Urban DEM

Daniele Perissin(1) and Fabio Rocca(1)

(1) Politecnico di Milano, Piazza L. da Vinci 32, 20133 Milano, Italy

Abstract

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 and demonstrate 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 dependent pixels and side lobes) is addressed and an easy and efficient solution is proposed. The results obtained in the Milan site 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 submeter accuracy, and upper-level targets, where present, reveal the buildings profile. The estimated city street level (ranging ±2m in 16x18Km) is then compared with those obtained with the same technique using descending parallel track and an ascending track. Furthermore, new insights to the PS physical nature have been discovered by using different polarizations, that show the prevalence of dihedrals on the ground and single-bounce scatterers at higher elevations. Then a cross-check of the PS elevation has been carried out by analysing the temperature-dependent elongations of high structures. Finally the results of the comparison between a LIDAR DEM and the corresponding one got with the PS technique are reported.

 

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