Updating and upgrading a global Digital Elevation Model - the fully automated production of WorldDEM Neo with acquisitions until 2025

Currently available global Digital Elevation Model (DEM) surfaces are either derived from the stereoscopic exploitation of multispectral satellite imagery, point-wise laser altimetry measurements or the interferometric processing of bistatic synthetic aperture radar data, but only radar data allows the acquisition of a global product in a reasonable timeframe. The public private partnership of DLR and Airbus in the TanDEM-X mission paved the ground for the WorldDEM product line and its derivatives such as the Copernicus DEM. Both datasets are based on data acquisitions from December 2010 to January 2015, manual and semi-automated DEM editing procedures and represent a very accurate, very consistent and only pole-to-pole DEM data set. The Copernicus DEM is available with a free-and-open licence.

Various ecosystems such as the geosphere, biosphere, cryosphere and anthroposphere are subject to continuous changes which demand the monitoring of Earth’s topography in regular updates of global Digital Elevation Model data. The WorldDEM Neo product represents the successor of the aforementioned WorldDEM but is based on a fully-automated editing & production process and newer data: the on-going TanDEM-X mission is expected to operate until 2028 and has created an archive of up-to-date DEM scenes ready for integration into a new global DEM coverage (>90% of global landmass acquired between 2017 and 2021; ~60% of global landmass acquired again between 2021 and 2025). In conjunction with continuous improvements of the fully-automated production processes, a new global DEM coverage of WorldDEM Neo is produced early 2026. DEM applications such as the orthorectification of raw satellite imagery will benefit from the availability of an accurate and up-to-date global DEM dataset. Other applications such as multi-temporal 3D change analysis based on a single satellite mission (TanDEM-X) are possible and support the understanding of environmental changes thanks to the 3rd dimension. The rapid availability of the error-compensated WorldDEM Neo Digital Surface Model (DSM) and bare-ground Digital Terrain Model (DTM) after raw data acquisition serve various applications of global DEMs. Future acquisitions of the on-going TanDEM-X mission (until 2028) allow the processing of final and up-to-date DSM and DTM coverages at the end of the mission lifetime.

The presentation comprises a short look into the history with its manual & semi-automated DEM editing procedures. The main focus will be on the fully-automated production processes for truly global DSM & DTM coverages. Accuracy metrics, 3D change statistics between the different global coverages but also visual impressions of the various global DEM coverages will be addressed, too. On-going challenges with interferometry-based elevation data are part of an outlook and different error compensation strategies (e.g. height reconstruction from radar amplitude data based on machine-learning techniques) are highlighted.