
Sensing Data Analysis Center in Tokyo.

Aster is one of five Earth-observing instruments launched on Terra in December 1999. Aster acquires
images from the visible to the thermal infrared wavelength region, with spatial resolutions ranging
from about 15 to 90 meters (50 to 300 feet). A joint science team from the U.S. and Japan validates
and calibrates the instrument and data products. The U.S. science team is located at JPL.

For visualizations of the new Aster topographic data, visit:
http://www.nasa.gov/topics/earth/features/20090629.html .

Data users can download the Aster global digital elevation model at:
https://wist.echo.nasa.gov/~wist/api/imswelcome and http://www.gdem.aster.ersdac.or.jp .

For more information about NASA and agency programs, visit: http://www.nasa.gov .

JPL is managed for NASA by the California Institute of Technology in Pasadena.

Trying to download some now. Many hoops need to be jumped through and once you have worked out the area you need, you place an order and wait for the download link to be emailed. Hopefully it will be more accurate than the 90m stuff we use now.

Cheers,
David.

Well that didn't work Receive this error when opening the .tiff in Demex.



More digging required

I was finally able to get one of the GeoTIFFs to open in Demex by saving it as a dem with 3Dem. However, the results are not worth it and they are much worse than the 90m SRTM dem's used now. This area is just north of where I live and the 90m terrain is fairly accurate. The ground level for the marker in the distance is 2 metres higher than the camera location.



The same area with the new data.



The terrain undulates like the sand dunes of the Simpson Desert! This is all cane growing land and I can't help but wonder if height of the cane somehow affects the satellite images used to create the data. The data headers for the TIFFs lists the resolution at 27m, so it should be far more accurate than the 90m SRTM dems.

Thanks for that useful feedback David. Looks like I'll have to chug along with the 90M data for a bit longer

Hi All,
As I understand it, DEM reads the tops of buildings/trees etc. I know that in laying track in Phil's route, the terrain is at the tree tops north of Raleigh and around Pine Creek Rd where it is solid tree tops and I have had to make allowance accordingly. Readings over a city (Adelaide) are equally higher than the ground would be.
It would appear that the new high res DEM appears to amplify the problem.
In areas of SA that we model where trees are few and far between, the new DEM would be good, but in heavily wooded and/or city areas, be aware of the potential problem.
Cheers
Allan

Sarfan39 is correct here. The DEM data was collected on Space shuttle mission STS 99 Launched on 11 Feb 2000. It carried a C band imaging radar modified for use in the space shuttle. The Wave length of C band means it will reflect off anything longer than about 4 to 8 cms. I have definitely proved it will show up trees. The way it effects the data is that a single data element of the DEM represents the AVERAGE height of every thing in its area.(In victoria this is aprox 93 metres by 78 metres) If the area is covered in trees by say 33% and they are an average height of 9 metres the height of the element will be 3 metres higher than It should be.

Some time back I did an evaluation of the 3DEM data and in areas such as around Mt Slide North of Healsville the data indicated a height of 40 to 45 metres above the terrain, that is roughly the height of the trees.
Just south east of Benalla is the reef hills forest the data here indicated a height of between 6.5 to 9 metres above the terrain this proved to be close to the height of the leaf canopy in the forest.

It is also interesting to note that some roads show up in the data because of the lines of trees in the road reserve, small streams show up for the same reason.

Checks though showed that the accuracy of the DEM data is excellent positional accuracy was at least within 20 metres, ie a 1/4 of the pitch of the elements and heights in areas mostly clear of large vegitation was within 1 to 2 metres. This is significantly better than the specs in the SRTM documentaion.........

NASA has gone to much trouble to get the 3DEM data accurate, I am going to check on the accuracy and characteristics of this new source some time soon.