A simple solution to mitigate noise effects in time-redundant sequences of small baseline multi-look DInSAR interferograms

We present a simple and effective filtering algorithm to mitigate noise effects in a time-redundant sequence of multi-look small baseline (SB) differential synthetic aperture radar (SAR) interferograms by exploiting the temporal relationships among the selected interferometric data pairs. The proposed method relies on the estimation of the (wrapped) filtered phase terms associated to each SAR acquisition; this result is achieved via a non-linear minimization procedure which is applied to the phase signal of conventional multi-look interferograms without any pixel selection process, and with no a-priori information on the statistics of the involved complex-valued SAR images. Following their estimation, the phase images are paired to reconstruct a new sequence of filtered SB differential interferograms, which are used to generate surface deformation products, such as deformation velocity maps and displacement time-series. The filtering algorithm effectiveness is demonstrated by analysing a set of SAR images..

Automatic generation of co-seismic displacement maps by using Sentinel-1 interferometric SAR data

Abstract We present a tool for the automatic generation of co-seismic Differential Synthetic Aperture Radar Interferometry (DInSAR) products by using space-borne SAR data. In particular, the implemented tool relies on the large availability of Sentinel-1 SAR data and on-line earthquake catalogues (e.g. USGS, INGV) to generate co-seismic Line Of Sight (LOS) interferograms and displacement maps. The processing is triggered by the occurrence of a main seismic event, according to the accessible earthquake catalogues. The tool automatically retrieves all the needed SAR acquisitions that cover a defined area across the epicentre and generates the DInSAR products that will be then openly available through the European Plate Observing System (EPOS) portal. Moreover, the possibility to implement the presented tool into the upcoming Copernicus Data and Information Access Services (DIAS) will significantly reduce the product processing time, thus implying a faster product generation and delivery. Accordingly, such a tool not only will contribute to expand the use of DInSAR products in the geoscience field, but also will play a key role on the support of the Civil Protection authorities during the management of seismic crisis

Long-term ERS/ENVISAT deformation time-series generation at full spatial resolution via the extended SBAS technique

We extend the small baseline subset (SBAS) differential synthetic aperture radar (SAR) interferometry (DInSAR) approach to allow the generation of deformation time-series by processing, at the full spatial resolution scale, long sequences of European Remote Sensing (ERS-1 and ERS-2) and Environmental Satellite (ENVISAT) SAR data acquired with the same illumination geometry. In particular, we avoid the generation of ERS/ENVISAT cross-interferograms, which are severely affected by noise phenomena due to the carrier frequency separation of the two SAR systems, and we focus on single-platform interferograms only (i.e. ERS/ERS and ENVISAT/ENVISAT interferograms) that are properly combined by applying the singular value decomposition (SVD)-based SBAS approach. Moreover, we exploit the Doppler centroid variations of the post-2000 acquisitions of the ERS-2 sensor and the carrier frequency difference between the ERS-1/2 and the ENVISAT systems, in order to maximize the number of investigated SAR pixels and to improve their geocoding. The presented results, achieved on two data sets relevant to the Napoli Bay area and to the Murge region, both located in southern Italy, confirm the effectiveness of the extended SBAS technique and demonstrate the relevance of deformation analysis carried out at the scale of single buildings or human-made structures with more than 15 years of ERS and ENVISAT acquisitions. © 2012 Taylor & Francis

MONITORAGGIO DI UNA DIGA DI TERRA CON LA TECNICA RADAR SATELLITARE

La nota illustra la tecnica satellitare di Interferometria Differenziale Radar ad Apertura Sintetica (DInSAR) per il monitoraggio dei cedimenti della diga Genzano di Lucania. La diga, costruita nel periodo 1981-1991, è tuttora soggetta a deformazioni verticali per la consolidazione di uno strato coesivo di elevato spessore (circa 300 m) sul quale è impostata. Per analizzare il fenomeno è stata esaminata la caratterizzazione geologico e geotecnica del terreno di fondazione, effettuata in fase di progetto e durante la costruzione, elaborando un modello numerico della diga e dei terreni di fondazione con il codice di calcolo FLAC2D. Il confronto delle misure satellitari con quelle tradizionali (assestimetriche e di livellazione geometrica) confermano l’attendibilità della tecnica SAR

Advanced DInSAR analysis for building damage assessment in large urban areas: an application to the city of Roma, Italy

Remote sensing data play an important role for the environmental monitoring because they allow to provide systematic information on very large areas and for a long period of time. Such information must be analyzed, validated and incorporated into proper modeling tools in order to become useful for performing risk assessment analysis. These approaches has been already applied in the field of natural hazard evaluation (i.e. for monitoring seismic, volcanic areas and landslides). However, not enough attention has been devoted to the development of validated methods for implementing quantitative analysis on civil structures. This work is dedicated to the comprehensive utilization of ERS/ENVISAT data store ESA SAR used to detect deformation trends and perform back-analysis of the investigated structures useful to calibrate the damage assessment models. After this preliminary analysis, SAR data of the new satellite mission (ie Cosmo SkyMed) were adopted to monitor the evolution of existent surface deformation processes and to detect new occurrence. The specific objective was to set up a data processing and data analysis chain tailored on a service that sustains the safe maintenance of the built-up environment, including critical construction such as public (schools, hospital, etc), strategic (dam, highways, etc) and also the cultural heritage sites. The analysis of the test area, in the southeastern sector of Roma, has provided three different levels and sub-levels of products from metropolitan area scale (territorial analysis), settlement scale (aggregated analysis) to single structure scale (damage degree associated to the structure)

An application of the SBAS-DInSAR technique for the assessment of structural damage in the city of Rome

The remote sensing technique known as Differential Synthetic Aperture Radar (SAR) Interferometry (DInSAR) allows the detection and monitoring of ground settlements, by generating deformation velocity maps and displacement time-series having centimeter to millimeter accuracy. These measurements can contribute to the evaluation of the structural conditions of the constructions. Given the settlements, different approaches exist for the assessment of the structural damage, ranging from empirical estimates to detailed finite element calculations. In this work, we integrate the results of a DInSAR analysis with an intermediate semi-empirical model to investigate three buildings located in the southern part of the city of Rome. The model, originally proposed by Finno et al. [(2005). ASCE Journal of Geotechnical and Geoenvironmental Engineering, 131(10), 1199–1210], considers each building as an equivalent laminated beam, where the layers represent the floors and the core material reproduces the infill walls. The results obtained by the model have been compared to the damages observed on the buildings, showing a good agreement and demonstrating that the proposed approach represents an effective and, at the same time, simple assessment tool for rapidly evaluating the conditions of several structures

An advanced approach to the long term SHM of structures and transport infrastructures

This work shows the preliminary monitoring results by applying in situ and remote sensing systems to a school building located in Ariccia (Rome), within the WP6 “Structural Health Monitoring and Satellite Data” 2019–21 Reluis Project. In particular, the use of the remote sensing Differential Interferometry Synthetic Aperture Radar (DInSAR) has provided a spatial map of the displacement of the investigated structure and the corresponding time-series with the aim of monitoring deformation phenomena, focusing on the local scale analysis,which produces suitable results for urban monitoring and damage assessment. The DInSAR results have been integrated with the identification of the dynamic characteristics of the structure. In-situ data was provided by the Seismic Observatory of Structures (OSS), a network of permanent seismic monitoring systems managed by the Italian Department of Civil Protection (DPC). Modal parameters were identified from the accelerometric responses recorded at several floors of the buildings. The integrated use of the two techniques has allowed to confirm the healthiness of the investigated structure, even in presence of several seismic events occurred in the area during the monitoring period. This case represents a good example about how the integration of in-situ sensors with remotely sensed data is a key factor for a sustainable structural and infrastructural monitoring and can support the planning of both maintenance and safety management