La vidéosurveillance a pour objectif principal de protéger les personnes et les biens en détectant tout comportement anormal. Ceci ne serait possible sans la détection de mouvement dans l’image. Ce processus complexe se base le plus souvent sur une opération de soustraction de l’arrière-plan statique d’une scène sur l’image. Mais il se trouve qu’en vidéosurveillance, des caméras sont souvent en mouvement, engendrant ainsi, un changement significatif de l’arrière-plan; la soustraction de l’arrière-plan devient alors problématique. Nous proposons dans ce travail, une méthode de détection de mouvement et particulièrement de chutes qui s’affranchit de la soustraction de l’arrière-plan et exploite la rotation de la caméra dans la détection du mouvement en utilisant le calcul homographique. Nos résultats sur des données synthétiques et réelles démontrent la faisabilité de cette approche. / The main objective of video surveillance is to protect persons and property by detecting any abnormal behavior. This is not possible without detecting motion in the image. This process is often based on the concept of subtraction of the scene background. However in video tracking, the cameras are themselves often in motion, causing a significant change of the background. So, background subtraction techniques become problematic. We propose in this work a motion detection approach, with the example application of fall detection. This approach is free of background subtraction for a rotating surveillance camera. The method uses the camera rotation to detect motion by using homographic calculation. Our results on synthetic and real video sequences demonstrate the feasibility of this approach.

Dans cette thèse, nous introduisons un nouveau modèle instationnaire de vagues valable de la zone de levée à la zone de jet de rive adapté à l'étude de la submersion. Le modèle est basé sur les équations de Serre Green-Naghdi (S-GN), dont l'application à la zone de surf reste un domaine de recherche ouvert. Nous proposons une nouvelle approche pour gérer le déferlement dans ce type de modèle, basée sur la représentation des fronts déferlés par des chocs. Cette approche a été utilisée avec succès pour les modèles basés sur les équations de Saint-Venant (SV) et permet une description simple et efficace du déferlement et des mouvements de la ligne d'eau. Dans ces travaux, nous cherchons à étendre le domaine de validité du modèle SV SURF-WB (Marche et al. 2007) vers la zone de levée en incluant les termes dispersifs propres aux équations de S-GN. Des basculements locaux vers les équations de SV au niveau des fronts permettent alors aux vagues de déferler et dissiper leur énergie. Le modèle obtenu, appelé SURF-GN, est validé à l'aide de données de laboratoire correspondant à différents types de vagues incidentes et de plages. Il est ensuite utilisé pour analyser la dynamique des fronts d'ondes longues de type tsunami en zone littorale. Nous montrons que SURF-GN peut décrire les différents types de fronts, d'ondulé non-déferlé à purement déferlé. Les conséquences de la transformation d'une onde de type tsunami en train d'ondulations lors de la propagation sur une plage sont ensuite considérées. Nous présentons finalement une étude de la célérité des vagues déferlées, basée sur les données de la campagne de mesure in-situ ECORS Truc-Vert 2008. L'influence des non-linéarités est en particulier quantifiée. / In this thesis, we introduce a new numerical model able to describe wave transformation from the shoaling to the swash zones, including overtopping. This model is based on Serre Green-Naghdi equations, which are the basic fully nonlinear Boussinesq-type equations. These equations can accurately describe wave dynamics prior to breaking, but their application to the surf zone usually requires the use of complex parameterizations. We propose a new approach to describe wave breaking in S-GN models, based on the representation of breaking wave fronts as shocks. This method has been successfully applied to the Nonlinear Shallow Water (NSW) equations, and allows for an easy treatment of wave breaking and shoreline motions. However, the NSW equations can only be applied after breaking. In this thesis, we aim at extending the validity domain of the NSW model SURF-WB (Marche et al. 2007) to the shoaling zone by adding the S-GN dispersive terms to the governing equations. Local switches to NSW equations are then performed in the vicinity of the breaking fronts, allowing for the waves to break and dissipate their energy. Extensive validations using laboratory data are presented. The new model, called SURF-GN, is then applied to study tsunami-like undular bore dynamics in the nearshore. The model ability to describe bore dynamics for a large range of Froude number is first demonstrated, and the effects of the bore transformation on wave run-up over a sloping beach are considered. We finally present an in-situ study of broken wave celerity, based on the ECORS-Truc Vert 2008 field experiment. In particular, we quantify the effects of non-linearities and evaluate the predictive ability of several non-linear celerity models.

Master´s thesis deals with methods of objects detection in the image. It contains theoretical, practical and experimental parts. Theoretical part describes image representation, the preprocessing image methods, and methods of detection and identification of objects. The practical part contains a description of the created programs and algorithms which were used in the programs. Application was created in MATLAB. The application offers intuitive graphical user interface and three different methods for the detection and identification of objects in an image. The experimental part contains a test results for an implemented program.

O objetivo deste estudo foi analisar as variações de curta e longa escala temporal na composição e na estrutura da ictiofauna de ambientes praiais e entender os padrões de recrutamento das principais espécies. Seis praias do sistema costeiro Cananéia-Iguape foram amostradas com uma rede de picaré. As amostragens foram realizadas mensalmente de dezembro de 2008 a janeiro de 2010 para as análises de longa escala e a cada dois dias durante um mês de verão para as análises de curto tempo. Independente do foco na variabilidade de curta ou de longa escala, muitas das características da comunidade de peixes permaneceram as mesmas: a predominância de exemplares juvenis, a presença de poucas espécies dominantes e constantes, a alta abundância de Trachinotus e Mugil, e as variações dos índices ecológicos em cada praia ou maré estudada. A influência da temperatura na estrutura da comunidade foi significativa nos estudos de longa escala, mostrando a importância das variações sazonais e do recrutamento nos padrões da comunidade. Juvenis de T. carolinus recrutam ao longo do ano, enquanto T. goodei e Menticirrhus littoralis foram recrutados durante a primavera. M. curema e M. hospes recrutaram durante o verão, enquanto M. liza foi recrutou durante o inverno. Este estudo ressaltou a importância ecológica e econômica da zona rasa de ambientes praias, pois muitas das espécies analisadas na área são importantes recursos pesqueiros para a região. / The aim of this study was to analyze short and long-term temporal variations in ichthyofauna composition and structure from sandy beaches and to understand recruitment patterns of the main species. Six beaches of the coastal system Cananéia-Iguape were sampled using a beach seine. The samples were conducted monthly from December 2008 to January 2010 for a long-term analysis, or every other day during a summer month, for a short-term analysis. Regardless the focus in short or long-term variability, most characteristics of the fish community remained the same: the juvenile fish\'s predominance, the presence few dominant and constant species, the high Trachinotus and Mugil abundance, and the variation of the ecological indexes on each beach and tide studied. The influence of the temperature in the community structure was significant only in the long-term study, showing the seasonal variation and the recruitment importance on the community patterns. T. carolinus juveniles\' recruit all over the year, while T. goodei and Menticirrhus littoralis recruit during spring. M. curema and M. hospes recruit during summer, while M. liza recruit during winter. The present study highlighted the ecological and economic importance of sandy beach shallow zone, as many species analyzed are regional important fishery resources.

O objetivo deste estudo foi analisar as variações de curta e longa escala temporal na composição e na estrutura da ictiofauna de ambientes praiais e entender os padrões de recrutamento das principais espécies. Seis praias do sistema costeiro Cananéia-Iguape foram amostradas com uma rede de picaré. As amostragens foram realizadas mensalmente de dezembro de 2008 a janeiro de 2010 para as análises de longa escala e a cada dois dias durante um mês de verão para as análises de curto tempo. Independente do foco na variabilidade de curta ou de longa escala, muitas das características da comunidade de peixes permaneceram as mesmas: a predominância de exemplares juvenis, a presença de poucas espécies dominantes e constantes, a alta abundância de Trachinotus e Mugil, e as variações dos índices ecológicos em cada praia ou maré estudada. A influência da temperatura na estrutura da comunidade foi significativa nos estudos de longa escala, mostrando a importância das variações sazonais e do recrutamento nos padrões da comunidade. Juvenis de T. carolinus recrutam ao longo do ano, enquanto T. goodei e Menticirrhus littoralis foram recrutados durante a primavera. M. curema e M. hospes recrutaram durante o verão, enquanto M. liza foi recrutou durante o inverno. Este estudo ressaltou a importância ecológica e econômica da zona rasa de ambientes praias, pois muitas das espécies analisadas na área são importantes recursos pesqueiros para a região. / The aim of this study was to analyze short and long-term temporal variations in ichthyofauna composition and structure from sandy beaches and to understand recruitment patterns of the main species. Six beaches of the coastal system Cananéia-Iguape were sampled using a beach seine. The samples were conducted monthly from December 2008 to January 2010 for a long-term analysis, or every other day during a summer month, for a short-term analysis. Regardless the focus in short or long-term variability, most characteristics of the fish community remained the same: the juvenile fish\'s predominance, the presence few dominant and constant species, the high Trachinotus and Mugil abundance, and the variation of the ecological indexes on each beach and tide studied. The influence of the temperature in the community structure was significant only in the long-term study, showing the seasonal variation and the recruitment importance on the community patterns. T. carolinus juveniles\' recruit all over the year, while T. goodei and Menticirrhus littoralis recruit during spring. M. curema and M. hospes recruit during summer, while M. liza recruit during winter. The present study highlighted the ecological and economic importance of sandy beach shallow zone, as many species analyzed are regional important fishery resources.

The SUPERTANK dataset is analyzed to examine the upper limit of beach change in response to elevated water level induced by wave runup. Thirty SUPERTANK runs are investigated, including both erosional and accretionary wave conditions under random and monochromatic waves. Two experiments, one under a spilling and one under a plunging breaker-type, from the Large-Scale Sediment Transport Facility (LSTF) are also analyzed. The upper limit of beach change approximately equals the maximum vertical excursion of swash runup. Exceptions to this direct relationship are those with beach or dune scarps when gravity-driven changes, i.e., avalanching, become significant. The vertical extent of wave runup, Rmax, above mean water level on a beach without a scarp is found to approximately equal the significant breaking wave height, Hbs. Therefore, a simple formula Rmax = Hbs is proposed. The linear relationship between maximum runup and breaking wave height is supported by a conceptual derivation. This predictive formula reproduced the measured runup from a large-scale 3-dimensional movable bed physical model. Beach and dune scarps substantially limit the uprush of swash motion, resulting in a much reduced maximum runup. Predictions of wave runup are not improved by including a slope-dependent surf-similarity parameter. The limit of wave runup is substantially less for monochromatic waves than for random waves, attributed to absence of low-frequency motion for monochromatic waves.

Nearshore processes on barred beaches are studied with a process-based numerical model. The two major goals of the study are to expand the body of knowledge about nearshore processes on barred beaches gaining a better understanding of the physical mechanisms affecting bar migration events and to enhance the numerical model in order to accomplish realistic simulations of bar migration events on storm time scales. The numerical model is used to study the effect of physical processes on the hydrodynamics and morphodynamics in the nearshore environment. The numerical model system consists of a linear spectral refraction-diffraction model, REF/DIF S, a quasi-3D nearshore circulation module, SHORECIRC, energetics-based sediment transport models, and a morphological evolution model. A laboratory experiment with an offshore bar migration case followed by an onshore bar migration case is used for modeling purposes and verifications. A number of enhancements are made to the wave and circulation modules of the numerical model system specifically for simulations on barred beaches. The model modifications and enhancements are: a combined breaking wave parameter with a spatial variation in the wave model, a method accounting for breaking wave persistence in the wave model, a method accounting for the new breaker roller lag in the wave model, the dynamic pressure component in the radiation stress forcing, a roller contribution with different depth variation options for the short wave forcing in the circulation model, wave height instead of water depth as the turbulent length scale in the eddy viscosity calculations in the circulation model, and a slope term for the default sediment transport formula. The effect of surface shape parameter and the roller face angle on radiation stress and mean water level predictions are investigated. In reality, the organized wave energy is transferred to roller development over a transition distance and the roller does not immediately contribute to the radiation stresses; therefore, showing the importance of the roller lag mechanism for mean water level predictions. The cross-shore variation of the vertical momentum balance is studied to observe the variation of forcing agents of the undertow current. The cross-shore pressure gradient is the most dominant forcing term affecting the depth structure of the undertow current. The effect of different depth variations of the roller contribution to the short wave forcing on the undertow current is investigated. The mechanism accounting for breaking wave persistence and the mechanism accounting for the roller lag are shown to be important for predictions of the undertow currents on barred beaches. The skewed wave orbital velocities are introduced to the linear wave model by an empirical parametrization method and are found to contribute strongly to the onshore bar migration. The enhancements made to the wave dissipation and roller are found to significantly affect the predicted migration of the bar as well as the maintainance of the trough.

Στην παρούσα διατριβή παρουσιάζεται η αριθμητική μέθοδος προσομοίωσης μεγάλων κυμάτων (LWS), για τη μελέτη της τυρβώδους ροής που αναπτύσσεται κατά τη θραύση κυμάτων (θραύση εκχείλισης) πάνω από πυθμένα σταθερής κλίσης. Κατά τη μέθοδο LWS, οι μεγάλες κλίμακες των τυρβωδών διακυμάνσεων της ταχύτητας και της ελεύθερης επιφάνειας επιλύονται αριθμητικά, ενώ η επίδραση των μικρών κλιμάκων λαμβάνεται υπόψη με τη χρήση υποπλεγματικού (subgrid scale ή SGS) μοντέλου τάσεων, αντίστοιχο της μεθόδου προσομοίωσης μεγάλων δινών LES. Η θραύση εκχείλισης προσομοιώνεται από τη δράση των SGS τάσεων, οι οποίες δημιουργούν το στρόβιλο θραύσης και παράγουν εγκάρσια στροβιλότητα στο μέτωπο του κύματος. Η μέθοδος LWS εφαρμόζεται σε σύζευξη με τις εξισώσεις Euler και των αντιστοίχων μη-γραμμικών οριακών συνθηκών. Επιπλέον, ως σημείο αναφοράς χρησιμοποιείται η προσομοίωση της θραύσης εκχείλισης με μοντέλο επιφανειακού στροβίλου, κατά το οποίο η επίδραση του στροβίλου θραύσης υπολογίζεται εμπειρικά. Το μοντέλο προσαρμόζεται στις εξισώσεις δισδιάστατης μη συνεκτικής ροής, με τη χρήση κατάλληλα τροποποιημένων οριακών συνθηκών. Παρουσιάζονται αποτελέσματα δισδιάστατης ροής, κατά τη θραύση κύματος κάθετα στην ακτογραμμή, και τρισδιάστατης ροής, κατά τη θραύση κύματος κάθετα και υπό γωνία ως προς την ακτογραμμή. Γενικά, τα αποτελέσματα της ελεύθερης επιφάνειας και του πεδίου ταχυτήτων στη ζώνη απόσβεσης, κατά την θραύση κυμάτων κάθετα στην ακτογραμμή και πάνω από πυθμένα κλίσης 1/35, δείχνουν ικανοποιητική συμφωνία με τις αντίστοιχες πειραματικές μετρήσεις. Ωστόσο, παρά την ασθενή μεταβολή της ροής εγκάρσια στην ακτογραμμή, παρατηρείται ότι, λόγω της τρισδιάστατης δομής του στροβίλου, ο μηχανισμός της θραύσης προσομοιώνεται ικανοποιητικότερα από τη μέθοδο LWS, όταν αυτή συνδυάζεται με τρισδιάστατο πεδίο ροής. Τέλος, εξετάζεται η διάδοση και η θραύση κυμάτων πάνω από πυθμένα σταθερής κλίσης 1/35, τα οποία προσπίπτουν στην ακτογραμμή υπό γωνία 42,45 μοιρών σε μεγάλο βάθος. Οι κορυφογραμμές του κύματος θραύονται σταδιακά και η δράση των SGS τάσεων παράγει εγκάρσια και διαμήκη στροβιλότητα. Ο στρόβιλος θραύσης αναπτύσσεται κατά μήκος των θραυομένων κορυφογραμμών, με γωνία προσανατολισμού αντίστοιχη της γωνίας πρόσπτωσης κύματος στη γραμμή θραύσης. / A method named Large Wave Simulation is presented, for the study of turbulent flow that develops during wave breaking (spilling breakers) over a constant-slope bed. According to LWS method, large scales of velocity field and free-surface elevation are numerically resolved, whereas the corresponding subgrid scale (SGS) effects are accounted for by a SGS stress model, equivalent to the ones used in Large Eddy Simulation (LES) method. Spilling breaking is simulated by a SGS stress field that creates an eddy breaker and produces spanwise vorticity at the breaking wave front. LWS method is used in conjuction with the Euler equation and the corresponding nonlinear boundary conditions. Moreover, as a reference, a surface roller (SR) model is used for the simulation of spilling breaking, which necessitates empirical parameters, for the calculation of the eddy breaker effect. The SR model is adapted for two-dimensional, inviscid but rotational free-surface flow, by use of appropriately modified boundary conditions. Results of two-dimensional flow during breaking waves, propagating perpendicularly to the shoreline, are presented, as well as results of threedimensional flow during breaking waves, propagating perpendicularly and obliquely to the shoreline. In the case of waves breaking perpendicularly to the shoreline over a constant slope (1/35) bed, free-surface elevation and velocities results are in accordance with existing experimental data. However, despite of the flow being weakly dependent to the cross-shore direction, due to the fact that the eddy breaker is three-dimensional, LWS method performs better when combined with a three-dimensional flow field. Finally, oblique wave propagation (42,45 degrees at deep water) and breaking over a constant-slope (1/35) bed is simulated. Wave crestlines break gradually and the effect of the SGS stress field produces spanwise (longshore) and streamwise (cross-shore) vorticity. The eddy breaker develops along the breaking wave front and its orientation follows the shape of the breaking crestlines.

Pratiquer le surf, pour certains, est constitutif de leur identité au sein des mondes contemporains. Surfer et surtout devenir surfeur s'acquiert par une transmission traditionnelle, en dehors des normes fédérales. Être surfeur, c'est un mode de vie particulier, dans les interactions avec les autres pratiquants, dans l'usage avec la nature, dans le rapport au corps, mais aussi dans les questions de masculinité et de féminité. Ce monde singulier, avec une histoire stigmatisante dans certains de ses aspects, est désigné par le reste de la société. Le surf, qui oscille entre le jeu et le sport, par son irrespect des normes et des valeurs dominantes, peut être une réponse aux crises sociales contemporaines. C'est à travers ces failles de la société que s'est infiltré un rapport au monde spécifique des surfeurs : cette culture surfique, qui, dès lors, est considérée comme déviante par le reste de la société.

Com o objetivo de se conhecer a comunidade zooplanctônica da zona de arrebentação da Praia de Tramandaí – RS e identificar a variação sazonal das espécies e sua relação com os padrões de ventos e influências de massas de água, foram realizadas 24 amostragens com intervalo de quinze dias entre agosto de 2005 e agosto de 2006. Dados de temperatura do ar e da água, salinidade, velocidade do vento e direção do vento e da corrente de deriva foram obtidos no campo no momento de cada coleta. A concentração de clorofila-a foi obtida em laboratório, assim como a identificação e quantificação do zooplâncton e sua biomassa em peso seco. Copepoda foi o grupo mais diverso com maior importância representada pela espécie Temora turbinata, seguida de Acartia tonsa e Subeucalanus pileatus. O misidáceo Metamysidopsis elongata atlantica apresentou entre todos os taxa encontrados, a maior freqüência de ocorrência e abundância relativa, correspondendo a grande parte da biomassa em peso seco encontrada. Biomassa de zooplâncton e clorofila-a não apresentaram correlação significativa, apresentando picos de 96 mg.m-³ e 138 μg.L-¹, respectivamente. O copépode Ctenocalanus vanus, apesar de originário de Águas Subantárticas e Subtropicais foi freqüente na região de estudo e a falta de conhecimento sobre seu comportamento e exigências reprodutivas nos levou a realizar testes de laboratório que permitiram observar sua forma de desova e eclosão, assim como estimar valores de produção de ovos, pelotas fecais e náuplios em duas dietas diferentes. Assim os dados levantados servirão de base para novos estudos que permitam um maior entendimento dos processos que ocorrem na coluna d’água da Praia de Tramandaí - RS. / This article aims at the research of the zooplanktonic community of the Tramandaí Beach – RS surf zone and at the identification of the seasonal variation of the species; its relations with wind patterns and water mass influence. To reach such objective, 24 samplings were done between August 2005 and August 2006 at intervals of fifteen days. Data about air and water temperature, salinity, wind speed, drift current, and wind direction were collected in the field at the same time of each sampling. The chlorophyll-a concentration was measured in laboratory as well as the identification and quantification of the zooplankton and its dry biomass. Copepoda was the most diverse group. Temora turbinata was the most important species followed by Acartia tonsa and Subeucalanus pileatus. The Mysidacea Metamysidopsis elongata atlantica expressed the highest frequency of occurrence and relative abundance among all taxa, corresponding to a considerable part of the total dry biomass. Zooplankton biomass and chlorophyll-a did not present significant correlation. The highest concentrations found were 96 mg.m-³ and 138 μg.L-¹ respectively. In spite of being originated in Subtropical and sub-Antarctic waters, the copepod Ctenocalanus vanus was frequently found in the study area. Because of the lack of knowledge about their behaviour and reproductive requirements, we accomplished laboratorial tests which allowed the observation of their kind of spawning and hatching. It also allowed estimating at the number of eggs, fecal pellets and number of nauplius in two different diets. Such data is going to be the basis for new studies to provide a higher understanding of the processes occurring in the water column of Tramandaí Beach - RS