DUDES

The objective of the DUDES project was to produce a Digital Elevation Model (DEM) over a large European area (minimum 300,000 km2) using the X-SAR data from the Shuttle Radar Topography Mission (SRTM) and the SAR tandem data from the ESA ERS missions (ERS-1 and ERS-2). The area covered three countries from the ESA Member States.

DUDES aimed at demonstrating the possibility to produce high quality spaceborne derived DEMs over large areas.

The Shuttle Radar Topography Mission (SRTM) was a joint project between the US National Imagery and Mapping Agency (NIMA), the US National Aeronautics and Space Administration (NASA), the Italian Space Agency (ASI) and the German Space Agency (DLR). The objective of the SRTM mission was to produce digital topographic data for 80 percent of the Earth's land surface (all land areas between 60 degree north and 56 degree south latitude), with data points located every 1-arc second (approximately 30 meters) on a latitude/longitude grid.

Two independent radar systems were operated simultaneously during the SRTM mission: the German X-SAR instrument (3.1 cm wave length) and the American SIR-C instrument (5.6 cm wave length). The C-band radar scanned the earth's surface with a 225 kilometer-wide swath and was able to completely map the covered area, the X-band swath - located within the C-band swath - was only 50 km-wide.

The ERS satellites were acquiring between 1995 and 2000 data in tandem mode, where ERS-2 was followed by ERS-1 with a 1-day repeat orbit interval. During that period Europe was covered many times by ERS tandem data. The tandem mode operations boosted the development of interferometric applications and led to the development of operational tools for interferometric processing and DEM generation all over the world.