Flying in formation, TanDEM-X and TerraSAR-X will generate a precise global elevation model.
For vast swathes of Earth, at present only rough, inconsistent, or incomplete elevation models are available from different data sources and measurement techniques. TanDEM-X will close these gaps and will provide precise elevation data in a 12-metre grid. This elevation model shows different accuracies: 1 kilometre, 90 metres, 30 metres and 12 metres (TanDEM-X).
Source:The Earth in 3D - German radar satellite TanDEM-X launched successfully