Global 12m DEM with TanDEM-X satellite
Tuesday, June 22, 2010 at 8:52PM 
Comparison between SRTM and TanDEM-XFrom the BBC: The TanDEM-X satellite has blasted into orbit on a mission to acquire the most precise 3D map of the Earth's surface.
The German radar spacecraft will fly in formation with an identical platform called TerraSAR-X launched in 2007. Together, the pair will measure the variation in height across the globe to an accuracy of better than two metres.
With the TanDEM mission, the intention is to go down to a vertical resolution of two metres, with a spatial resolution of 12m by 12m. Airborne laser instruments (lidars) can do better than this but their DEMs are only regional. To achieve the TanDEM level of detail on all 150 million sq km of the Earth's land surface will require three years of operation.
Reader Comments (1)
Nice video of the system here.
Also they say: At times, the two satellites will be separated by as little as 200m. The compact orbital dance will give the pair "stereo vision", by enabling them to operate an interferometric mode in which one spacecraft acts as a transmitter/receiver and the other as a second receiver. Three-dimensional image acquisition is expected to start in earnest in January.