QUALITY ASSESSMENT FOR THE FIRST PART OF THE TANDEM-X GLOBAL DIGITAL ELEVATION MODEL

Abstract. TanDEM-X is an innovative synthetic aperture radar (SAR) mission with the main goal to generate a global and homogeneous digital elevation model (DEM) of the Earth’s land masses. The final DEM product will reach a new dimension of detail with respect to resolution and quality. The absolute horizontal and vertical accuracy shall each be less than 10 m in a 90% confidence interval at a pixel spacing of 12 m. The relative vertical accuracy specification for the TanDEM-X mission foresees a 90% point-to-point error of 2 m (4 m) for areas with predominant terrain slopes smaller than 20% (greater than 20%) within a 1° longitude by 1° latitude cell. The global DEM is derived from interferometric SAR acquisitions performed by two radar satellites flying in close orbit formation. Interferometric performance parameters like the coherence between the two radar images have been monitored and evaluated throughout the mission. In a further step, over 500,000 single SAR scenes are interferometrically processed, calibrated, and mosaicked into a global DEM product which will be completely available in the second half of 2016. This paper presents an up-todate quality status of the single interferometric acquisitions as well as of 50% of the final DEM. The overall DEM quality of these first products promises accuracies well within the specification, especially in terms of absolute height accuracy.