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Cette thèse porte sur le problème de la navigation basée sur la vision pour les robots mobiles dans les environnements intérieurs. Plus récemment, de nombreux travaux ont été réalisés pour résoudre la navigation à l'aide d'un chemin visuel, à savoir la navigation basée sur l'apparence. Cependant, en utilisant ce schéma, le mouvement du robot est limité au chemin visuel d'entrainement. Le risque de collision pendant le processus de navigation peut faire écarter le robot de la trajectoire visuelle courante, pour laquelle les repères visuels peuvent être perdus. Dans l'état de nos connaissances, les travaux envisagent rarement l'évitement des collisions et la perte de repère dans le cadre de la navigation basée sur l'apparence. Nous présentons un cadre mobile de navigation pour le robot afin de renforcer la capacité de la méthode basée sur l'apparence, notamment en cas d'évitement de collision et de contraintes de champ de vision. Notre cadre introduit plusieurs contributions techniques. Tout d'abord, les contraintes de mouvement sont considérés dans la détection de repère visuel pour améliorer la performance de détection. Ensuite, nous modélisons l'obstacle en utilisant B-Spline. La représentation de B-Spline n'a pas de régions accidentées et peut générer un mouvement fluide pour la tâche d'évitement de collision. En outre, nous proposons une stratégie de contrôle basée sur la vision, qui peut gérer la perte complète de la cible. Enfin, nous utilisons l'image sphérique pour traiter le cas des projections d'ambiguité et d'infini dus à la projection en perspective. Les véritables expériences démontrent la faisabilité et l'efficacité de notre cadre et de nos méthodes. / This thesis is concerned with the problem of vision-based navigation for mobile robots in indoor environments. Many works have been carried out to solve the navigation using a visual path, namely appearance-based navigation. However, using this scheme, the robot motion is limited to the trained visual path. The potential collision during the navigation process can make robot deviate from the current visual path, in which the visual landmarks can be lost in the current field of view. To the best of our knowledge, seldom works consider collision avoidance and landmark loss in the framework of appearance-based navigation. We outline a mobile robot navigation framework in order to enhance the capability of appearance-based method, especially in case of collision avoidance and field-of-view constraints. Our framework introduces several technical contributions. First of all, the motion constraints are considered into the visual landmark detection to improve the detection performance. Next then, we model the obstacle boundary using B-Spline. The B-Spline representation has no accidented regions and can generate a smooth motion for the collision avoidance task. Additionally, we propose a vision-based control strategy, which can deal with the complete target loss. Finally, we use spherical image to handle the case of ambiguity and infinity projections due to perspective projection. The real experiments demonstrate the feasability and the effectiveness of our framework and methods.

In this thesis, a novel Object Tracking Algorithm is proposed which tracks objects on Apple iPhone 4 platform in real-time. The system utilizes the colorspace of the frames provided by iPhone camera, in parallel with the motion data provided by iPhone motion sensors, to cancel the effect of iPhone rotations during tracking and matching different candidate tracks. The proposed system also adapts to changes in target appearance and size, thus leading to an object tracking robust to such changes. Several experiments conducted on actual video sequences are used to illustrate the functionality of the proposed approach.

In this thesis, a novel Object Tracking Algorithm is proposed which tracks objects on Apple iPhone 4 platform in real-time. The system utilizes the colorspace of the frames provided by iPhone camera, in parallel with the motion data provided by iPhone motion sensors, to cancel the effect of iPhone rotations during tracking and matching different candidate tracks. The proposed system also adapts to changes in target appearance and size, thus leading to an object tracking robust to such changes. Several experiments conducted on actual video sequences are used to illustrate the functionality of the proposed approach.

Visual object tracking is the task of giving a unique ID to an object in a video frame, understanding whether it is present or not in a current frame and if it is present, precisely localizing its position. There are numerous challenges in object tracking, such as change of illumination, partial or full occlusion, change of target appearance, blurring caused by camera movement, presence of similar objects to the target, changes in video image quality through time, etc. Due to these challenges, traditional computer vision techniques cannot perform high-quality tracking, especially for long-term tracking. Almost all the state-of-the-art methods in object tracking use artificial intelligence nowadays, and more specifically, Convolutional Neural Networks. In this work, we present a Siamese based tracker which is different from previous works in two ways. Firstly, most of the Siamese based trackers takes the target in the first frame as the ground truth. Despite the success of such methods in previous years, it does not guarantee robust tracking as it cannot handle many of the challenges causing change in target appearance, such as blurring caused by camera movement, occlusion, pose variation, etc. In this work, while keeping the first frame as a template, we add five other additional templates that are dynamically updated and replaced considering target classification score in different frames. Diversity, similarity and recency are criteria to choose the members of the bag. We call it as a bag of dynamic templates. Secondly, many Siamese based trackers are vulnerable to mistakenly tracking another similar looking object instead of the intended target. Many researchers proposed computationally expensive approaches, such as tracking all the distractors and the given target and discriminate them in every frame. In this work, we propose an approach to handle this issue by estimate the next frame position by using the target's bounding box coordinates in previous frames. We use temporal network with past history of several previous frames, measure classification scores of candidates considering templates in the bag of dynamic templates and use tracker sequential confidence value which shows how confident the tracker has been in previous frames. We call it as robustifier that prevents the tracker from continuously switching between the target and possible distractors with this hypothesis in mind. Extensive experiments on OTB 50, OTB 100 and UAV20L datasets demonstrate the superiority of our work over the state-of-the-art methods.

Doctor of Philosophy / Department of Computer Science / David A. Gustafson / In this paper we evaluate a general form of image classification algorithm based on dense SIFT sampling. This algorithm is present in some form in most state-of-the-art classification systems. However, in this algorithm, numerous parameters must be tuned, and current research provides little insight into effective parameter tuning. We explore the relationship between various parameters and classification performance. Many of our results suggest that there are basic modifications which would improve state-of-the-art algorithms. Additionally, we develop two novel concepts, sampling redundancy and semantic capacity, to explain our data. These concepts provide additional insight into the limitations and potential improvements of state-of-the-art algorithms.

This thesis is dedicated to the active research topic of generic Visual Object Categorization(VOC), which can be widely used in many applications such as videoindexation and retrieval, video monitoring, security access control, automobile drivingsupport etc. Due to many realistic difficulties, it is still considered to be one ofthe most challenging problems in computer vision and pattern recognition. In thiscontext, we have proposed in this thesis our contributions, especially concerning thetwo main components of the methods addressing VOC problems, namely featureselection and image representation.Firstly, an Embedded Sequential Forward feature Selection algorithm (ESFS)has been proposed for VOC. Its aim is to select the most discriminant features forobtaining a good performance for the categorization. It is mainly based on thecommonly used sub-optimal search method Sequential Forward Selection (SFS),which relies on the simple principle to add incrementally most relevant features.However, ESFS not only adds incrementally most relevant features in each stepbut also merges them in an embedded way thanks to the concept of combinedmass functions from the evidence theory which also offers the benefit of obtaining acomputational cost much lower than the one of original SFS.Secondly, we have proposed novel image representations to model the visualcontent of an image, namely Polynomial Modeling and Statistical Measures basedImage Representation, called PMIR and SMIR respectively. They allow to overcomethe main drawback of the popular "bag of features" method which is the difficultyto fix the optimal size of the visual vocabulary. They have been tested along withour proposed region based features and SIFT. Two different fusion strategies, earlyand late, have also been considered to merge information from different "channels"represented by the different types of features.Thirdly, we have proposed two approaches for VOC relying on sparse representation,including a reconstructive method (R_SROC) as well as a reconstructiveand discriminative one (RD_SROC). Indeed, sparse representation model has beenoriginally used in signal processing as a powerful tool for acquiring, representingand compressing the high-dimensional signals. Thus, we have proposed to adaptthese interesting principles to the VOC problem. R_SROC relies on the intuitiveassumption that an image can be represented by a linear combination of trainingimages from the same category. Therefore, the sparse representations of images arefirst computed through solving the ℓ1 norm minimization problem and then usedas new feature vectors for images to be classified by traditional classifiers such asSVM. To improve the discrimination ability of the sparse representation to betterfit the classification problem, we have also proposed RD_SROC which includes adiscrimination term, such as Fisher discrimination measure or the output of a SVMclassifier, to the standard sparse representation objective function in order to learna reconstructive and discriminative dictionary. Moreover, we have also proposedChapter 0. Abstractto combine the reconstructive and discriminative dictionary and the adapted purereconstructive dictionary for a given category so that the discrimination power canfurther be increased.The efficiency of all the methods proposed in this thesis has been evaluated onpopular image datasets including SIMPLIcity, Caltech101 and Pascal2007.

Generic visual object tracking is the task of tracking one or several objects in all frames in a video, knowing only the location and size of the target in the initial frame. Visual tracking can be carried out in both the infrared and the visual spectrum simultaneously, this is known as multi-modal tracking. Utilizing both spectra can result in a more diverse tracker since visual tracking in infrared imagery makes it possible to detect objects even in poor visibility or in complete darkness. However, infrared imagery lacks the number of details that are present in visual images. A common method for visual tracking is to use discriminative correlation filters (DCF). These correlation filters are then used to detect an object in every frame of an image sequence. This thesis focuses on investigating aspects of a DCF based tracker, operating in the two different modalities, infrared and visual imagery. First, it was investigated whether the tracking benefits from using two channels instead of one and what happens to the tracking result if one of those channels is degraded by an external cause. It was also investigated if the addition of image features can further improve the tracking. The result shows that the tracking improves when using two channels instead of only using a single channel. It also shows that utilizing two channels is a good way to create a robust tracker, which is still able to perform even though one of the channels is degraded. Using deep features, extracted from a pre-trained convolutional neural network, was the image feature improving the tracking the most, although the implementation of the deep features made the tracking significantly slower.

Cette thèse de doctorat est consacrée à un sujet de recherche très porteur : la Catégorisation générique d’objets Visuels (VOC). En effet, les applications possibles sont très nombreuses, incluant l’indexation d’images et de vidéos, la vidéo surveillance, le contrôle d’accès de sécurité, le soutien à la conduite automobile, etc. En raison de ses nombreux verrous scientifiques, ce sujet est encore considéré comme l’un des problèmes les plus difficiles en vision par ordinateur et en reconnaissance de formes. Dans ce contexte, nous avons proposé dans ce travail de thèse plusieurs contributions, en particulier concernant les deux principaux éléments des méthodes résolvant les problèmes de VOC, notamment la sélection des descripteurs et la représentation d’images. Premièrement, un algorithme nomme "Embedded Sequential Forward feature Selection"(ESFS) a été proposé pour VOC. Son but est de sélectionner les descripteurs les plus discriminants afin d’obtenir une bonne performance pour la catégorisation. Il est principalement basé sur la méthode de recherche sous-optimale couramment utilisée "Sequential Forward Selection" (SFS), qui repose sur le principe simple d’ajouter progressivement les descripteurs les plus pertinents. Cependant, ESFS non seulement ajoute progressivement les descripteurs les plus pertinents à chaque étape mais de plus les fusionne d’une manière intégrée grâce à la notion de fonctions de masses combinées empruntée à la théorie de l’évidence qui offre également l’avantage d’obtenir un coût de calcul beaucoup plus faible que celui de SFS original. Deuxièmement, nous avons proposé deux nouvelles représentations d’images pour modéliser le contenu visuel d’une image : la Représentation d’Image basée sur la Modélisation Polynomiale et les Mesures Statistiques, appelées respectivement PMIR et SMIR. Elles permettent de surmonter l’inconvénient principal de la méthode populaire "bag of features" qui est la difficulté de fixer la taille optimale du vocabulaire visuel. Elles ont été testées avec nos descripteurs bases région ainsi que les descripteurs SIFT. Deux stratégies différentes de fusion, précoce et tardive, ont également été considérées afin de fusionner les informations venant des "canaux «différents représentés par les différents types de descripteurs. Troisièmement, nous avons proposé deux approches pour VOC en s’appuyant sur la représentation sparse. La première méthode est reconstructive (R_SROC) alors que la deuxième est reconstructive et discriminative (RD_SROC). En effet, le modèle de représentation sparse a été utilisé originalement dans le domaine du traitement du signal comme un outil puissant pour acquérir, représenter et compresser des signaux de grande dimension. Ainsi, nous avons proposé une adaptation de ces principes intéressants au problème de VOC. R_SROC repose sur l’hypothèse intuitive que l’image peut être représentée par une combinaison linéaire des images d’apprentissage de la même catégorie. [...] / This thesis is dedicated to the active research topic of generic Visual Object Categorization(VOC), which can be widely used in many applications such as videoindexation and retrieval, video monitoring, security access control, automobile drivingsupport etc. Due to many realistic difficulties, it is still considered to be one ofthe most challenging problems in computer vision and pattern recognition. In thiscontext, we have proposed in this thesis our contributions, especially concerning thetwo main components of the methods addressing VOC problems, namely featureselection and image representation.Firstly, an Embedded Sequential Forward feature Selection algorithm (ESFS)has been proposed for VOC. Its aim is to select the most discriminant features forobtaining a good performance for the categorization. It is mainly based on thecommonly used sub-optimal search method Sequential Forward Selection (SFS),which relies on the simple principle to add incrementally most relevant features.However, ESFS not only adds incrementally most relevant features in each stepbut also merges them in an embedded way thanks to the concept of combinedmass functions from the evidence theory which also offers the benefit of obtaining acomputational cost much lower than the one of original SFS.Secondly, we have proposed novel image representations to model the visualcontent of an image, namely Polynomial Modeling and Statistical Measures basedImage Representation, called PMIR and SMIR respectively. They allow to overcomethe main drawback of the popular "bag of features" method which is the difficultyto fix the optimal size of the visual vocabulary. They have been tested along withour proposed region based features and SIFT. Two different fusion strategies, earlyand late, have also been considered to merge information from different "channels"represented by the different types of features.Thirdly, we have proposed two approaches for VOC relying on sparse representation,including a reconstructive method (R_SROC) as well as a reconstructiveand discriminative one (RD_SROC). Indeed, sparse representation model has beenoriginally used in signal processing as a powerful tool for acquiring, representingand compressing the high-dimensional signals. Thus, we have proposed to adaptthese interesting principles to the VOC problem. R_SROC relies on the intuitiveassumption that an image can be represented by a linear combination of trainingimages from the same category. Therefore, the sparse representations of images arefirst computed through solving the ℓ1 norm minimization problem and then usedas new feature vectors for images to be classified by traditional classifiers such asSVM. To improve the discrimination ability of the sparse representation to betterfit the classification problem, we have also proposed RD_SROC which includes adiscrimination term, such as Fisher discrimination measure or the output of a SVMclassifier, to the standard sparse representation objective function in order to learna reconstructive and discriminative dictionary. Moreover, we have also proposedChapter 0. Abstractto combine the reconstructive and discriminative dictionary and the adapted purereconstructive dictionary for a given category so that the discrimination power canfurther be increased.The efficiency of all the methods proposed in this thesis has been evaluated onpopular image datasets including SIMPLIcity, Caltech101 and Pascal2007.

The ʻaudiovisual objectʼ is a fusion of sound object and visual object to create an identifiable perceptual phenomenon, which can be treated as a ʻbuilding blockʼ in the creation of audiovisual work based primarily on electroacoustic composition practice and techniques. This thesis explores how the audiovisual object can be defined and identified in existing works, and offers an examination of how it can be used as a compositional tool. The historical development of the form and the effect of the performance venue on audience immersion is also explored. The audiovisual object concept builds upon theories of electroacoustic composition and film sound design. The audiovisual object is defined in relation to existing concepts of the sound object and visual object, while synaesthesia and cross-modal perception are examined to show how the relationship between sound and vision in the audiovisual object can be strengthened. Electroacoustic composition and animation both developed through technological advances, either the manipulation of recorded sounds, or the manipulation of drawn/photographed objects. The key stages in development of techniques and theories in both disciplines are examined and compared against each other, highlighting correlations and contrasts. The physical space where the audiovisual composition is performed also has a bearing on how the work is perceived and received. Current standard performance spaces include acousmatic concert systems, which emphasize the audio aspect over the visual, and the cinema, which focuses on the visual. Spaces which afford a much higher level of envelopment in the work include hemispheric projection, while individual experience through virtual reality systems could become a key platform. The key elements of the audiovisual object, interaction between objects and their successful use in audiovisual compositions are also investigated in a series of case studies. Specific audiovisual works are examined to highlight techniques to create successful audiovisual objects and interactions. As this research degree is in creative practice, a portfolio of 4 composed works is also included, with production notes explaining the inspiration behind and symbolism within each work, along with the practical techniques employed in their creation. The basis for each work is a short electroacoustic composition which has then been developed with abstract 3D CGI animation into an audiovisual composition, demonstrating the development of my own practice as well as exploring the concept of the audiovisual object. The concept of the audiovisual object draws together existing theories concerning the sound object, visual perception, and phenomenology. The concept, the associated investigation of how audiovisual compositions have evolved over time, and the analysis and critique of case studies based on this central concept contribute both theory and creative practice principles to this form of artistic creativity. This thesis forms a basis for approaching the creative process both as a creator and critic, and opens up a research pathway for further investigation.