Meaningful Matches in Stereovision

This paper introduces a statistical method to decide whether two blocks in a pair of of images match reliably. The method ensures that the selected block matches are unlikely to have occurred "just by chance." The new approach is based on the definition of a simple but faithful statistical "background model" for image blocks learned from the image itself. A theorem guarantees that under this model not more than a fixed number of wrong matches occurs (on average) for the whole image. This fixed number (the number of false alarms) is the only method parameter. Furthermore, the number of false alarms associated with each match measures its reliability. This "a contrario" block-matching method, however, cannot rule out false matches due to the presence of periodic objects in the images. But it is successfully complemented by a parameterless "self-similarity threshold." Experimental evidence shows that the proposed method also detects occlusions and incoherent motions due to vehicles and pedestrians in non simultaneous stereo.Comment: IEEE Transactions on Pattern Analysis and Machine Intelligence 99, Preprints (2011) 1-1

Development of atmospheric correction algorithms for very high spectral and spatial resolution images: application to SEOSAT and the FLEX/Sentinel-3 missions

Advanced high spectral and spatial resolution imager spectrometers on board new generation of Earth Observation missions bring new exciting opportunities to the remote sensing scientific community. However, this progress goes hand in hand with new challenges. The exploitation of data acquired from these family of advanced instruments requires new processing algorithms able to deal with these particularities. As part of this evolution, atmospheric correction algorithms - a mandatory processing step applied prior to the Earth surface reflectance data exploitation - must be adapted or reformulated, thereby paying special attention to how atmospheric effects disturb the acquired signal in the spectral and spatial domains. For these reasons, this Thesis aims to develop new atmospheric correction strategies to be applied over very high spectral and spatial resolution data. Following this goal, this Thesis was conducted in the framework of two missions during their development phase: (1) the FLEX/Sentinel–3 tandem space mission (for high spectral resolution data) and, (2) the Ingenio/SEOsat space mission (for high spatial resolution data). In the context of these missions, an additional challenge is introduced when acquiring proximal remote sensing data for their validation. This is especially relevant for the FLEX mission, which is dedicated to monitor the weak Solar Induced Chlorophyll Fluorescence (SIF) signal. Following this motivation, the main objectives of this Thesis are threefold: The first objective involved to analyse atmospheric effects on the Ingenio/SEOsat high spatial and low spectral resolution satellite mission and to propose a new atmospheric correction strategy. This strategy was called Hybrid and combines: (1) a per–pixel atmospheric radiative transfer model inversion technique making use of auxiliary data to characterize the atmospheric state, followed by (2) an image deconvolution technique modelling the atmospheric MTF to correct for atmospheric spatial effects. The Hybrid method was applied to Sentinel–2 data, particularly over bands acquired at 10 m resolution due to its similarities with the Ingenio/SEOsat mission. The second objective involved to define a novel atmospheric correction strategy for the FLEX/Sentinel-3 tandem mission. The proposed strategy is a two-steps method where information from Sentinel-3 instruments, OLCI and SLSTR, is first used in synergy to characterize the aerosol and water vapour presence. The high spectral resolution of FLEX data is subsequently exploited to refine the previously aerosol characterization. As part of this objective, the suitability of all the approximations assumed in the formulation proposed for the atmospheric inversion of FLEX data was validated against the FLEX mission requirements. The third objective involved to develop a strategy that deals with the atmospheric correction of very high spectral and spatial resolution data acquired at lower atmospheric scales such as Unmanned Aerial Vehicles or systems mounted on towers. In this Thesis, it was demonstrated that even when acquiring the signal at proximal remote sensing scale, i.e., few meters from the target oxygen absorption must be compensated to properly estimate SIF within these spectral regions. For this reason, a strategy to compensate for the oxygen absorption while properly dealing with the instrumental spectral response function convolution was presented and tested using simulated data. Altogether, this work identified challenges associated to atmospheric correction when applying to high spatial and especially to very high spectral resolution data. In this Thesis, adequate formulations have been developed to resolve these difficulties, and successful methodologies have been designed for the particular cases of SEOsat (high spatial resolution) and FLEX (high spectral resolution); two future remote sensing space missions that will be launched in the forthcoming years

Gossos amb professió

Treball presentat a l'assignatura de Deontologia i Veterinària Legal (21223

El módulo del generador de escena del Simulador end-to-end de la misión Tándem FLEX/Sentinel-3

La misión FLEX (Fluorescence Explorer) seleccionada como el octavo Earth Explorer de la Agencia Espacial Europea (ESA), permite medir globalmente la emisión de la fluorescencia de la vegetación terrestre. FLEX volará en tándem con el satélite Sentinel-3 (S3) de Copernicus, y así obtendrá la información necesaria para la obtención de la fluorescencia. Como parte de las fases tempranas de la misión tándem FLEX/S3, se ha desarrollado un Simulador End-to-end (FLEX-E). Este documento describe el diseño del Módulo de Generación de Escenas (SGM) de FLEX-E; el SGM es capaz de generar escenas sintéticas complejas 3D, que combinan los efectos de la superficie, la topografía, la atmósfera y la geometría de observación/iluminación. El SGM se basa en la utilización de modelos de transferencia radiativa de vegetación y atmósfera, para generar escenas de radiancia en el techo de la atmosfera en alta resolución espacial y espectral para los múltiples instrumentos de la misión tándem FLEX-S3; el SGM está estructurado en cuatro bloques principales: Definición de la escena, Interacción Escena-Geometría, Modelo de propagación y Remuestreo de la escena. Cada uno de estos bloques se detallan aquí y todo el proceso SGM es demostrado por una escena generada FLEX/S3.

Contrariar el odio : los relatos del odio en los medios digitales y la construcción de discursos alternativos en alumnado de Educación Secundaria

Los relatos del odio son discursos creados contra personas y colectivos. Generan discriminación a partir del estigma, la generalización y la exclusión de la convivencia social. En la era digital la educación es clave para que la formación de una ciudadanía crítica pueda deconstruir los relatos del odio que se difunden online, así como reconstruirlos como contrarrelatos. El presente estudio analiza las competencias para la interpretación crítica de la información digital de 307 alumnos y alumnas de Educación Secundaria ante relatos del odio presentes en las redes sociales. Los resultados muestran un rechazo general hacia los relatos racistas y discriminatorios. A pesar de todo, se detectan dificultades importantes para aportar conocimientos sobre los contextos y para construir contrarrelatos. Por otro lado, una minoría del alumnado se muestra de acuerdo con estos discursos discriminatorios.Els relats de l'odi són discursos creats contra persones i col·lectius. Generen discriminació a partir de l'estigma, la generalització i l'exclusió de la convivència social. En l'era digital l'educació és clau per a la formació d'una ciutadania crítica, que pugui desconstruir els relats de l'odi que es difonen en línia, així com reconstruir-los com contrarelats. El present estudi analitza les competències per a la interpretació crítica de la informació digital, de 307 alumnes i alumnes d'educació secundària davant relats de l'odi presents a les xarxes socials. Els resultats mostren un rebuig general cap als relats racistes i discriminatoris. Malgrat tot, es detecten dificultats importants per aportar coneixements sobre els contextos i per construir contra-relats. D'altra banda, una minoria de l'alumnat es mostra d'acord amb aquests discursos discriminatoris.Hate speech are created against people and communities. They generate discrimination from the stigma, generalisation and exclusion of social coexistence. In the digital era, education is important to train critical citizenry able to counter online hate speech. The present study analyses the critical competences of 307 student of Secondary Education, facing hate speech in social media debates. The results show a general rejection to racist and discriminatory contents. Nevertheless, counter narratives based on strong arguments are not usual. On the other hand, a minority of the students are in agreement with these discriminatory discourses.Les récits de la haine sont des discours créés contre des personnes et chou•lectius. Ils génèrent de la discrimination à partir du stigmate, la généralisation et l'exclusion de la cohabitation sociale. En l'était numérique l'éducation est clé pour la formation d'une citoyenneté critique, qui puisse déconstruire les récits de la haine que se diffusent en ligne, ainsi que les reconstruire comme des contre-récits. La présente étude analyse les concurrences pour l'interprétation critique de l'information numérique, de 307 élèves et élèves d'éducation secondaire devant des récits de la haine présentes aux réseaux sociaux. Les résultats montrent un refus général vers les récits racistes et discriminatoires. Malgré tout, ils se détectent difficultés importantes pour apporter des connaissances sur les contextes et pour bâtir contre-des récits. Par ailleurs, une minorité de l'effectif scolaire se montre d'accord avec ces discours discriminatoires

Imagination, education for the future and democratic culture: Educational policies in the Iberian Peninsula

In a historical moment, where the future is considered a threat, it seems highly relevant to teach the ability to imagine desirable futures. In line with this, Education for the Future (EF), from the Anglo-Saxon tradition, represents a reference to give a response to negative images about the idea of the future. On the other hand, the competences for democratic culture defined by the Council of Europe provide the basis for the elaboration of a theoretical framework that includes the imagination of democratic and sustainable futures as one of its main conceptual axes. Given this theoretical context, this study analyses official documents of public policies carried out in the Iberian context, to examine the treatment of the idea of future in education systems. Specifically, three levels of public policies have been studied: state educational laws, primary education curricula and institutional teacher training policies. The public policies have been analysed using the normative method of content analysis, with a syntactic sampling strategy, calculating the absolute and relative frequency of the units of analysis. Results show that there are few references to the construction of the concept of the future in public policies and suggest that the opportunity to educate others on the imagination of desirable futures may be being wasted