Luzi, Guido

In this paper, we propose a combined use of real aperture radar (RAR) and synthetic aperture radar (SAR) sensors, within an interferometric processingchain, to provide a new methodology for monitoring urban environment and historical buildings at different temporal and spatial scales. In particular, ground-based RAR measurements are performed to estimate the vibration displacements and the natural oscillation frequencies of structures, with the aim of supporting the understanding of the building dynamic response. These measurements are then juxtaposed with ground-based and space-borne SAR data to monitor surface deformation phenomena, and hence, point out potential risks within an urban environment. In this framework, differential interferometric SAR algorithms are implemented to generate short-term (monthly) surface displacement and long-term (annual) mean surface displacement velocity maps at local (hundreds m2) and regional (tens km2) scale, respectively. The proposed methodology, developed among the activities carried out within the national project Programma Operativo Nazionale MASSIMO (Monitoraggio in Area Sismica di SIstemi MOnumentali), is tested and discussed for the ancient structure of Saint Augustine compound, located in the historical center of Cosenza (Italy) and representing a typical example of the Italian Cultural Heritage.

The risk and the vulnerability mitigation of historical heritages (e.g. churches, museums and monuments) is an actual relevant topic of interest for their safeguarding with respect to environmental risks, for example considering the high seismic hazard level of their surrounding areas. Based on this rationale, in this paper, classical Non Destructive Testing (NDT) techniques and proximal remotely sensed tools (i.e..a terrestrial laser scanner, an infrared thermal camera and an interferometric real aperture radar) are jointly used for both structural health monitoring and materials control analysis of historical heritages. The proposed approach aims at providing synthetic parameters useful to evaluate the static and dynamic properties of selected structures, such as the 3-dimensional (3D) model reconstruction of the building with the detailed analysis of its structural elements, the thermographic analysis of surface anomalies related to climate induced phenomena, and the vibrating modes of some relevant elements due to environmental induced stresses. Some meaningful results obtained for selected structures within Calabria Region allow showing the benefits of the proposed approach for the non-invasive and non-destructive heritages monitoring in a seismic area.

The mitigation of seismic vulnerability related to both cultural and historical buildings is a very important issue especially when considering monumental heritages located on seismic areas, since it allows defining the seismic risk of selected structures. Within such a framework, Non Destructive Testing (NDT) techniques and proximal remotely sensed tools play a key role for providing the damage detection and the conservation status evaluation of heritages, especially in response to seismic hazards. Based on this rationale, the proposed study aims at providing a methodology relevant to the integrated use of Terrestrial Laser Scanner (TLS), Infrared Thermal Camera (IR-TC) and Real Aperture Radar (RAR) sensors for both the structural health monitoring and the seismic risk mitigation of monumental heritages. Some preliminary results, gathered for the Brettii & Enotri Museum in Cosenza and the San Nicola Church in Briatico, are properly described to show the benefits of both the proposed approach and the powerful capabilities of proximal remote sensing tools to support classical measurement techniques for the monumental heritages monitoring in a seismic area. Furthermore, some future perspectives are summarized in order to integrate and improve the results of the structural analyses.

Sommario In questo lavoro viene presentata una metodologia di indagine NDT (acronimo inglese di Non Destructing Testing), basata su tecniche classiche di misura, telerilevamento prossimale e satellitare ad alta risoluzione spaziale, analisi sismogenetiche ed indagini geofisiche, per la mitigazione del rischio sismico di edifici storici monumentali soggetti a tutela. I risultati sperimentali, ottenuti per il caso di studio del complesso monumentale di Sant’Agostino ubicato nella città di Cosenza, dimostrano l’efficacia dell’approccio proposto sia per applicazioni correnti (il monitoraggio materiale e strutturale di un manufatto), sia per applicazioni emergenti (mitigazione del rischio sismico di beni storici).

The monitoring of Cultural Heritages conservation is an operational issue that requires a multidisciplinary approach able both to provide the dynamic and sustainable cultural heritage surveying and improve the understanding of historical materials in response to pollutants or climate changes, as well as natural events (e.g. earthquakes, avalanches and flooding hazards) [1]. Within such a framework, different methodologies are proposed in literature for Cultural Heritage monitoring, such as topographical surveys, digital photogrammetry, laser scanning, Global Positioning System (GPS), optical/radar satellite remote sensing, multispectral image analysis, 3-Dimensional (3D) modeling, Geographic Information System (GIS) [2]. The peculiarities of each case study and the difficult working conditions require particular solutions in terms of costs, acquisition time and generated products, which can be addressed and solved by considering a multi-technique surveying approach. In this study, an integrated system of proximal remotely-sensed tools is proposed and investigated for Cultural Heritage surveying, which consists of a Ground-Based Synthetic Aperture Radar (GBSAR), a GB Real Aperture Radar (RAR) and a Terrestrial Laser Scanner (TLS). Preliminary results are presented for the Sant’Agostino Church in Cosenza to show the benefits of the proposed approach for Cultural Heritages monitoring.