Quality assessment of digital surface models derived from the Shuttle Radar Topography Mission (SRTM)

In February 2000 the Shuttle Radar Topography Mission (SRTM) was flown on board the Space Shuttle Endeavour. The aim of the mission was to survey about sixty percent of the complete landmasses of the Earth's surface. During the mission a US C-band antenna and a German/Italian X-band antenna were installed on board the Shuttle. The main result of the mission will be a three-dimensional digital surface model (DSM) obtained from single-pass interferometry. During the validation process the SRTM elevation data will be analysed by comparing them to reference data of a well-known test site. This paper describes and investigates an algorithm for this task which was developed at the Institute for Photogrammetry and Engineering Surveys (IPI) of the University of Hannover. It is based on a spatial similarity transformation which matches the SRTM data onto reference data of higher accuracy. The algorithm is comparable to the absolute orientation of a photogrammetric block by means of a DTM. Any detected transformation parameters which differ from the identity transformation point to potentially existing systematic errors of the SRTM data, the standard deviation of the remaining height differences represents the accuracy of the SRTM data. The algorithms was successfully tested using simulated and real data, the obtained results are reported in this paper.