14 results on '"Tomás, Roberto"'
Search Results
2. Digital 3D Rocks: A Collaborative Benchmark for Learning Rocks Recognition
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Riquelme, Adrián, Cano, Miguel, Tomás, Roberto, Jordá, Luis, Pastor, José Luis, and Benavente, David
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- 2019
- Full Text
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3. Automatic Mapping of Discontinuity Persistence on Rock Masses Using 3D Point Clouds.
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Riquelme, Adrián, Tomás, Roberto, Cano, Miguel, Pastor, José Luis, and Abellán, Antonio
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ROCK analysis , *CLOUD computing , *REMOTE sensing , *PHOTOGRAMMETRY , *OPEN source software , *LIDAR - Abstract
Finding new ways to quantify discontinuity persistence values in rock masses in an automatic or semi-automatic manner is a considerable challenge, as an alternative to the use of traditional methods based on measuring patches or traces with tapes. Remote sensing techniques potentially provide new ways of analysing visible data from the rock mass. This work presents a methodology for the automatic mapping of discontinuity persistence on rock masses, using 3D point clouds. The method proposed herein starts by clustering points that belong to patches of a given discontinuity. Coplanar clusters are then merged into a single group of points. Persistence is measured in the directions of the dip and strike for each coplanar set of points, resulting in the extraction of the length of the maximum chord and the area of the convex hull. The proposed approach is implemented in a graphic interface with open source software. Three case studies are utilized to illustrate the methodology: (1) small-scale laboratory setup consisting of a regular distribution of cubes with similar dimensions, (2) more complex geometry consisting of a real rock mass surface in an excavated cavern and (3) slope with persistent sub-vertical discontinuities. Results presented good agreement with field measurements, validating the methodology. Complexities and difficulties related to the method (e.g., natural discontinuity waviness) are reported and discussed. An assessment on the applicability of the method to the 3D point cloud is also presented. Utilization of remote sensing data for a more objective characterization of the persistence of planar discontinuities affecting rock masses is highlighted herein. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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4. Monitorización de la subsidencia del terreno en la Vega Media del río Segura mediante Interferometría SAR diferencial (DInSAR)
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Tomás, Roberto, Márquez, Yolanda, López Sánchez, Juan Manuel, Delgado, José, Blanco, P., Mallorquí, J. J., Martínez, M., Herrera, G., Mulas de la Peña, J., Universidad de Alicante. Departamento de Ingeniería de la Construcción, Obras Públicas e Infraestructura Urbana, Universidad de Alicante. Departamento de Física, Ingeniería de Sistemas y Teoría de la Señal, Universidad de Alicante. Departamento de Ciencias de la Tierra y del Medio Ambiente, Ingeniería del Terreno y sus Estructuras (InTerEs), Señales, Sistemas y Telecomunicación, and Geología Aplicada e Hidrogeología
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Ground subsidence ,Teoría de la Señal y Comunicaciones ,Piezometric level ,Geotechnical hazard ,Remote sensing ,DInSAR ,Ingeniería del Terreno ,Geodinámica Externa - Abstract
Ground subsidence caused by aquifer exploitation is a geotechnical hazard that affects wide areas, causing important economic damages. This phenomenon is due to soil consolidation produced by the increase of effective stress caused by piezometric depletion. In this work a Remote Sensing Technique called Coherent Pixel (CPT) is applied to monitor subsidence in the Vega Media of the Segura River during a period of eleven years. Este trabajo ha sido financiado por los proyectos TIC2002-04451-C02 y BTE2002-12456-E (MCyT - FEDER), GV04B/556 y GRUPOS03/085 (Generalitat Valenciana) y Cat. 1-2494 (ESA).
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- 2006
5. Monitorización de la subsidencia del terreno en la Vega Media del río Segura mediante Interferometría SAR diferencial (DInSAR)
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Tomás, Roberto, Márquez, Yolanda, López Sánchez, Juan Manuel, Delgado, José, Blanco, P., Mallorquí, J. J., Martínez, M., Herrera, G., and Mulas de la Peña, J.
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Ground subsidence ,Piezometric level ,Geotechnical hazard ,Remote sensing ,DInSAR - Abstract
Ground subsidence caused by aquifer exploitation is a geotechnical hazard that affects wide areas, causing important economic damages. This phenomenon is due to soil consolidation produced by the increase of effective stress caused by piezometric depletion. In this work a Remote Sensing Technique called Coherent Pixel (CPT) is applied to monitor subsidence in the Vega Media of the Segura River during a period of eleven years
- Published
- 2005
6. Imaging Land Subsidence Induced by Groundwater Extraction in Beijing (China) Using Satellite Radar Interferometry.
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Mi Chen, Tomás, Roberto, Zhenhong Li, Motagh, Mahdi, Tao Li, Leyin Hu, Huili Gong, Xiaojuan Li, Jun Yu, and Xulong Gong
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LAND subsidence , *GROUNDWATER , *REMOTE sensing , *SYNTHETIC aperture radar , *SOIL depth - Abstract
Beijing is one of the most water-stressed cities in the world. Due to over-exploitation of groundwater, the Beijing region has been suffering from land subsidence since 1935. In this study, the Small Baseline InSAR technique has been employed to process Envisat ASAR images acquired between 2003 and 2010 and TerraSAR-X stripmap images collected from 2010 to 2011 to investigate land subsidence in the Beijing region. The maximum subsidence is seen in the eastern part of Beijing with a rate greater than 100 mm/year. Comparisons between InSAR and GPS derived subsidence rates show an RMS difference of 2.94 mm/year with a mean of 2.41 ± 1.84 mm/year. In addition, a high correlation was observed between InSAR subsidence rate maps derived from two different datasets (i.e., Envisat and TerraSAR-X). These demonstrate once again that InSAR is a powerful tool for monitoring land subsidence. InSAR derived subsidence rate maps have allowed for a comprehensive spatio-temporal analysis to identify the main triggering factors of land subsidence. Some interesting relationships in terms of land subsidence were found with groundwater level, active faults, accumulated soft soil thickness and different aquifer types. Furthermore, a relationship with the distances to pumping wells was also recognized in this work. [ABSTRACT FROM AUTHOR]
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- 2016
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7. Characterization of rock slopes through slope mass rating using 3D point clouds.
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Riquelme, Adrián J., Tomás, Roberto, and Abellán, Antonio
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ROCK slopes , *PREDICATE calculus , *REMOTE sensing , *DATA modeling , *RELIABILITY in engineering , *COMPUTER software - Abstract
Rock mass classification systems are widely used tools for assessing the stability of rock slopes. Their calculation requires the prior quantification of several parameters during conventional fieldwork campaigns, such as the orientation of the discontinuity sets, the main properties of the existing discontinuities and the geo-mechanical characterization of the intact rock mass, which can be time-consuming and an often risky task. Conversely, the use of relatively new remote sensing data for modelling the rock mass surface by means of 3D point clouds is changing the current investigation strategies in different rock slope engineering applications. In this paper, the main practical issues affecting the application of Slope Mass Rating (SMR) for the characterization of rock slopes from 3D point clouds are reviewed, using three case studies from an end-user point of view. To this end, the SMR adjustment factors, which were calculated from different sources of information and processes, using the different softwares, are compared with those calculated using conventional fieldwork data. In the presented analysis, special attention is paid to the differences between the SMR indexes derived from the 3D point cloud and conventional field work approaches, the main factors that determine the quality of the data and some recognized practical issues. Finally, the reliability of Slope Mass Rating for the characterization of rocky slopes is highlighted. [ABSTRACT FROM AUTHOR]
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- 2016
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8. Subsidence damage assessment of a Gothic church using differential interferometry and field data.
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Tomás, Roberto, García-Barba, Javier, Cano, Miguel, Sanabria, Margarita P, Ivorra, Salvador, Duro, Javier, and Herrera, Gerardo
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STRUCTURAL health monitoring ,GOTHIC church plate ,INTERFEROMETRY ,EFFLORESCENCE ,SOIL consolidation ,INFORMATION theory ,REMOTE sensing ,SPATIAL analysis (Statistics) - Abstract
The Santas Justa and Rufina Gothic church (fourteenth century) has suffered several physical, mechanical, chemical, and biochemical types of pathologies along its history: rock alveolization, efflorescence, biological activity, and capillary ascent of groundwater. However, during the last two decades, a new phenomenon has seriously affected the church: ground subsidence caused by aquifer overexploitation. Subsidence is a process that affects the whole Vega Baja of the Segura River basin and consists of gradual sinking in the ground surface caused by soil consolidation due to a pore pressure decrease. This phenomenon has been studied by differential synthetic aperture radar interferometry techniques, which illustrate settlements up to 100 mm for the 1993–2009 period for the whole Orihuela city. Although no differential synthetic aperture radar interferometry information is available for the church due to the loss of interferometric coherence, the spatial analysis of nearby deformation combined with fieldwork has advanced the current understanding on the mechanisms that affect the Santas Justa and Rufina church. These results show the potential interest and the limitations of using this remote sensing technique as a complementary tool for the forensic analysis of building structures. [ABSTRACT FROM PUBLISHER]
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- 2012
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9. Automated Mapping of Ms 7.0 Jiuzhaigou Earthquake (China) Post-Disaster Landslides Based on High-Resolution UAV Imagery.
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Liang, Rubing, Dai, Keren, Shi, Xianlin, Guo, Bin, Dong, Xiujun, Liang, Feng, Tomás, Roberto, Wen, Ningling, Fan, Xuanmei, and Pirasteh, Saeid
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LANDSLIDES ,LANDSLIDE hazard analysis ,HAZARD mitigation ,REMOTE sensing ,SUPPORT vector machines ,EARTHQUAKES ,AUTOMATIC identification ,ALTITUDES - Abstract
The Ms 7.0 Jiuzhaigou earthquake that occurred on 8 August 2017 triggered hundreds of landslides in the Jiuzhaigou valley scenic and historic-interest area in Sichuan, China, causing heavy casualties and serious property losses. Quick and accurate mapping of post-disaster landslide distribution is of paramount importance for earthquake emergency rescue and the analysis of post-seismic landslides distribution characteristics. The automatic identification of landslides is mostly based on medium- and low-resolution satellite-borne optical remote-sensing imageries, and the high-accuracy interpretation of earthquake-triggered landslides still relies on time-consuming manual interpretation. This paper describes a methodology based on the use of 1 m high-resolution unmanned aerial vehicle (UAV) imagery acquired after the earthquake, and proposes a support vector machine (SVM) classification method combining the roads and villages mask from pre-seismic remote sensing imagery to accurately and automatically map the landslide inventory. Compared with the results of manual visual interpretation, the automatic recognition accuracy could reach 99.89%, and the Kappa coefficient was higher than 0.9, suggesting that the proposed method and 1 m high-resolution UAV imagery greatly improved the mapping accuracy of the landslide area. We also analyzed the spatial-distribution characteristics of earthquake-triggered landslides with the influenced factors of altitude, slope gradient, slope aspect, and the nearest faults, which provided important support for the further study of post-disaster landslide distribution characteristics, susceptibility prediction, and risk assessment. [ABSTRACT FROM AUTHOR]
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- 2021
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10. Multi-Source Data Integration to Investigate a Deep-Seated Landslide Affecting a Bridge.
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Pastor, José Luis, Tomás, Roberto, Lettieri, Luca, Riquelme, Adrián, Cano, Miguel, Infante, Donato, Ramondini, Massimo, and Di Martire, Diego
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LANDSLIDES , *DATA integration , *LIDAR , *REMOTE sensing , *SURVEYING (Engineering) - Abstract
The integration of data from different sources can be very helpful in understanding the mechanism, the geometry, the kinematic, and the area affected by complex instabilities, especially when the available geotechnical information is limited. In this work, the suitability of different techniques for the study of a deep-seated landslide affecting a bridge in Alcoy (Spain) is evaluated. This infrastructure presents such severe damage that has rendered the bridge unusable, which prevents normal access to an important industrial area. Differential SAR Interferometry (DInSAR) and terrestrial Light Detection and Ranging (LiDAR) remote sensing techniques have been combined with ground displacement monitoring techniques, such as inclinometers and conventional geological and geotechnical investigation, electrical-seismic tomography, damage, and topographic surveys, to determine the boundaries, mechanism, and kinematics of the landslide. The successful case study that is illustrated in this work highlights the potential and the need for integrating multi-source data for the optimal management of complex landslides and the effective design of remedial measurements. [ABSTRACT FROM AUTHOR]
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- 2019
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11. Digital landform reconstruction using old and recent open access digital aerial photos.
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Riquelme, Adrián, Del Soldato, Matteo, Tomás, Roberto, Cano, Miguel, Jordá Bordehore, Luis, and Moretti, Sandro
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AERIAL photographs , *DIGITAL photogrammetry , *IMAGE reconstruction , *REMOTE sensing , *GEOMORPHOLOGY - Abstract
Abstract Technological progress in remote sensing has enabled digital representation of terrain through new techniques (e.g. digital photogrammetry) and instruments (e.g. 3D laser scanners). However, the use of old aerial images remains important in geosciences to reconstruct past landforms and detect long-term topographic changes. Administrations have recently expressed growing interest in sharing photogrammetric datasets on public repositories, providing opportunities to exploit these resources and detect natural and anthropogenic topographic changes. The SfM-MVS photogrammetric technique was applied to scanned historical black and white aerial photos of the Serra de Fontcalent (Alicante, Spain), as well as to recent high-quality digital aerial photos. Ground control points (GCPs) extracted from a LiDAR-derived three-dimensional point cloud were used to georeference the results with non-linear deformations. Two point clouds obtained with SfM-MVS were compared with the LiDAR-derived reference point cloud. Based on the result, the quality of the models was analysed through the comparison of the stages on stable areas, i.e., lands where no variations were detected, and active areas, with quarries, new infrastructures, fillings, excavations or new buildings. This study also indicates that errors are higher for old aerial photos (up to 5 m on average) than recent digital photos (up to 0.5 m). The application of SfM-MVS to open access data generated 3D models that enhance the geomorphological analysis, compared to stereophotogrammetry, and effectively detected activities in quarries and building of landfills. Highlights • Existing techniques enable the use of historical and recent aerial photos to reconstruct DEMS • An area of interest is reconstructed using historical printed and digital aerial photos, obtained from readily available resources, through Structure-from-Motion • An airbone LiDAR derived point cloud was used as a benchmark and for the extraction of ground control points • Three different stages of the landform were analysed and compared • The quality of the reconstruction and the capability of monitoring changes were analysed [ABSTRACT FROM AUTHOR]
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- 2019
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12. Comparing manual and remote sensing field discontinuity collection used in kinematic stability assessment of failed rock slopes.
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Jordá Bordehore, Luis, Riquelme, Adrian, Cano, Miguel, and Tomás, Roberto
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ROCK slopes , *REMOTE sensing , *DISCONTINUITIES (Geology) , *ROCK mechanics , *DIGITAL image correlation , *BLOCK theory (Rock mechanics) , *KINEMATICS , *PHOTOGRAMMETRY - Published
- 2017
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13. Using Historical Aerial Photography in Landslide Monitoring: Umka Case Study, Serbia
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Dejan Radovan Đorđević, Uroš Đurić, Saša Tomislav Bakrač, Siniša Milanko Drobnjak, Stevan Radojčić, Calcaterra, Domenico, Di Martire, Diego, Guerriero, Luigi, and Tomás, Roberto
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landslide ,monitoring ,Global and Planetary Change ,Ecology ,processing ,aerial photography ,photography processing ,landslide monitoring ,remote sensing ,aerial ,remote ,photography ,sensing ,Nature and Landscape Conservation - Abstract
The application of remote sensing methods provides useful information that can be used for numerous research. Thus, spatial changes in soil, vegetation, hydrography and such can be analyzed. By analyzing the data obtained by remote sensing methods, high-quality and important data can be obtained for monitoring changes in soil movement caused by landslides. This method provides the possibility of determining the state of the observed space over a longer period of time. Historical aerial imagery has a high level of spatial detail analysis. Comparative analysis of the aerial imagery from the past, recent ones and other surveys can certainly provide information on the trend of ground movement, as well as lead to conclusions for taking specific measures. The present paper gives an example of the analysis of the particular area of the “Umka” landslide based on historical surveys. The “Umka” landslide is located along the right bank of the Sava River near the city of Belgrade, which, with its long-term activity, jeopardizes residential buildings, infrastructure facilities and the population that still lives on it.
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- 2022
14. Combination of multiple remote sensing data for the study of the complex landslide of Agnone (southern Italy).
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Bianchini, Silvia, Del Soldato, Matteo, Riquelme, Adrián, Tomás, Roberto, Martire, Diego Di, De Vita, Pantaleone, Moretti, Sandro, and Calcaterra, Domenico
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LANDSLIDES , *SCIENTIFIC literature , *REMOTE sensing , *REMOTE sensing by radar , *OPTICAL remote sensing , *REMOTE-sensing images - Abstract
The complex landslide of Agnone, located in Molise Region (southern Italy), is a large deep-seated roto-translational slide, involving terrigenous flysch sequences and evolving in the lower portion, in an earth flow. First evidences of landslide activities date back to early 1900s and keep on moving in several time spans up to nowadays. This work illustrates the contribution of multiple optical and radar remote sensing data to landslide investigation approximately across a century as well as to mapping and monitoring ground displacements at the catchment scale.In particular, we firstly revised information from scientific literature and technical reports, compiling monitoring data acquired through inclinometers and geo-morphological surveys in preceding studies to characterize the geological setting of the area. Additionally, we used GPS data acquired from 2010 to 2015 to monitor ground surface motions on some benchmarks of the area. Then, we exploited remotely-sensed data in order to in-depth investigate the spatial and temporal evolution of the landslide-affected catchment.The use of historical air-photos enabled the generation of 3D models by means of the Structure for Motion (SfM) technique to detect, map and monitor unique geomorphological landscapes across several decades. Historical and recent sets of optical photographs from 1945 to 2003 were used in the study area to perform 3D reconstructions and analyze the geomorphological enlargement of the Agnone landslide over 60 years. Radar satellite images acquired by ERS1/2 and ENVISAT constellations at medium spatial resolution, in the spanning time 1992-2010, and by COSMO-SkyMed at high resolution, covering the period 2012-2015, were processed through Persistent Scatterer Interferometry (PSI) techniques. The derived PSI data provided yearly velocities and time series of ground deformation with millimetric accuracy and were exploited for back-monitoring slow surface displacements and for better tracing the boundaries of the mass movement. All data were discussed and used to increase the knowledge about the ground motions affecting the whole Agnone landslide and the surrounding territory. Remotely-sensed data were also compared through in situ field checks to evaluate landslide-induced damage on structures and infrastructures within and close to the landslide body. Outcomes of these analyses demonstrated the operative usefulness of the combination of multi-temporal and multi-technique conventional and remote sensing data for the assessment of spatial and temporal evolution of landslides at basin scale. Moreover, the collected data allowed to plan countermeasures and mitigation actions on the Agnone area according to the distribution and intensity of the detected landslide hazard. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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