MULTI-SCALE MT-INSAR TECHNIQUES FOR STRUCTURAL HEALTH MONITORING: APPLICATIONS TO THE ITALIAN CULTURAL HERITAGE CONTEXT

Abstract

In recent years, the number of applications of Multi-Temporal Interferometric Synthetic Aperture Radar (MT-InSAR) techniques for structural health monitoring (SHM) purposes has constantly raised. One of the main advantages that MT-InSAR can provide is the possibility to analyze wide areas, such as entire cities or archaeological sites. Thus, several interferometric algorithms have proven to be particularly valid when applied in urban contexts, considering the high reflectivity provided by the structures. In addition, the growing availability of high-resolution SAR satellite constellations, such as the Italian COSMO-SkyMed and the German TerraSAR-X, allows obtaining significantly accurate measures and detecting high density of Measurement Points (MP). Consequently, sufficiently detailed information on single structures can be recorded, permitting to perform both urban scale and local scale analyses. On the other hand, several drawbacks are still present, mostly related to the hardly post-processing processes needed. Indeed, beside the technical difficulties that can be encountered during the analysis (e.g. geocoding errors and noisiness in the time series), an expert interpretation of the results is still required to avoid misinterpretation of data. Anyway, considering both advantages and disadvantages of the technique, MT-InSAR undoubtedly represents a very cost-effective tool in the structural monitoring field. In this paper, MT-InSAR applications for structural monitoring on the Italian Cultural Heritage context are presented. The analyses have been conducted at both urban and local scale, processing images acquired by COSMO-SkyMed constellation in Stripmap mode (~3 meters resolution). First, spatial interpolation algorithms have been implemented to estimate the overall deformations at urban scale. Subsequently, the attention has focused on some of the main cultural assets of the case-study cities, investigating the MPs detected on the structures themselves. In this work, three cities are presented as case-studies: Verona, Padova (North Italy), and L’Aquila (central Italy). For each city, a specific Cultural Heritage structure has been selected for the local scale analysis, namely the Roman Arena in Verona, the Scrovegni Chapel in Padova, and the Civic Tower in L’Aquila. All these monuments have been monitored by traditional SHM techniques for years, with the possibility to correlate and validate onsite and satellite data.