The current study is an empirical study of preference for campus open space around the drill field on Mississippi State University (MSU) campus. 83 students at Mississippi State University were selected as research objects. Based on the literature review, a research process was designed to employ VEP, content analysis and multivariate analysis---Biplot to explore the interested research problems. The study identified two most preferred landscape scene types - "Legibility" and "Coherence" using Kaplan?s "information processing model". A statistical analysis tool for multivariate analysis-Biplot was used to reveal the landscape preference patterns for campus open space as well as how certain landscape features can contribute these patterns. The study found factors such as gender, educational and cultural background can heavily affect these patterns. The result indicated that "vegetations" including tree, seasonal flowers and open grassland, were the most preferred landscape feature on campus open space. Finally, the limitations of this study were discussed and some recommendations for future landscape preference study were provided.

A irradiação de alimentos frescos pós-colheita tem como interesses principais: inibir a brotação, aumentar a vida útil de prateleira, reduzir ou retardar os danos causados por insetos e doenças, atuando como fungicidas ou inseticidas. Atualmente, há uma grande expansão no interesse por alimentos minimamente processados e a manipulação para preparação destes produtos em estado fresco, incluindo muitos processos (descascamento, limpeza, entre outros) que podem alterar as características essenciais para proteger a saúde pública, ou seja, para que o produto não cause danos à saúde do consumidor. Em razão deste fato, este trabalho teve como objetivo avaliar os efeitos da radiação gama em ervilhas em grão (Pisum sativum L.) in natura, a fim de inibir a brotação e aumentar a vida de prateleira. As ervilhas foram divididas em quatro grupos (n=4 amostras/ grupo), de acordo com a intensidade da radiação: 0 (controle), 150, 300 e 450 Gy. Utilizou-se um irradiador de pesquisa 60Co e após irradiação as ervilhas foram armazenadas a uma temperatura 8 °C e seu aspecto visual, de amadurecimento (sólidos solúveis totais, acidez total titulável e razão entre eles), perda de massa fresca, coloração, textura, pH, umidade e cinzas foram avaliados durante os períodos de 1, 7, 14 e 21 dias após a irradiação. A avaliação do aspecto visual mostrou que a irradiação não alterou significativamente a vida de prateleira dos grãos, e que a dose de 300 Gy aumentou significativamente a germinação das ervilhas. As análises de: aspecto visual, perda de massa fresca, coloração e pH, sofreram interferência devido o processo natural de maturação dos grãos e não pela radiação ionizante. Observou-se que, as doses de radiação gama não influenciaram no teor de cinzas, umidade e textura durante o armazenamento e que a dose de 450 Gy foi insuficiente para inibir a brotação das ervilhas. Assim, com base nos resultados encontrados neste trabalho, conclui-se que doses de radiação gama até 450 Gy não foram suficientes para melhorar a vida útil de prateleira e/ou inibir o brotamento de ervilhas. Portanto, recomenda-se que futuros trabalhos sejam realizados com doses de radiação gama maiores que 450 Gy. / The irradiation of fresh post-harvest foods has as main interests: inhibit sprouting, increase shelf life, reduce or delay damage caused by insects and diseases, acting as fungicides or insecticides. Currently, there is a greater interest in minimally processed foods and handling for the preparation of these products in a fresh state, including many processes (peeling, cleaning, among others) that can alter the characteristics essential to protect public health, product does not cause harm to the consumer\'s health. The objective of this work was to use gamma radiation, where the product was irradiated with final packaging to avoid manipulation of the product to the consumer and to evaluate the effects of the same on peas in grains (Pisum sativum L.), in to sprout and increase shelf life. The peas were submitted to 4 treatments: 0 (control), 150, 300 and 450 Gy, in a 60Co research irradiator, after irradiation stored at 8 °C, being evaluated at 1, 7, 14 and 21 days after irradiation, for the following analyzes: assessments of visual appearance, maturation (total soluble solids, titratable total acidity and ratio), fresh weight loss, coloring, texture, pH, water and ash. By visual evaluation it was observed that the irradiation did not significantly change the shelf life of the grains, and that the dose of 300 Gy increased the germination of the peas. The visual appearance, coloring and pH had interference due to the natural process of grain maturation. The fresh weight loss and increase of soluble solids were proportional to the increase of gamma radiation doses, but the doses of gamma radiation did not influence the content of ash, water and texture during storage and that dose of 450 Gy was not sufficient to inhibit the sprouting of the peas. It is possible to conclude that, with this work, a recommendation that, for the later works, in which one wishes to define the shelf life or to inhibit pea budding, initiate the irradiation of its samples with values above 450 Gy.

Les buissons ligneux forment un modèle végétal clé pour répondreaux préoccupations sociales et environnementales.Usuellement transposé sur le modèle arborescent, leur développementarchitectural reste encore peu compris et peu étudiéau regard de leur qualité visuelle. Pour cerner et anticiper cesattentes, une méthodologie pluridisciplinaire visant le managementde la qualité visuelle des plantes d’ornement est proposée.Elle intègre l’architecture des plantes avec sa plasticité phénotypiqueet la perception de leur apparence visuelle. Sur un rosierbuisson : Rosa hybrida L. ‘Radrazz’, l’étude montre commentl’analyse architecturale avec ses outils de modélisation, l’analysesensorielle et d’image peuvent former un cadre scientifi quecohérent visant cet objectif, et transposable à d’autres taxons.Sur rosiers virtuels, et réels exposés à un gradient lumineux, l’apparencevisuelle peut être caractérisée objectivement au moyend’épreuves sensorielles sur vidéode plante en rotation à différentsstades. La vidéo permet aux sujets une meilleure représentationmentale de la plante en 3D, et ainsi une descriptionplus complète et fi able de l’apparence visuelle ; puis de prédirecette description en intégrant statistiquement l’analyse d’imagede plusieurs facettes de la plante. Certaines variables architecturalespertinentes, et de nombreuses équivalentes, potentiellementintéressantes pour étudier le développement des buissonsau cours de leur cycle de vie, permettent de prédire voire d’expliquerl’élaboration des composantes visuelles d’un cultivar. / Shrubs form a key plant model to meet social and environmentalconcerns. Usually transposed on the tree model, their architecturaldevelopment is still ill-known and understudied to address visualquality. To identify and anticipate such expectations, the visual qualitymanagement of ornamental plants through a multidisciplinarymethodology is proposed. It includes architecture of the plants withits phenotypic plasticity and their visual appearance perception.On a rose bush: Rosa hybrida L. ‘Radrazz’, this work shows howarchitectural analysis with its modeling tools, sensory evaluationand image analysis can form a coherent scientifi c framework toface up to such a purpose, and be transposed for other taxa. Onvirtual rose bushes, and real ones exposed to a light gradient, thevisual appearance can be characterized objectively by means ofsensory tests using rotating plant video at different stages.Thevideo stand enables a better mental representation of the plant 3Dby the subjects, leading to a more complete and reliable descriptionof the plant visual appearance; then to predict this descriptionthrough statistically integrated image analysis of multiple plantfacets. Some relevant architectural variables, with numerousequivalents, potentially interesting to study the architecturaldevelopment of bushes during their life cycle, enabled to predicteven explain how visual components were built for a cultivar. Fora better market responsiveness, this work lays the foundationfor drafting interactive decision and innovation support tools forb

No description available.

I samband med en trafikolycka är det ofta viktigt att återställa platsen till det normala så snabbt som möjligt. Emellanåt måste olycksplatsen dokumenteras för att orsaken till olyckan ska kunna utredas i ett senare skede. Traditionellt har detta arbete utförts genom att fotografera platsen och mäta olika avstånd. På senare tid har även terrester laserskanning kommit att bli ett tillförlitligt alternativ. Med det sagt är det tänkbart att även fotogrammetri och andra typer av laserskanning skulle kunna användas för att uppnå liknande resultat.  Syftet med denna studie är att utforska hur handhållen laserskanning och UAS-fotogrammetri kan användas för att dokumentera en trafikolycka. Detta uppnås genom att utvärdera punktmolnens lägesosäkerhet och visuella kvalitet. Vidare utforskas fördelar och nackdelar med respektive metod, bland annat sett till tidsåtgång och kostnader, för att slutligen komma fram till vilken metod som lämpar sig bäst för att dokumentera en trafikolycka.  En trafikolycka med två inblandade bilar iscensattes och laserskannades till en början med den handhållna laserskannern Leica BLK2GO. Därefter samlades bilder in med den obemannade flygfarkosten Leica Aibot följt av att ett referenspunktmoln skapades med den terrestra laserskannern Leica C10. Genom att jämföra koordinater för kontrollpunkter i referenspunktmolnet med koordinaterna för motsvarande kontrollpunkter i de två andra punktmolnen kunde deras lägesosäkerheter bestämmas. Studiens resultat visar att både punktmolnet som framställdes med handhållen laserskanning och UAS-fotogrammetri har en lägesosäkerhet (standardosäkerhet) i 3D på 0,019 m. Båda metoderna är tillämpliga för att dokumentera en trafikolycka, men jämfört med terrester laserskanning är punktmolnen dock bristfälliga på olika sätt. BLK2GO producerar ett förhållandevis mörkt punktmoln och mörka objekt avbildas sämre än ljusare föremål. I punktmolnet som framställdes med Leica Aibot förekom påtagliga håligheter i bilarnas karosser. Handhållen laserskanning är en tidseffektiv metod medan UAS-fotogrammetri kan utföras till en lägre kostnad. Sammanfattningsvis går det inte att dra någon entydig slutsats om vilken metod som lämpar sig bäst för att dokumentera en trafikolycka. Valet beror på vilka omständigheter som råder på olycksplatsen. / In the event of a traffic accident, it is often important to restore the site to its normal condition as fast as possible. Occasionally, the accident scene must be documented so that the cause of the accident can be investigated at a later stage. Traditionally, this work has been performed by taking pictures of the site and measuring different distances. Lately, terrestrial laser scanning has also become a reliable alternative. With that said, it is possible that photogrammetry and other types of laser scanning also could be utilized to achieve similar results.    The aim of this study is to investigate how handheld laser scanning and UAS photogrammetry can be used to document a traffic accident. This is achieved by examining the positional uncertainty and visual quality of the point clouds. Moreover, the advantages and disadvantages of each method are explored, for instance in terms of time consumption and costs, in order to finally come to a conclusion of which method is best suited for documenting a traffic accident. A traffic accident with two involved cars was staged and initially laser scanned with the handheld laser scanner Leica BLK2GO. Thereafter, pictures were collected with the unmanned aerial vehicle Leica Aibot followed by the creation of a reference point cloud with the terrestrial laser scanner Leica C10. By comparing the coordinates of control points in the reference point cloud with the coordinates of the corresponding control points in the two other point clouds, their positional uncertainty could be determined. The results of the study show that both the point cloud produced by the handheld laser scanner and UAS photogrammetry have a positional uncertainty (standard uncertainty) of 0.019 m. Both methods are applicable for documenting a traffic accident but compared to terrestrial laser scanning, the point clouds are deficient in different ways. BLK2GO produces a relatively dark point cloud and dark objects are reproduced worse than lighter objects. In the point cloud produced by Leica Aibot, there were noticeable cavities in the bodies of the cars. Handheld laser scanning is a time-efficient method while UAS photogrammetry can be performed at a lower cost. In conclusion, it is not possible to arrive at an unambiguous conclusion with regards to which method that is best suited for documenting a traffic accident. The choice depends on the prevailing circumstances at the accident scene.

Ce manuscrit présente les travaux de recherche réalisés au cours de ma thèse, dont le but est de développer des algorithmes de correction d'erreurs dans un décodage numérique d'images et d'assurer un haut niveau de la qualité visuelle des images décodées. Nous avons utilisé des techniques d'analyse statistique pour détecter et dissimuler les artefacts. Une boucle de contrôle de la qualité est implémentée afin de surveiller et de corriger la qualité visuelle de l'image. Le manuscrit comprend six chapitres. Le premier chapitre présente les principales méthodes d'évaluation de la qualité des images trouvées dans l'état de l'art et introduit notre proposition. Cette proposition est en fait un outil de mesure de la qualité des vidéos (OMQV) qui utilise le système visuel humain pour indiquer la qualité visuelle d'une vidéo (ou d'une image). Trois modèles d'OMQV sont conçus. Ils sont basés sur la classification, les réseaux de neurones artificiels et la régression non linéaire, et sont développés dans le deuxième, troisième et quatrième chapitre respectivement. Le cinquièmechapitre présente quelques techniques de dissimulation d'artefacts présents dans l'état de l'art. Le sixième et dernier chapitre utilise les résultats des quatre premiers chapitres pour mettre au point un algorithme de correction d'erreurs dans les images. La démonstration considère uniquement les artefacts flou et bruit et s'appuie sur le filtre de Wiener, optimisé sur le critère du minimum linéaire local de l'erreur quadratique moyenne. Les résultats sont présentés et discutés afin de montrer comment l'OMQV améliore les performances de l'algorithme mis en œuvre pour la dissimulation des artefacts. / This report presents the research conducted during my PhD, which aims to develop an efficient algorithm for correcting errors in a digital image decoding process and ensure a high level of visual quality of decoded images. Statistical analysis techniques are studied to detect and conceal the artefacts. A control loop is implemented for the monitoring of image visual quality. The manuscript consists in six chapters. The first chapter presents the principal state of art image quality assessment methods and introduces our proposal. This proposal consists in a video quality measurement tool (VQMT) using the Human Visual System to indicate the visual quality of a video (or an image). Three statistical learning models of VQMT are designed. They are based on classification, artificial neural networks and non-linear regression and are developed in the second, third and fourth chapter respectively. The fifth chapter presents the principal state of art image error concealment technics. The latter chapter uses the results of the four former chapters to design an algorithm for error concealment in images. The demonstration considers blur and noise artefacts and is based on the Wiener filter optimized on the criterion of local linear minimum mean square error. The results are presented and discussed to show how the VQMT improves the performances of the implemented algorithm for error concealment.

Esta pesquisa investigou a contribuição que o patrimônio cultural edificado exerce na qualidade visual da paisagem urbana a partir da abordagem na área da Percepção Ambiental. Adotou como estudo de caso áreas dos centros históricos de três cidades com diferentes graus de preservação do patrimônio cultural edificado: Piratini, a mais preservada, resultado de legislação urbanística pioneira; São José do Norte, onde o patrimônio cultural edificado foi mais destruído ou descaracterizado e Porto Alegre, onde o patrimônio cultural edificado foi parcialmente preservado. A investigação foi operacionalizada por meio da utilização de métodos qualitativos e quantitativos em duas etapas de investigação. A primeira teve por objetivo reunir subsídios para definir a área de estudo em cada uma das três cidades, e por meio da aplicação da técnica de mapas mentais a usuários dos centros históricos, foram identificadas as imagens fortes positivas e negativas das edificações e espaços urbanos (locais, ruas e praças). A segunda etapa teve como objetivo principal testar as hipóteses desta pesquisa por meio da aplicação de questionários acompanhados de cenas urbanas com diferentes níveis de homogeneidade, escolhidas a partir de critérios estabelecidos a fim de responder os objetivos da investigação. As informações obtidas pelos questionários foram analisadas quantitativamente por meio de freqüências e testes não paramétricos tais como tabulações cruzadas e testes de correlação Spearman. Os resultados obtidos permitiram chegar a conclusões sobre o importante papel que o patrimônio cultural edificado exerce na qualidade visual da paisagem urbana. Esta relevância foi verificada na avaliação da aparência visual das edificações analisadas individualmente pelos seus atributos formais e simbólicos e as suas relações no contexto urbano. Importantes correlações foram encontradas entre a avaliação estética da aparência visual das cenas urbanas e atributos formais de volumetria, fachadas e coberturas. As conclusões desta pesquisa reúnem subsídios relativos às questões da estética urbana, do patrimônio cultural edificado e do planejamento urbano que podem contribuir substancialmente para as políticas públicas nas áreas da preservação do patrimônio cultural, do planejamento urbano e ambiental e na implementação de planos e ações de gestão municipal visando qualificar visualmente a paisagem urbana. / The study investigates the aesthetic contributions of historical buildings on the visual quality of the urban historical centers based on the Environmental Perception approach. The research focused on urban scenes of three cities which present different degrees of historical heritage preservation: Piratini, which is the most preserved among them due to existent legislation; São José do Norte, where most of it historical heritage was destroyed or damaged; and Porto Alegre, where historical heritage was partially preserved. The investigation was operationalised through the application of qualitative and quantitative methods, in two stages. On the first stage, the definition of the study area in each city was carried out through the application of mental maps to users of the historical centers, which allowed the identification of strongest positive and negative images. On the second stage, questionnaires were applied in order to verify the research hypotheses. The data gathered through questionnaires was analyzed by means of non parametric statistics, such as qui square test and Spearman correlation tests. Results allowed to conclude about the important role historical buildings play on the visual quality of the urban scene, verified through the evaluation of visual appearance of the buildings individually analyzed according to their formal and symbolic attributes and their relation with the urban context. Important correlations were found between the aesthetic evaluation of the visual appearance of the urban scenes and the formal attributes volume try, facades and roofs. Conclusions provide substantial support to contribute to urban heritage preservation, environmental and urban planning and implementation of plans and actions for the municipal government in order to achieve visual quality in urban areas located in historical centers.

Esta pesquisa investigou a contribuição que o patrimônio cultural edificado exerce na qualidade visual da paisagem urbana a partir da abordagem na área da Percepção Ambiental. Adotou como estudo de caso áreas dos centros históricos de três cidades com diferentes graus de preservação do patrimônio cultural edificado: Piratini, a mais preservada, resultado de legislação urbanística pioneira; São José do Norte, onde o patrimônio cultural edificado foi mais destruído ou descaracterizado e Porto Alegre, onde o patrimônio cultural edificado foi parcialmente preservado. A investigação foi operacionalizada por meio da utilização de métodos qualitativos e quantitativos em duas etapas de investigação. A primeira teve por objetivo reunir subsídios para definir a área de estudo em cada uma das três cidades, e por meio da aplicação da técnica de mapas mentais a usuários dos centros históricos, foram identificadas as imagens fortes positivas e negativas das edificações e espaços urbanos (locais, ruas e praças). A segunda etapa teve como objetivo principal testar as hipóteses desta pesquisa por meio da aplicação de questionários acompanhados de cenas urbanas com diferentes níveis de homogeneidade, escolhidas a partir de critérios estabelecidos a fim de responder os objetivos da investigação. As informações obtidas pelos questionários foram analisadas quantitativamente por meio de freqüências e testes não paramétricos tais como tabulações cruzadas e testes de correlação Spearman. Os resultados obtidos permitiram chegar a conclusões sobre o importante papel que o patrimônio cultural edificado exerce na qualidade visual da paisagem urbana. Esta relevância foi verificada na avaliação da aparência visual das edificações analisadas individualmente pelos seus atributos formais e simbólicos e as suas relações no contexto urbano. Importantes correlações foram encontradas entre a avaliação estética da aparência visual das cenas urbanas e atributos formais de volumetria, fachadas e coberturas. As conclusões desta pesquisa reúnem subsídios relativos às questões da estética urbana, do patrimônio cultural edificado e do planejamento urbano que podem contribuir substancialmente para as políticas públicas nas áreas da preservação do patrimônio cultural, do planejamento urbano e ambiental e na implementação de planos e ações de gestão municipal visando qualificar visualmente a paisagem urbana. / The study investigates the aesthetic contributions of historical buildings on the visual quality of the urban historical centers based on the Environmental Perception approach. The research focused on urban scenes of three cities which present different degrees of historical heritage preservation: Piratini, which is the most preserved among them due to existent legislation; São José do Norte, where most of it historical heritage was destroyed or damaged; and Porto Alegre, where historical heritage was partially preserved. The investigation was operationalised through the application of qualitative and quantitative methods, in two stages. On the first stage, the definition of the study area in each city was carried out through the application of mental maps to users of the historical centers, which allowed the identification of strongest positive and negative images. On the second stage, questionnaires were applied in order to verify the research hypotheses. The data gathered through questionnaires was analyzed by means of non parametric statistics, such as qui square test and Spearman correlation tests. Results allowed to conclude about the important role historical buildings play on the visual quality of the urban scene, verified through the evaluation of visual appearance of the buildings individually analyzed according to their formal and symbolic attributes and their relation with the urban context. Important correlations were found between the aesthetic evaluation of the visual appearance of the urban scenes and the formal attributes volume try, facades and roofs. Conclusions provide substantial support to contribute to urban heritage preservation, environmental and urban planning and implementation of plans and actions for the municipal government in order to achieve visual quality in urban areas located in historical centers.

Esta pesquisa investigou a contribuição que o patrimônio cultural edificado exerce na qualidade visual da paisagem urbana a partir da abordagem na área da Percepção Ambiental. Adotou como estudo de caso áreas dos centros históricos de três cidades com diferentes graus de preservação do patrimônio cultural edificado: Piratini, a mais preservada, resultado de legislação urbanística pioneira; São José do Norte, onde o patrimônio cultural edificado foi mais destruído ou descaracterizado e Porto Alegre, onde o patrimônio cultural edificado foi parcialmente preservado. A investigação foi operacionalizada por meio da utilização de métodos qualitativos e quantitativos em duas etapas de investigação. A primeira teve por objetivo reunir subsídios para definir a área de estudo em cada uma das três cidades, e por meio da aplicação da técnica de mapas mentais a usuários dos centros históricos, foram identificadas as imagens fortes positivas e negativas das edificações e espaços urbanos (locais, ruas e praças). A segunda etapa teve como objetivo principal testar as hipóteses desta pesquisa por meio da aplicação de questionários acompanhados de cenas urbanas com diferentes níveis de homogeneidade, escolhidas a partir de critérios estabelecidos a fim de responder os objetivos da investigação. As informações obtidas pelos questionários foram analisadas quantitativamente por meio de freqüências e testes não paramétricos tais como tabulações cruzadas e testes de correlação Spearman. Os resultados obtidos permitiram chegar a conclusões sobre o importante papel que o patrimônio cultural edificado exerce na qualidade visual da paisagem urbana. Esta relevância foi verificada na avaliação da aparência visual das edificações analisadas individualmente pelos seus atributos formais e simbólicos e as suas relações no contexto urbano. Importantes correlações foram encontradas entre a avaliação estética da aparência visual das cenas urbanas e atributos formais de volumetria, fachadas e coberturas. As conclusões desta pesquisa reúnem subsídios relativos às questões da estética urbana, do patrimônio cultural edificado e do planejamento urbano que podem contribuir substancialmente para as políticas públicas nas áreas da preservação do patrimônio cultural, do planejamento urbano e ambiental e na implementação de planos e ações de gestão municipal visando qualificar visualmente a paisagem urbana. / The study investigates the aesthetic contributions of historical buildings on the visual quality of the urban historical centers based on the Environmental Perception approach. The research focused on urban scenes of three cities which present different degrees of historical heritage preservation: Piratini, which is the most preserved among them due to existent legislation; São José do Norte, where most of it historical heritage was destroyed or damaged; and Porto Alegre, where historical heritage was partially preserved. The investigation was operationalised through the application of qualitative and quantitative methods, in two stages. On the first stage, the definition of the study area in each city was carried out through the application of mental maps to users of the historical centers, which allowed the identification of strongest positive and negative images. On the second stage, questionnaires were applied in order to verify the research hypotheses. The data gathered through questionnaires was analyzed by means of non parametric statistics, such as qui square test and Spearman correlation tests. Results allowed to conclude about the important role historical buildings play on the visual quality of the urban scene, verified through the evaluation of visual appearance of the buildings individually analyzed according to their formal and symbolic attributes and their relation with the urban context. Important correlations were found between the aesthetic evaluation of the visual appearance of the urban scenes and the formal attributes volume try, facades and roofs. Conclusions provide substantial support to contribute to urban heritage preservation, environmental and urban planning and implementation of plans and actions for the municipal government in order to achieve visual quality in urban areas located in historical centers.

L'objectif de cette thèse est de réaliser des missions diverses de navigation autonome en environnement intérieur et encombré avec des robots terrestres. La perception de l'environnement est assurée par un banc stéréo embarqué sur le robot et permet entre autres de calculer la localisation de l'engin grâce à un algorithme d'odométrie visuelle. Mais quand la qualité de la scène perçue par les caméras est faible, la localisation visuelle ne peut pas être calculée de façon précise. Deux solutions sont proposées pour remédier à ce problème. La première solution est l'utilisation d'une méthode de fusion de données multi-capteurs pour obtenir un calcul robuste de la localisation. La deuxième solution est la prédiction de la qualité de scène future afin d'adapter la trajectoire du robot pour s'assurer que la localisation reste précise. Dans les deux cas, la boucle de commande est basée sur l'utilisation de la commande prédictive afin de prendre en compte les différents objectifs de la mission : ralliement de points, exploration, évitement d'obstacles. Une deuxième problématique étudiée est la navigation par points de passage avec évitement d'obstacles mobiles à partir des informations visuelles uniquement. Les obstacles mobiles sont détectés dans les images puis leur position et vitesse sont estimées afin de prédire leur trajectoire future et ainsi de pouvoir anticiper leur déplacement dans la stratégie de commande. De nombreuses expériences ont été réalisées en situation réelle et ont permis de montrer l'efficacité des solutions proposées. / The aim of this thesis is to perform various autonomous navigation missions in indoor and cluttered environments with mobile robots. The environment perception is ensured by an embedded stereo-rig and a visual odometry algorithm which computes the localization of the robot. However, when the quality of the scene perceived by the cameras is poor, the visual localization cannot be computed with a high precision. Two solutions are proposed to tackle this problem. The first one is the data fusion from multiple sensors to perform a robust computation of the localization. The second solution is the prediction of the future scene quality in order to adapt the robot's trajectory to ensure that the localization remains accurate. In the two cases, the control loop is based on model predictive control, which offers the possibility to consider simultaneously the different objectives of the mission : waypoint navigation, exploration, obstacle avoidance. A second issue studied is waypoint navigation with avoidance of mobile obstacles using only the visual information. The mobile obstacles are detected in the images and their position and velocity are estimated in order to predict their future trajectory and consider it in the control strategy. Numerous experiments were carried out and demonstrated the effectiveness of the proposed solutions.