In: Wagner W,, Szekely, B. (eds.): ISPRS TC VII Symposium - 100 Years ISPRS, Vienna, Austria, July 5-7, 2010, IAPRS, Vol. XXXVIII, Part 7B 
PERSISTENT SCATTERER INTERFEROMETRY BASED ON 
TERRASAR-X IMAGERY: THE BARCELONA TEST AREA 
M. Crosetto 3 ’*, O. Monserrat 3 , M. Cuevas 3 , B. Crippa b 
a Institute of Geomatics, Av. del Canal Olimpic, s/n, Castelldefels, E-08860, Spain 
michele.crosetto@ideg.es, oriol.monserrat@ideg.es, maria.cuevas@ideg.es 
b Department of Earth Sciences, University of Milan, Via Cicognara 7, 20129 Milan, Italy - bruno.crippa@unimi.it 
Commission VII, WG VII/2 
KEY WORDS: Remote Sensing, Satellite, Detection, Deformation, Geocoding. 
ABSTRACT: 
The aim of this paper is deformation monitoring over urban areas using Persistent Scatterer Interferometry (PSI) and Very High 
Resolution (VHR) X-band SAR imagery. Since the launch of TerraSAR-X and the first COSMO-SkyMed satellite (both were 
launched in June 2007), the VHR X-band data has grown in importance as source of PSI. This is due to the remarkable increase of 
the data acquisition capability (for instance, the COSMO-SkyMed constellation consists of three SAR satellites in mid 2010), the 
progressive loss of key sources of SAR images, as ASAR-Envisat and ERS-2, and the promising technical characteristics of the X- 
band. This paper illustrates some of the main results of the PSI analysis derived from VHR X-band data. The analysis was carried 
out over a stack of SAR images captured by the TerraS AR-X sensor and covering the metropolitan area of Barcelona (Spain). This 
work is the first experience of the authors with PSI analysis of the X-band, which is based on a rich set of 28 StripMap images. 
These images were processed and analysed using the PSI in-house experimental software chain of the Institute of Geomatics. A 
description of the Barcelona dataset and the main outcomes of the PSI analysis is given. These outcomes reflect a preliminary 
assessment of the improvement which can be achieved by VHR X-band PSI, mainly in terms of deformation monitoring capability. 
1. INTRODUCTION 
This paper describes a technique for deformation monitoring 
over urban areas based on Persistent Scatterer Interferometry 
(PSI) and very high resolution (VHR) X-band Synthetic 
Aperture Radar (SAR) images, captured by the TerraS AR-X 
sensor. In particular, it summarizes the experience of the 
authors in the analysis of a test area: the metropolitan area of 
Barcelona (Spain). 
PSI is a radar-based remote-sensing technique to measure and 
monitor land deformation (see Rosen et al., 2000; Crosetto et 
al., 2005). PSI represents the most advanced category of 
DInSAR techniques. Different PSI approaches have been 
proposed in the last decade (see Ferretti et ah, 2001; Berardino 
et ah, 2002; Colesanti et ah, 2003; Mora et ah, 2003; Lanari et 
ah, 2004; Hooper et ah, 2004; Kampes and Hanssen, 2004; 
Crosetto et ah, 2005; Pepe et ah, 2005; Crosetto et ah, 2008). 
The availability of SAR data acquired by space-borne sensors 
represents a key issue for the successful use of PSI. In 
particular, image acquisition continuity over large periods of 
time plays a fundamental role in PSI. Note that the data must be 
acquired by the same sensor or compatible sensors, as in the 
case of ERS-1 and ERS-2. The first satellite that allowed 
demonstrating the potentialities of the PS technique was ERS-1. 
This satellite has been operative for 10 years and, more 
importantly, together with its almost exact replica ERS-2, has 
provided a valuable historical archive of interferometric SAR 
data. ERS satellites have provided global spatial coverage over 
a time period of 19 years, with the first images dating back to 
summer 1991. There are hundreds of high level scientific 
* Corresponding author. 
publications that demonstrate the success of the ERS mission. 
Radarsat-1 and ASAR-Envisat have also been particularly 
important PSI data sources. The latest Differential 
Interferometric SAR (DInSAR) results based on data acquired 
by the ERS and Envisat satellites can be found at 
http://eopi.esa.int/ 
A new generation of sensors has been launched in the last few 
years, including the C-band Radarsat-2 (launched in December 
2007 by the Canadian Space Agency), the X-band TerraSAR-X 
(launched in June 2007 by a joint venture carried out under a 
public-private-partnership between the German Aerospace 
Centre, DLR, and EADS Astrium GmbH; the exclusive 
commercial exploitation rights are held by Infoterra GmbH), 
and the X-band COSMO-SkyMed (Constellation of small 
Satellites for the Mediterranean basin Observation, conducted 
by the Italian Space Agency, ASI; the current constellation 
includes three satellites). 
The last two systems, TerraSAR-X and COSMO-SkyMed are 
particularly promising due to their very high spatial resolution 
imaging capabilities and the use of the X-band. One of the key 
tasks of the PSI research teams spread all over the world is to 
study the performance of these two very promising types of 
SAR data. The goal of this paper is to describe the first 
experience of the authors in the PSI analysis based on a rich set 
of TerraSAR-X images. These images were processed using the 
PSI in-house experimental software chain of the Institute of 
Geomatics. This paper describes a dataset covering the 
metropolitan area of Barcelona and the main outcomes of the 
preliminary PSI analysis. 
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