Potential and limits of non-local means InSAR filtering for TanDEM-X high-resolution DEM generation

The primary objective of the German TanDEM-X mission is the generation of a globally available, highly accurate and detailed digital elevation model (DEM), with the final product having 12 m posting, 2 m relative and 10 m absolute vertical accuracy. The first version of this global DEM has been finalized by the German Aerospace Center (DLR), in September 2016. Our experience with the experimental application of non-local means filters to TanDEM-X data suggests that TanDEM-X has the potential of producing DEMs of even higher resolution and accuracy. The goal of this investigation is to explore the possibility of employing non-local InSAR filters to achieve an effective resolution of 6 m, with an equivalent posting, and a relative height error below 0.8 m, i.e. an increase of quality by a factor of 2 × 2 in resolution and a factor of 2 m/0.8 m = 2.5 in height accuracy — all in all one order of magnitude.