The data, comprising 1.3 million images, comes from a collaboration between the US space agency Nasa and the Japanese trade ministry.
The images were taken by Japan’s Advanced Spaceborne Thermal Emission and Reflection Radiometer (Aster) aboard the Terra satellite. The Terra satellite, dedicated to Earth monitoring missions, has shed light on issues ranging from algal blooms to volcano eruptions.
The resulting Global Digital Elevation Map covers 99% of the Earth’s surface, and is free to download and use. There are some limitations on the number of downloads that you can order as the immediate load on the servers following the launch is going to be massive but it will be more than enough for anyone looking to download a high quality terrain model of Ireland for example. Elevations have been measured at 30m centres which while not at GPS survey levels is much, much closer than it ever was.
Previously, the most complete such topographic map was Nasa’s Shuttle Radar Topography Mission, covering 80% of the Earth’s surface. However, the mission’s results were less accurate in steep terrain and in some deserts.
Nasa is now working to combine this older data with the new Aster observations to further improve on the global map.
It’ll mean much more accurate models for Flight simulation, improved “Google Earth” elevation modelling and a great deal of other stuff.
On a slightly different but related tack, the American GPS satellites are reaching the end of their lifespan and there is considerable debate regarding the current funding in place to replace them as they fail. At current funding levels the system will be useless by the early to mid 2010’s. There just won’t be enough satellites up there to give any reasonable accuracy. When we get the European “Galileo” satellite positioning system up and running, this promises to bring in-car or handheld GPS systems accurate to within 1 metre (Currently running at about 5-7 meters with GPS or the Russian GLONASS) for all areas covered under the European system. Of course that means that the current 10mm horizontal limit and 15mm vertical limits given by Kinetic GPS (Or Russian GLONASS) surveying systems when coupled with base stations will resolve to about 1-2mm with the new Galileo system. This is more than accurate enough for on site surveying and much more than is required for Ordnance Survey and general mapping work. Hopefully this will be up and running before the GPS system collapses.
What all of this new data means of course is that when Microsoft brings out the new version of Flight Simulator for me to dabble with, I’ll need something like a mini-Cray with a 20 terabyte hard drive to run the thing. I have to start saving for new parts again. Now where is that “Building your own PC for Dummies” book gone……