1,721,073 research outputs found
Analysis and interpretation of the COSMO-SkyMed observations of the 2011 Japan tsunami
No full textThe major outcomes of the analysis of the COSMO-SkyMed (CSK) synthetic aperture radar (SAR) observations of the area hit by the 2011 Japan tsunami are presented. The height of the tsunami waves was such as to cause a widespread inundation of the coastal area. The SAR acquisitions have been performed on March 12 (i.e., one day after the tsunami occurred) and March 13, 2011 in interferometric mode, so that not only the information on the intensity of the radar signals, but also the complex coherence has been used. The interpretation of the available data has allowed us to detect the flooded areas, as well as the receding of the floodwater from March 12 to March 13, 2011 and the presence of the debris floating above the water surface. Moreover, thanks to the high spatial resolution of the CSK images, the presence of floodwater in some urban areas in the Sendai harbor has been revealed by exploiting the information on the coherence. Our interpretations have been confirmed by a couple of optical images used as benchmarks. © 2012 IEEE
Analysis of Cosmo-SkyMed observations of the 2008 flood in Myanmar
No full textTwo Cosmo-SkyMed observations of the inundation occurred in Myanmar on May 2008are analyzed in this paper to study the potentiality of this sensor for flood mapping. The first image is temporally close to the peak of the event, while the other one was acquired one week later. Our study accounts for the physics of the radar return in the presence of water surfaces. In particular, both specular reflection, typical of open water, and double bounce backscattering, typical of forested and urban areas, are considered. From the analysis of the Cosmo-SkyMed images, a map representing the extension of the flood at the time of the first radar acquisition is derived
Thematic mapping at regional scale using SIASGE Radar data at X and L band and optical images
No full textThis work aims to assess the potential of Synthetic Aperture Radar (SAR) data combined with optical data to support local administrations in the knowledge of the land use and land cover at regional scale. In particular, the contribution of data available in the future through the SIASGE project, combining L-band and X-band radar imagery, is assessed in order to produce thematic maps. Moreover, the further contribution brought by C-band has been evaluated. The classification, focused on two regions in the north side of Italy, is driven by the legend of already existing maps tackling the real needs of the land managing authorities. As the combination of data from optical imagery is fundamental to achieve good thematic accuracy, the work has exploited the Support Vector Machine learning technique, which is more suitable than standard statistical parametric approaches in this respect. Concerning the classification step, some algorithmic issues has been faced to improve the results, such as training set selection strategy and data fusion techniques. The work has proved as the multi source data set (SAR and optical) is fairly suitable to produce thematic maps comparable to what already in use at local administrative level, allowing to obtain reliable maps with a classification accuracy in the order of 90 %. © 2011 IEEE
Comparing and combining the capability of detecting earthquake damages in urban areas using SAR and optical data
No full textThe prompt detection, mapping and assessment of urban damages due to earthquakes is a key point, particularly in remote areas or where the infrastructures are not well developed to ensure the necessary communication exchanges or where their operability has strongly decreased as a consequence of the event. The combination of Synthetic Aperture Radar (SAR) data and optical images is a promising and suitable approach. We propose two test cases, the 1999 Izmit (Turkey) and the 2003 Bam (Iran) earthquakes where we investigate the capability to detect urban changes and classify them. Moreover, a comparison with ground based data is also shown
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Multi-temporal segmentation of Cosmo-SkyMed SAR data for flood monitoring
No full textThe short revisit time that characterizes the COSMO-SkyMed mission makes possible the analysis of the evolution of flooding events from satellite radar data. A procedure to monitor an inundation event using multi-temporal COSMO-SkyMed imagery is presented in this paper. The dataset consists of five COSMO-SkyMed observations of a flood event occurred in Northern Italy in 2009. The procedure is principally based on an image segmentation technique, which allows identifying homogeneous regions in order to extract a reliable backscattering value, and on the use of an electromagnetic model to interpret the radar return from the image segments. The results demonstrate the potential and the utility of such a combined use of an electromagnetic scattering model and a segmentation algorithm for inundation monitoring. © 2011 IEEE
Combined use of electromagnetic scattering models, fuzzy logic and mathematical morphology for flood mapping using Cosmo-SkyMed data
No full textThe Cosmo-SkyMed mission offers a unique opportunity to obtain radar images useful for flood mapping, being characterized by high revisit time, thanks to the four satellites that form its constellation. In the context of a study aiming at evaluating the usefulness of Earth Observation data for managing flood events, particularly focused on Cosmo-SkyMed, an algorithm to map flooded areas from synthetic aperture radar imagery has been developed. It is based on methods developed in previous studies and aims at combining an image segmentation technique based on mathematical morphology and the fuzzy logic that allows us to label the identified objects as flooded or non-flooded. The default parameters of the fuzzy classifier are derived from the outputs of well-established electromagnetic scattering models
Monitoring flood evolution in agricultural areas using COSMO-SkyMed data: analysis of the Tuscany inundation of December 2009
No full textSynthetic Aperture Radar (SAR) systems represent the most powerful tool to monitor flood events because of their all-weather capability that allows them to collect suitable images even in cloudy conditions. The quality of the flood monitoring using SAR is increasing thanks to the improved spatial resolution of the new generation of instruments and to the short revisit time of the present and future satellite constellations. To fully exploit these technological advances, the methods to interpret images and produce flood maps must be upgraded, so that an accurate interpretation of the multitemporal radar signature, accounting for system parameters (frequency, polarization, incidence angle) and land cover, becomes very important. The images collected by the COSMO-SkyMed constellation of X-band radars represent an example of the aforesaid technological advances. This paper presents a case study regarding a flood occurred in Tuscany (Central Italy) in 2009 monitored using COSMO-SkyMed data. It is shown that the interpretation of the radar data is not straightforward, especially in the presence of vegetation and should rely on the knowledge about the radar scattering mechanisms implemented into electromagnetic models. The paper discusses the multitemporal radar signatures observed during the event and describes the approach we have followed to account for the electromagnetic background into a semi-automatic data processing system
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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