Papers by Michele Manunta
Differential Synthetic Aperture Radar Interferometry is a technique that, by making the phase dif... more Differential Synthetic Aperture Radar Interferometry is a technique that, by making the phase difference of SAR image pairs, allows to extract the information relevant to the earth surface displacements. The result of the phase difference, referred to as Interferometric Phase or Interferogram, contains different terms: the deformation phase term, a topographic phase contribution, an atmospheric phase term and the noise contibution.
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The paper discusses, using geotechnical criteria, the potentialities offered by the Small BAselin... more The paper discusses, using geotechnical criteria, the potentialities offered by the Small BAseline Subset (SBAS) Differential Synthetic Aperture Radar Interferometry (DInSAR) technique to investigate a subsidence phenomenon affecting the urban area of Sarno town (Campania Region, Italy). To this aim, low-and full-resolution data, acquired by ERS-1/2 and Envisat satellites in the period from 1992 to 2004, have been used. In particular, low-resolution DInSAR data, once validated via a comparison with ground levelling data, are analyzed in order to detect the most subsidence-affected areas where damages to buildings were recorded during past surveys. Interesting correlation between the ground deformation gradient vectors and some damage characteristics, such as the direction of building rotation axes, are shown. Then, a preliminary analysis at "building scale" by means of full-resolution DInSAR data is presented in order to study the response of some buildings to ground movements, also deriving the maximum values attained by some relevant parameters to be used in damage criteria. Finally, the usefulness of low-and full-resolution analyses for monitoring of urbanized areas is highlighted by stressing the role that the geotechnical approach can play in DInSAR data validation process as well as in pointing out all the issues to improve the reliability of the obtained results in at "building scale" studies.
This paper presents a differential synthetic aperture radar (SAR) interferometry (DIFSAR) approac... more This paper presents a differential synthetic aperture radar (SAR) interferometry (DIFSAR) approach for investigating deformation phenomena on full-resolution DIFSAR interferograms. In particular, our algorithm extends the capability of the small-baseline subset (SBAS) technique that relies on small-baseline DIFSAR interferograms only and is mainly focused on investigating large-scale deformations with spatial resolutions of about 100 100 m. The proposed technique is implemented by using two different sets of data generated at low (multilook data) and full (single-look data) spatial resolution, respectively. The former is used to identify and estimate, via the conventional SBAS technique, large spatial scale deformation patterns, topographic errors in the available digital elevation model, and possible atmospheric phase artifacts; the latter allows us to detect, on the full-resolution residual phase components, structures highly coherent over time (buildings, rocks, lava, structures, etc.), as well as their height and displacements. In particular, the estimation of the temporal evolution of these local deformations is easily implemented by applying the singular value decomposition technique.
Engineering Geology for Society and Territory - Volume 5, 2014
IEEE Transactions on Geoscience and Remote Sensing, 2011
We present an efficient space-time phase unwrap- ping (PhU) algorithm that allows us to process s... more We present an efficient space-time phase unwrap- ping (PhU) algorithm that allows us to process sequences of multitemporal full resolution differential synthetic aperture radar (SAR) interferograms for the generation of deformation time-series. The core of the proposed technique, dealing with sparse data grids, is represented by the extended minimum cost flow (MCF) (EMCF) PhU algorithm that was originally developed for
Structure and Infrastructure Engineering, 2013
ABSTRACT The remote sensing technique known as Differential Synthetic Aperture Radar (SAR) Interf... more ABSTRACT 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.
Pure and Applied Geophysics, 2009
Ground deformation affecting the Umbria region (central Italy) in the 9-year period from 1992 to ... more Ground deformation affecting the Umbria region (central Italy) in the 9-year period from 1992 to 2000 was investigated through multi-temporal Differential Synthetic Aperture Radar Interferometry (DInSAR). For the purpose, the Small BAseline Subset (SBAS) technique was adopted, which allows studying the temporal evolution of the detected deformation at two spatial scales: a low-resolution (regional) scale, and a fullresolution (local) scale. For the analysis, SAR data acquired by the European Remote Sensing (ERS-1/2) satellites along ascending and descending orbits were used. The detected deformation was analysed to investigate its relevance to geophysical, geomorphologic, and human-induced processes that may result in hazardous conditions to the population of Umbria. Low-resolution deformation data were used to: (i) determine the amount of displacement caused by the Umbria-Marche earthquake sequence from September 1997 to April 1998 in the Foligno area, (ii) determine the number and percentage of the known landslides that can be monitored by the DInSAR technology in the investigated area, and (iii) identify and measure subsidence induced by exploitation of a confined aquifer in the Valle Umbra. Results indicate that earthquakes moved through the Foligno area westwards up to 3.9 cm and with an uplift reaching 1.7 cm. Intersection in a GIS of the lowresolution deformation maps with a detailed landslide inventory map allowed the determination that the portion of landslides that can be monitored by the SBAS-DInSAR technique in Umbria ranges from 2.7% to 3.4%, and the percentage of the total landslide area ranges from 10.4% to 12.8%. In the Valle Umbra, a dependency was found between the time and the amount of detected ground deformation, and the record of water withdrawal. The full-resolution deformation data were used to investigate the movement of the Ivancich landslide, in the Assisi Municipality. Joint analysis of the spatial and the temporal characteristics of the ground displacement allowed the formulation of a hypothesis on the landslide geometry and deformation pattern.
IEEE Transactions on Geoscience and Remote Sensing, 2006
Accurate subpixel registration of synthetic aperture radar (SAR) images is an issue that is again... more Accurate subpixel registration of synthetic aperture radar (SAR) images is an issue that is again growing interest since its initial developments related to two-pass interferometry. Recent progress in coherent (multichannel) SAR processing raises the need for accurate registration of data takes acquired with large baseline spans, high temporal coverage, and with different frequency and/or operational modes. In this paper, we
International Journal of Remote Sensing, 2012
IEEE Transactions on Geoscience and Remote Sensing, 2000
We present an efficient space-time phase unwrapping (PhU) algorithm that allows us to process seq... more We present an efficient space-time phase unwrapping (PhU) algorithm that allows us to process sequences of multitemporal full resolution differential synthetic aperture radar (SAR) interferograms for the generation of deformation time-series. The core of the proposed technique, dealing with sparse data grids, is represented by the extended minimum cost flow (MCF) (EMCF) PhU algorithm that was originally developed for the analysis of sequences of multilook interferograms. In particular, our method relies on the joint analysis of the spatial and temporal relationships among a set of properly selected multitemporal differential interferograms, which are compatible with the Small BAseline subset (SBAS) deformation time-series technique.
IEEE Transactions on Geoscience and Remote Sensing, 2000
We investigate the capability improvement of the advanced differential interferometric synthetic ... more We investigate the capability improvement of the advanced differential interferometric synthetic aperture radar (DInSAR) techniques to map deformation phenomena affecting urban areas by exploiting multitemporal SAR data acquired by the new X-band sensors with respect to those of the previous C-band systems. In particular, we perform a comparative analysis of the deformation time-series retrieved by applying the full-resolution Small BAseline Subset DInSAR technique to selected sequences of SAR data acquired by the ENVISAT and RADARSAT-1 sensors (both operating at C-band) and by the X-band radar systems onboard the SAR sensors of the COSMO-SkyMed (CSK) constellation. This study, focused on the city of Napoli (Italy), allows us to quantify the dramatic increase of the DInSAR coherent pixel density achieved by exploiting the high-resolution X-band CSK SAR images (a few meters), resulting in an improvement factor of about 320% and 550%, with respect to the RADARSAT-1 and ENVISAT products, respectively. This improvement permits us to analyze nearly all the structures located within the investigated urbanized area and, in many cases, also portions of the same building. The improved coherent pixel spatial densities, combined with the reduced revisit times of the new X-band SAR missions, allow us to significantly increase the effectiveness of the advanced DInSAR methodologies, further extending the role of those Earth Observation data in the development of monitoring scenarios.
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Papers by Michele Manunta