Urban Dem

The Permanent Scatterers (PS) technique is a powerful operational tool that exploits long series of SAR data for monitoring ground deformations with millimetre accuracy on a high spatial density grid of point-wise targets. The technique has been applied successfully to a number of applications from subsidence and volcano monitoring to slow-landslide detection. Aim of this work is to analyse the location capability of the PS technique, applied to the generation of urban elevation maps. The problem of the univocal identification of the PS position (discarding side lobes) is addressed and an easy and efficient solution is proposed. The results obtained in the Milan site (from ERS and Envisat data coherently combined) allow to appreciate the very high quality of an urban DEM retrieved with the PS technique. The ground level of the city is identified with sub-meter precision, and upper-level targets, where present, reveal the buildings profile. The estimated city street level (ranging ±3m in 16x18km) is then compared with those obtained with the same technique using a descending parallel track and an ascending track.