Fabio Radicioni

Using C/X-band SAR interferometry and GNSS measurements for the Assisi landslide analysis

This work presents an analysis of the applicability of synthetic aperture radar (SAR) interferometry to landslide monitoring. This analysis was carried out by using different interferometric approaches, different spaceborne SAR data (both in the C-band and in the X-band), and in situ global navigation satellite system (GNSS) measurements. In particular, we investigated both the reliability of displacement monitoring and the issues of the cross-comparison and validation of the interferometric synthetic aperture radar (InSAR) results. The work was focused on the slow-moving landslide that affects a relevant part of the urban area of the historical town of Assisi (Italy). A C-band ENVISAT advanced synthetic aperture radar (ENVISAT ASAR) dataset acquired between 2003 and 2010 was processed by using two different interferometric techniques, to allow cross-comparison of the obtained displacement maps. Good correspondence between the results was found, and a deeper analysis of the movement field was possible. Results were further compared to a set of GNSS measurements with a 7 year overlap with SAR data. A comparison was made for each GNSS marker with the surrounding SAR scatterers, trying to take into account local topological effects, when possible. Further, the high-resolution X-band acquired on both ascending and descending tracks by the COSMO-SkyMed (CSK) constellation was processed. The resultant displacement fields show good agreement with C-band and GNSS measurements and a sensible increase in the density of measurements.

Automatic three-dimensional features extraction: The case study of L'Aquila for collapse identification after April 06, 2009 earthquake

Abstract This paper illustrates an innovative methodology for post-earthquake collapsed building recognition, based on satellite-image classification methodologies and height variation information. Together, the techniques create a robust classification that seems to yield good results in this application field. In the first part of this study, two different feature extraction methodologies were compared, based respectively on pixel-based and object-oriented approaches. Then the classification results of the most accurate classification methodology. obtained on an eight band WorldView-2 monoscopic image, were completed with height variation information before and after the event. The height difference is calculated, comparing a photogrammetric DSM, obtained using a photogrammetric rigorous orbital model on some EROS-B 0.7 metre across-track stereopairs with a ‘roof model’ before the earthquake.

The Assisi Landslide GPS Network

The surface movements of a landslide involving an urban area of the Assisi town, in central Italy, have been measured since 1995 using the GPS technique. This paper presents some design aspects of the GPS network, and a statistical analysis of three annual survey campaigns.

Impact of Local GNSS Permanent Networks in the Study of Geodynamics in Central Italy

The DICA (Department of Civil and Environmental Engineering) of Perugia University currently operates two local GNSS permanent stations networks in central Italy. These networks supply various types of positioning services, which are currently being used mostly by surveyors and mapping agencies. This kind of networks also have a strong potential for the monitoring of crustal deformations in local areas. In the specific case, such applications are particularly interesting because the covered region (Umbria and central Italy) is characterized by a relevant seismicity

Validation of adaptive control laws using optimization and trajectory sensitivity

In this paper it is proposed an easy-to-use verification and validation method for adaptive control laws that relies on time domain simulations. The problem is set as a trajectory falsification problem that is the search of closed loop trajectories that, starting from a set of admissible initial conditions, reach a set of unsafe states. The falsification is placed as a nonlinear optimization problem whose decision variables are the initial condition of the states and the uncertain parameters of the system. The falsification is performed iteratively using the local gradient of the sensitivity function derived from a linearized model of the system trajectory. The sensitivity function allows computing updated values for the initial condition and for the system parameters such that the updated system trajectory get closer to the user defined unsafe set. A detailed Model Reference Adaptive Control law falsification example applied to an F16 aircraft model is presented to highlight the efficacy of the approach.

Use of aerial multispectral images for spatial analysis of flooded riverbed-alluvial plain systems: the case study of the Paglia River (central Italy)

ABSTRACT Image processing and classification techniques are widely used for land use definition. They can also provide interesting applications in fluvial geomorphology, for outlining morpho-sedimentary features (bars, channels, banks and floodplain) at various temporal stages, in order to monitor the evolution of river systems. Frequent monitoring is especially important for streams, in terms of flood risk in urban areas. This study shows how techniques of supervised analysis can be applied to river systems, also under particular conditions, like after flood events (when large portions of riverbed and alluvial plain are covered with mud). The procedure starts from the classical photogrammetric techniques, based on multispectral classification, and goes on with post processing operations of pixel aggregation and shadow treatment. The classification also uses the elevation information provided by Digital Surface Model produced by photogrammetry. This paper introduces a new technique of remote sensing in fluvial areas that allows for both the identification and classification of the fluvial features in a post flooding condition. Application of the procedure over time permits the evolution of the fluvial dynamics to be monitored in an accurate and inexpensive way, particularly for flood event conditions which lead to major changes in the dynamics of riverbeds.

Spatial analysis of critical fluvial areas from aerial multispectral images: an application to River Paglia (central Italy)

The paper presents the first results of a work aimed to develop automatic procedures, and/or semi-automatic, for the morphological and sedimentary analysis of riverbeds (made through multispectral aerial photographs) and to define the morphological changes (plano-altimetric) of the river, by comparison with previous surveys. The methodology has been applied to an area of study that includes the lower valley of River Paglia (a tributary on right of the River Tiber, in central Italy) where a flood, occurred in November 2012, has produced important morphological changes of the riverbed-floodplain system.

The use GPS database in control networks

Working with GPS, a large amount of data is often produced. In complex works, like the control networks, where many stations are involved, measurements are repeated more and more in time, and post-processing is performed with different softwares and/or options, in order to optimize the solutions; it is therefore very important to carefully archive all data, avoiding any possible mix-up. In practice, this is often not a simple job.