DEM Generation from ERS SAR shorelines compared to airborne crosstrack InSAR DEM's in the German bight
by Edzard Romaneessen, Susanne Lehner, Andreas Niedermaier, Danielle Hoja
The intertidal area of the German Bight is continuously changing its topography
due to morphodynamic processes. This fact has serious impact on German waterways,
requiring a huge amount of dragging with costs of about 80 Mio Dm per annum.
In order to monitor morphodynamic changes and to continuously update the changes in the bottom topography shoreline information extracted from SAR (Synthetic Aperture Radar) images of the European Remote Sensing Satellite ERS 1/2 at different tidal levels are interpolated into a digital elevation model (DEM). Therefor, the shorelines are extracted with a new developed method using a combination of wavelet and active contours. The corresponding height information is interpolated from tide gauge data. In a final step, from this height information a DEM is generated using a weighted mean interpolation in space and time. For validation purpose, the extracted shorelines and the interpolated DEM's are compared to independent generated DEM's based on airborne crosstrack interferometric SAR images as well as on ground truth measurements. In total some 100 ERS SAR Szenes from 1992 til 2000 are used to identify morphodynamical active areas in the German Bight.