Papers by Jordi J Mallorqui
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, Dec 31, 2023
In this paper we show the applicability of orbital Synthetic Aperture Radar (SAR) Differential In... more In this paper we show the applicability of orbital Synthetic Aperture Radar (SAR) Differential Interferometry (DInSAR) with multiple images for terrain deformation episodes monitoring. This paper is focused on the Coherent Pixels Technique (CPT). This technique has been tested with ERS SAR and ENVISAT ASAR data for the period 1992-2008 from The Itoiz and Yesa reservoirs. These ones, located in Navarra, northern Spain, are constructed gravity dams that stores the water from the Irati and the Urrobi rivers, and the Aragón river respectively. The results has been compared with theoretical results obtained using an analytical model.
In this wo rk an innova tive procedure devoted to expe rimentally validate electromagnetic scatte... more In this wo rk an innova tive procedure devoted to expe rimentally validate electromagnetic scattering theories is presented. A fractal surface has been built as a perfec tly reflecting cardboard-aluminium structure, whose properties have been imposed by a computer simulator and verified by optical measurements. The electromagnetic scattering from such a surface has been measured in controlled environment (anechoic chamber).
Educació social: Revista d'intervenció sòcioeducativa, 1999
espanolSe presenta un desarrollo cuya finalidad es poner a disposicion de personas con discapacid... more espanolSe presenta un desarrollo cuya finalidad es poner a disposicion de personas con discapacidad un servicio que les permita, ante situaciones de alarma, enviar la informacion de su ubicacion geografica a un centro de control, a la vez que se les ofrece una comunicacion de voz y tambien un seguimiento automatico de su posicion. Este servicio esta pensado para aumentar el grado de autonomia de colectivos con discapacidades psiquicas, fisicas o simplemente de personas mayores, que frente a una situacion de indisposicion, desorientacion o perdida puedan contactar con una minima intervencion con un centro de control. EnglishIt is shown a development whose aim is to provide handicapped persons with a service allowing them to report, in alarm situations, their geographical location to a monitoring centre, while they are offered a voice communication as well as an automatic monitoring of their position. This service is been conceived as way of increasing the degree of autonomy of groups of both physically and mentally handicapped persons or even the elderly, so that, when finding themselves in situations of indisposition or disorientation, they can contact a monitoring centre with a minium effort.
ESASP, 2008
Remote Sensing Lab (RSLab) Dept. of Signal Theory & Communications Remote Sensing Lab (RSLab) Dep... more Remote Sensing Lab (RSLab) Dept. of Signal Theory & Communications Remote Sensing Lab (RSLab) Dept. of Signal Theory & Communications • unlike optical imagery, interpretation of radar images is not consistent with common visual perception • most of the tools of image processing are conceived from an "optical" point of view Remote Sensing Lab (RSLab) Dept. of Signal Theory & Communications The brain attaches high information content to vertices, linear structures and edges. Inspired on the human vision system, our workplan to achieve a specific framework for the automatic interpretation of SAR imagery is: • Spot detection, directly applied to ship detection. • Extraction of linear features, directly applied to coastline extraction. • Texture analysis, applied to oil spill detection.
Remote Sensing Applications: Society and Environment, Apr 1, 2022
The Campania region has been recurrently hit by severe landslides in volcanoclastic deposits. The... more The Campania region has been recurrently hit by severe landslides in volcanoclastic deposits. The city of Naples, and in particular the Camaldoli and Agnano hills (Phlegraean Fields), also suffered several landslide crises in weathered volcanoclastic rocks as a consequence of intense rainfalls or wildfires. To identify slope failures phenomena occurred in the winter season 2019-2020 an innovative procedure has been proposed. The purpose of this procedure is to highlight areas where major land cover changes occurred within our area of study, which can be potentially related to mass movements. The amplitude of spaceborne SAR images has been exploited for the change detection analysis and the output derived from the segmentation procedure has been compared with field observations. The amplitude-based method has been already applied in the detection of landslides, but never on the event with limited extensions, such as for this application. The achieved outcomes allowed the mapping of 62 new landslides that have been used to update the current landslide inventory database. This type of information is expected to help decision-makers with land planning and risk assessment.
Envisat & ERS Symposium, Apr 1, 2005
Carrying out an effective control of fishing activities is essential to guarantee a sustainable e... more Carrying out an effective control of fishing activities is essential to guarantee a sustainable exploitation of sea resources. While traditional reconnaissance methods, such as planes and patrol vessels are indispensible, their operation is quite time consuming and costly over the extended regulated areas. On the contrary, satellitebased Synthetic Aperture Radar (SAR) provides a powerful surveillance capability already confirmed by a large amount of investigations and experiments all over the world. Nevertheless, automatic ship detection is still far from perfect. Hence, some efforts are still to be furnished in order to improve on this . In this paper, a novel algorithm for ship detection purposes based on the wavelet transform is presented and tested over simulated and real ENVISAT images.
HAL (Le Centre pour la Communication Scientifique Directe), 2005
ABSTRACT The detection of an isolated localized structure in a noisy background, with no a priori... more ABSTRACT The detection of an isolated localized structure in a noisy background, with no a priori information about its presence, nor its shape presents multiple drawbacks. Nevertheless, this problem is present in a great number of applications as, for instance, ship detection from satellite radar imagery. Conventional algorithms for ship detection are conceived to discriminate an exceptionally bright localized pattern according to an established decision rule, expressed by the determination of a threshold. But the adjustment of thresholds involved in the decision step is complicated and relies on the existence of a considerable contrast between the vessels and the surrounding sea clutter which is not always reached. Thus, a novel method, based on the intrascale dependencies between wavelet coefficients in the different subbands, is proposed, justified and successfully tested on simulated and real images.
About one year of coastal AIS (Automatic Identification System) data are analysed for vessel beha... more About one year of coastal AIS (Automatic Identification System) data are analysed for vessel behaviour. The data are obtained from thousands of vessels along the Dutch North Sea coast including the entrance to the main port of Rotterdam. Vessel behaviour is described by a number of basic indicators that can be obtained directly from the AIS messages or from other sensors like radar. It is investigated here if the indicators may be used in e.g. classification algorithms to detect suspicious vessels for the purpose of maritime and border security. In addition, the AIS data are used for a preliminary assessment of the vessel detection possibilities of the recently launched TerraSAR-X satellite when operating in ScanSAR mode.
Remote Sensing, Aug 21, 2019
Differential SAR Interferometry (DInSAR) has proven its unprecedented ability and merits of monit... more Differential SAR Interferometry (DInSAR) has proven its unprecedented ability and merits of monitoring ground deformation on a large scale with centimeter to millimeter accuracy. However, atmospheric artifacts due to spatial and temporal variations of the atmospheric state often affect the reliability and accuracy of its results. The commonly-known Atmospheric Phase Screen (APS) appears in the interferograms as ghost fringes not related to either topography or deformation. Atmospheric artifact mitigation remains one of the biggest challenges to be addressed within the DInSAR community. State-of-the-art research works have revealed that atmospheric artifacts can be partially compensated with empirical models, point-wise GPS zenith path delay, and numerical weather prediction models. In this study, we implement an accurate and realistic computing strategy using atmospheric reanalysis ERA5 data to estimate atmospheric artifacts. With this approach, the Line-of-Sight (LOS) path along the satellite trajectory and the monitored points is considered, rather than estimating it from the zenith path delay. Compared with the zenith delay-based method, the key advantage is that it can avoid errors caused by any anisotropic atmospheric phenomena. The accurate method is validated with Sentinel-1 data in three different test sites: Tenerife island (Spain), Almería (Spain), and Crete island (Greece). The effectiveness and performance of the method to remove APS from interferograms is evaluated in the three test sites showing a great improvement with respect to the zenith-based approach.
EarthArXiv (California Digital Library), Oct 22, 2021
The Campania region has been recurrently hit by severe landslides in volcanoclastic deposits. The... more The Campania region has been recurrently hit by severe landslides in volcanoclastic deposits. The city of Naples, and in particular the Camaldoli and Agnano hills, also suffered several landslide crises in weathered volcanoclastic rocks as a consequence of intense rainfalls or wildfires. This work provides an updated landslide database for the suburbs of Naples. The obtained database consists of about 1322 landslides considering available information dated back to 1816, identified thanks to the historical newspaper's examination; 62 landslides were recorded between 2019 and 2020. Furthermore, the achieved database is the result of the standardization of available information from different sources, organized in a completely different way. The newly identified phenomena have been recognized thanks to a combination of optical satellite imagery with Google Earth, Sentinel-1 radar satellite imagery and field investigation. The implemented methodology is based on change detection analysis of satellite imagery by using polarimetric features. Subsequently, output derived from the segmentation procedure of satellite images have been compared with field trip observations. The main purpose of this procedure is to emphasize areas where land cover changes, potentially related to slope failures, occur in the Phegraean Fields, facilitating the following possible phases of mapping and/or field survey. Eventually, this type of information is expected to help decision-makers with land planning and risk assessment.
SAR based offset tracking (OT) is an efficient tool for ground deformation observation, and signa... more SAR based offset tracking (OT) is an efficient tool for ground deformation observation, and signal-noise-ratio (SNR) is its common error indicator. However, ground feature variation often weakens the accuracy of OT. In addition, SNR shows the signal reliability instead of result accuracy. Based on amplitude selection, cubic spline interpolation and double offset detecting, an improved OT method has been proposed in this paper. Subsidence caused by mining and GPS data have been employed to evaluate the performance of this scheme with TerraSAR-X data. The results indicate that PL and CH are reduced efficiently, and the error estimated by the proposed method has a higher correlation with real error than SNR in the mountainous area.
Palabras clave deslizamiento; estudio geológicogeotécnico; técnicas gravimétricas; monitorización... more Palabras clave deslizamiento; estudio geológicogeotécnico; técnicas gravimétricas; monitorización desplazamientos; control topográfico; A-DInSAR; Resumen La inestabilidad de ladera que afecta a la villa de Leintz Gatzaga (Gipuzkoa) y su entorno ha producido desde hace siglos daños estructurales en viviendas, muros y viales, que van desde moderados a intensos. Esto ha obligado a ejecutar diferentes actuaciones de reparación y consolidación. Se realiza en este trabajo una discusión geológico/geotécnica de los datos disponibles sobre el deslizamiento que afecta a la ladera, así como de los resultados obtenidos a partir de su monitorización con inclinómetros, piezómetros y fisurómetros en los últimos años. Complementariamente, este deslizamiento ha sido elegido como zona test del proyecto EOSLI-DE, en el que se han desarrollado e implementado metodologías de vigilancia que combinan técnicas terrestres clásicas con Técnicas Avanzadas de Interferometría Diferencial Radar de Satélite (A-DInSAR), además de utilizar técnicas gravimétricas para la el estudio de estructuras bajo superficie. Se describen las actuaciones realizadas en el marco de este proyecto y los resultados obtenidos.
Revista Digital del Cedex, Sep 9, 2015
Palabras clave deslizamiento; estudio geológicogeotécnico; técnicas gravimétricas; monitorización... more Palabras clave deslizamiento; estudio geológicogeotécnico; técnicas gravimétricas; monitorización desplazamientos; control topográfico; A-DInSAR; Resumen La inestabilidad de ladera que afecta a la villa de Leintz Gatzaga (Gipuzkoa) y su entorno ha producido desde hace siglos daños estructurales en viviendas, muros y viales, que van desde moderados a intensos. Esto ha obligado a ejecutar diferentes actuaciones de reparación y consolidación. Se realiza en este trabajo una discusión geológico/geotécnica de los datos disponibles sobre el deslizamiento que afecta a la ladera, así como de los resultados obtenidos a partir de su monitorización con inclinómetros, piezómetros y fisurómetros en los últimos años. Complementariamente, este deslizamiento ha sido elegido como zona test del proyecto EOSLI-DE, en el que se han desarrollado e implementado metodologías de vigilancia que combinan técnicas terrestres clásicas con Técnicas Avanzadas de Interferometría Diferencial Radar de Satélite (A-DInSAR), además de utilizar técnicas gravimétricas para la el estudio de estructuras bajo superficie. Se describen las actuaciones realizadas en el marco de este proyecto y los resultados obtenidos.
Trabajo presentado en la EGU General Assembly 2016 (European Geosciences Union), celebrada en Vie... more Trabajo presentado en la EGU General Assembly 2016 (European Geosciences Union), celebrada en Viena (Austria) del 17 al 22 de abril de 2016.We present new results on the deformation field for La Palma Island in the Canary Archipelago using A-DInSAR analysis of C-Band SAR images from ENVISAT and ERS-2 satellites for a six-year period between years 2004 and 2010. The recent volcanic activity registered in La Palma (at historical and subhistorical times, there have been seven eruptions, in ca. A.D. 1480, 1585, 1646, 1677, 1712, 1949 and 1971) and the absence of any geodetic monitoring system implemented in the Island at the 90¿s converts A-DInSAR studies in an basic information source for the study of surface displacements. From late 90¿s several geodetic studies using GNSS, gravimetry and InSAR techniques has been carried out in the island. We improve previous radar satellite results by increasing the temporal coverage and using more images, which generates a greater interferogram set, and using a recently developed A-DInSAR processing technique which includes an error estimation for the LOS mean velocity and deformation time series (¿Subsidence¿ software, developed by the ¿Universitat Politècnica de Catalunya). Our A-DInSAR results are compared with previous InSAR ones and with GNSS results obtained from campaigns. A discussion and geological interpretation of the results is also presented. Radar images have been provided by ESA through Cat.-1 13933 project.Peer reviewe
Trabajo presentado en el AGU (American Geophysical Union) Fall Meeting: Advancing Earth and Space... more Trabajo presentado en el AGU (American Geophysical Union) Fall Meeting: Advancing Earth and Space Science, celebrado en Washington D.C. (Estados Unidos), del 10 al 14 de diciembre de 2018
Proceedings - 3rd Congress in Geomatics Engineering - CIGeo, 2021
La isla de La Palma es de las de mayor riesgo potencial del archipiélago canario, siendo por tant... more La isla de La Palma es de las de mayor riesgo potencial del archipiélago canario, siendo por tanto importante realizar unestudio en profundidad que permita definir su estado de actividad volcánica. Esto se ha realizado usando observacionesde radar de satélite y una técnica de interpretación original de última generación. Ambas cosas han permitido detectar elinicio de la reactivación volcánica en la isla de La Palma, probablemente décadas antes de una posible erupción. Suevolución temporal muestra una naturaleza cambiante de la deformación volcánica, tanto espacial como temporalmente.El uso de imágenes radar permite obtener resultados con una gran resolución espacial y en un periodo de tiempoprolongado (2009-2020), obteniendo información sobre la naturaleza dinámica de los procesos asociados. Las técnicasgeodésicas empleadas permiten detectar la migración de fluidos inducida por la inyección de magma en profundidad eidentificar la existencia de fuentes de dislocación bajo el volcán C...
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Papers by Jordi J Mallorqui