Cadre générique pour le recalage dense combinant un coût dense et et un coût basé sur des correspondances de primitives

National audienceL'estimation dense de correspondances entre deux images est un sujet essentiel de la vision par ordinateur et s'exprime sous plusieurs formes : déformations rigides ou flexibles avec de faibles ou grandes amplitudes de déplacements. De nombreuses solutions spécifiques existent mais aucune méthodologie unifiée n'a été formulée. Cet article propose une nouvelle approche générale qui combine de manière robuste un coût dense par pixel et un coût basé sur des correspondances de primitives. Ce dernier utilise une distance robuste permettant d'exploiter des correspondances de points ou de segments. Les correspondances permettent d'empêcher l'optimisation dense de tomber dans un minimum local. En utilisant un coût dense robuste, associé à une régularisation au second ordre et une détection explicite des auto-occultations, nous obtenons des résultats égalant ou surpassant l'état de l'art pour les applications de flot optique 2D, stéréo à fortes disparité et recalage de surfaces déformables. De plus, le faible couplage des modules permet une grande flexibilité en fonction de l'application

Caméras virtuelles pour la calibration d'un système de réalité augmentée composé d'un écran transparent et deux caméras à champs disjoints

National audienceUne nouvelle méthode de calibration extrinsèque pour systèmes de réalité augmentée sur affichages transparents est proposée. Elle est principalement destinée à un système composé d'un écran semi-transparent, d'une caméra de suivi de l'utilisateur et d'une autre caméra, à champ dis- joints, pour localiser le système au sein de l'environne- ment mais facilement généralisable. L'algorithme se base sur des indications fournies par l'utilisateur sur la projection apparente sur l'écran de points de référence d'un objet connu. Une estimation convexe est calculée grâce à la calibration de caméras virtuelles et sert d'initialisation à un ajustement de faisceaux global. Des expériences sur données synthétiques et réelles montrent le bien-fondé de cette approche. Ceci est une traduction de la publication originale

A Useless Campaign? The Example of a Non-Partisan Candidate in Azerbaijan's Parliamentary Elections

This article analyzes the way a non-partisan (in Azerbaijani: "bitərəf") female candidate who is not related to the dominant party ran her campaign for the Azerbaijani parliament in a largely uncompetitive election process. After briefly discussing the main obstacles experienced by non-partisan candidates during the campaign, I will describe the strategies she used to carry out an alternative campaign in a centrally located constituency in the capital city Baku. In so doing, I will show that if such a campaign might seem alternative in its form according to the local context and promising due to the candidate’s social capital, its background remains fairly classical in terms of the approach adopted and the issues raised, while the outcome turns out disappointing

Parole de narrateurs : Figures de l'énonciation dans le récit français moderne

This thesis argues that the meaning of a literary text lies to a large extent in the specific positioning of its narrator not only vis·a·vis the diegetic world s/he unfolds but also in relation to her/his own discourse. The second point refers to what French linguists call the enonciation as the process of speaking, in opposition to the enonce which is the result of this process. Drawing on serval linguistic and narratological theories such as Emile Benveniste's theory of the enonciation and Gerard Genette's description of the narrative voice, this thesis follows the idea that any narrative is necessarily led by an I, whether s/he declares itself as such or on the contrary hides behind the related events. Against a certain conception of the narrative discourse consisting in postulating a void at the origin of the text, this work argues in favour of an incarnate enunciation. In comparison with other acts of language, the characteristic of the narrative act is to make the reader forget that someone is speaking, but it can be argued that it is largely in the traces of the enunciation that the reader really encounters a text. In other words, a text will offer an aesthetic experience all the greater that it will possess a real enunciative force. In this perspective, it is a question of showing that there is no enunciative void but only a reduction, an increase or a transfer of the vocal presence, acting in a continuum. The narrative has never ceased to explore the possibilities of the continuum, from the feigned disappearance of the narrator to his/her notable presence. The central question here is: who is speaking here, and from where? Consequently, the concepts of place and voice are at the centre of this work, interested in the different degrees of the narrator's presence. The term "narrator" has to be understood as a figure constructed in and by the discourse, following a logic of staging (in French, mise en scene) by which a subject of enunciation strives in its own way to "pitch his voice", to use an expression used by Dominique Rabate about the contemporary narrative but which seems to us appropriate to the whole literature. By closely "listening" to six texts chosen for the strength of their vocality, the analysis thus follows, step by step, the subject of enunciation in the narrative text. The aim will be to make the singular voice of the texts resonate, a voice which makes each of them unique and, at the same time, brings them together towards a common horizon, that of the individual speech as an unfailing intersubjective link within the shared language. The course of the texts has been developed chronologically in order to highlight the process of "radicalization" of the question of enunciation from the beginning of the 20th century to the present day. It is obviously not a matter of saying that this question was less present before than it is today - we are facing a question inherent in language that the mere appearance of a narrator, however classic it may be, is enough to ask. But by looking at a sufficiently broad period, the reader of the thesis will be able to appreciate how the question has become, in contemporary narrative, highly problematic, how the text itself has begun to articulate this in new and more explicit scenarios of the narrative instance. This is particularly evident in Annie Ernaux' latest novel, Memoire de jille, in which the narrator seems to be in search a voice. I describe the writer's effort to flnd her place in the uncettain space of speech through the staging of a dissociated I between narrating subject and narrated subject. This contrasts with the first text studied, Victor Segalen's Les Immemoriaux, where, implicitly, the narrator takes on a defined identity and place resulting from a series of transfers of enunciation aiming at restoring to the Other, the Maori poeple, his word and memory. In between, we encounter various enunciative postures that broaden the spech·um of the narrator's staging modalities. The texts chosen reveal a certain number of figures on this spectrum such as the spokesperson's position, free indirect style, repetition, neutrality or metaphor. Clearly, this work cannot not claim to be exhaustive. The heterogeneity of the corpus is not enough to account for all the possibilities o~fered by this enunciative continuum that allows literature to constantly renew itself. Moreover, my interest was above all of a methodological nature; that is why I decided to devote each chapter to a particular text, introducing the whole by means of a theoretical reflection which then allowed the most immanent and complete approach possible to the works. It seems difficult to consider the problem of enunciation without looking at the texts individually, because it is as a vector of meaning that we have addressed it here. In Victor Segalen's work, the narrator appears as a stranger, at the limit of the impenetrable, worried by the loss of words containing the memory of his Maori people. By establishing a stable and unique linguistic system affecting the French language, Segalen creates an opaque narrative mimicking the hermeticism and rhythm of sacred recitations, with the aim of giving the Maori back their voice. This reversal of the European and Tahitian perspectives is confirmed in my analysis of the different transfers of enunciation by which the narrator moves from the common European place to the place of the Other. Although the narrator only appears halfway through the narrative in the form of an impersonal and collective on (in English, "one"or "we"), the narrator of Les Immemoriaux is extremely present in his narrative. His voice is inserted into the Tahitian landscape in the manner of that of the main protagonist, Terii the reciter, to lead the reader into a completely foreign world where he is constantly losing his bearings. In Jean Giono's Le Chant du monde, my interest lies in the detached status of the voice beyond the subject that carries it. I analyse the traces of this excessive enunciation in the metaphorical discourse of the work, observing how the use of the imaginary constantly overwhelmes the diegetic universe. Metaphor as an organizing principle not only of the diction but also of the action of the novel itself, the hero being led to detach himself from the visible (the referential discourse) and to learn the b-a-ba of poetic life that knows how to go beyond appearances, to realize himself in the fusion with the Night, embodied in the brilliant character Clara the blind. The chapter on Ailleurs by Henri Michaux addresses the question of the unsaid through the analysis of the narrator's effort to present himself under the mask of a scientist from whom nothing escapes except himself in his desire to resemble the other. Thus I identify the true function of the narrative in Ailleurs as the remediation by discourse of the chasm that separates the narrator from the inhabitants of the imaginary countries, a separation represented by the wall in the masturbation episode. A wall reflecting both the obstacle against which the narrator never ceases to come up against in the intercultural experience, and this "unknown close to the known" to which he tries to bring the visited countries back. This study would not have been complete without a mention of the humour of the text, based on a powerful ironic enunciation, the place par excellence of the unspoken and the dissimulation contributing to reinforce the nomadism of Michaux, the subject of the ironic enunciation not knowing, said Jankelevitch, where to "pitch his tent". In Marguerite Duras' La mort dujeune aviateur anglais, I turn to the literary topos of the unspeakability of death. In addition to the removal of the logos implied by the confrontation with death, this text also calls into question the narrative language, whose function of configuring phenomenological time is blocked by the resistance of death represented by "the fact of the grave". Unable to assume a properly narrative enunciation, the subject ends up rejecting the whole language in order to remain in the status of non-subject, the only depositary of the first infra-linguistic experience and therefore of the truth of the perceived phenomenon, which language risks distancing. Hence the importance of the visual medium which occupies a predominant place in the text because of its supposed capacity to stick to reality. In search of elements capable of showing this "secondarity" of language in relation to what is not patt of it but can be traced in the enunciation, I finally examine at the great emotion that characterizes this narrative, an emotion that invites us to listen to the voice of the text, its silences and its cries. Annie Ernaux's autobiography Memoire de fille confronts us with the most problematic aspect of enunciation for those who wish to build a narrative identity, inseparable from an enunciative identity. The narrator of the novel, in fact, is not only looking for a story that brings together all her experiences in a logical narrative, but also a voice. Acknowledging the intrinsic division in the autobiographical narrative between the narrative subject (the woman of 2014) and the narrated subject (the girl of 1958), Ernaux opts for a pronominal dissociation producing a broken and uncertain voice, which resolves at the end of the novel in the definitive assumption of the I, coinciding very significantly with the coming into writing. Even if it is to be hoped that Ernaux will publish a new autobiographical novel in the future, it can in any case be said that Memo ire de fille constitutes, as a narrative of the origins (including the enunciative origin), an ideal conclusion to her oeuvre. All the more ideal as it invites the reader, in a way, to reread the whole work in the light of this founding event. In Lydie Salvayre's Pas pleurer, the narratof' delves into the history of the Spanish civil war through the contrasting accounts of her mother and Georges Bernanos. I show that the emotional impasse in which the nanator finds herself is what the text is in charge of processing on the one hand, and what explains its narrative structure on the other. The enunciative system of the novel reveals the narrator's position as an empathic spokesperson, unintentionally revealing her emotion in the ventriloquist nature of her voice, particularly evident in the random presence of maternal words in the narrative discourse. The emotional charge of the heterolingual statements and the disruption of the situation of communication they imply have led to the idea of an "enunciative letting go" which is confirmed in the contrasting mimicry of the narrator's discourse, attracted sometimes by her mother's linguistic freedom and sometimes by Bernanos' beautiful language, to the point of producing a resolutely Baroque novel. In order to further grasp the literary stakes of this enunciative release, I continue this study with a critical analysis of the Italian, German and English translations of the novel. By chance, the three translations showed three different and gradual enunciative positions, from a logic of renunciation taking as a point of support the only figure of the narrator, to a logic of re/mediation based on that of the author.Thesis (Ph.D.) -- University of Adelaide, School of Humanities, 201

Le sujet de l’expression dans Pas pleurer de Lydie Salvayre : une mise en question de la notion d’ “intériorité” littéraire

In a polyphonic prose that blurs the boundaries between the speaking subject and the spoken subject, and thus resists the formal (that is, written) conventions of narrative, Lydie Salvayre, a former psychiatrist, plunges the reader into the “raw” stories of her narrators, as they would present themselves in a psychoanalytical session. In her latest novel Pas pleurer, the narrator, the daughter of Spanish refugees, sets out to grasp the extraordinary singularity of a historical event that conditioned her own existence, that is the beginnings of the civil war in Spain, elucidating the emotions excited in her by the highly contrasted testimonies of her mother and of the writer Georges Bernanos, of whom she is literally the spokesperson throughout the novel. On the basis of an analysis of enunciation in reported speech and of the related phenomena of intertextuality and heterolinguism, this article seeks to highlight the narrative processes that make it possible to “trace” the narrator as the narrative evolves. Thus, this study tries to show that, paradoxically, it is in a certain letting-go of writing, or in escaping towards an exterior perspective that the narrator of Pas pleurer demonstrates her 'interiority', creating that place of narration of inter-individual experience where literature happens

Traduction et hétérolinguisme : une étude comparative de trois traductions de Pas pleurer de Lydie Salvayre

Le cas de l’hétérolinguisme en littérature pose à la traduction la question de son bien-fondé, lorsqu’elle prend le parti du texte source de rater sa cible en exposant le lecteur à une autre langue que la sienne. Cet article examine ce problème à travers une critique comparée des traductions italienne, allemande et anglaise de Pas pleurer de Lydie Salvayre. En mobilisant la notion d’« imaginaire linguistique » (Houdebine), on procédera à l’analyse énonciative des traductions visant à observer, au niveau de l’objet-livre (texte, paratexte, édition), comment est assumée la rupture du contrat linguistique sur lequel repose le geste interprétatif de la traduction et à faire apparaître l’image idéale du lecteur construite dans et par le discours traducteur.The case of heterolingualism in literature questions the principles of translation, when it purports to imitate the cross-language source text and misses its target, by exposing the reader to a third language. This article examines this problem through a comparative critical study of the Italian, German and English translations of Pas pleurer by the French writer Lydie Salvayre. Drawing on Houdebine’s notion of “linguistic imaginary,” the texts will be analysed from an enunciative perspective, in order to understand how the linguistic contract of translation is compromised and also to highlight the ideal image of the reader which is formed in and by the translator’s discourse (text, paratext, edition)

Un atelier de prononciation française pour débutants à l'Université d'Adélaïde

Le présent mémoire présente une étude sur la didactique de la prononciation du français langue étrangère menée à partir d’un projet pédagogique mise en place à l’Université d’Adélaïde en Australie. Le projet visait à enseigner les bases de la prononciation française à des apprenants faux-débutants, en complément de leur formation universitaire principalement centrée sur l’écrit. En prenant appui sur un cadre théorique, le mémoire décrit et analyse la méthodologie utilisée pendant le projet ainsi que les résultats obtenus, dans l’objectif de déterminer les apports didactiques et pédagogiques d’un enseignement explicite de la prononciation française dans l’apprentissage du français langue étrangère

Contributions aux problèmes de l'étalonnage extrinsèque d'affichages semi-transparents pour la réalité augmentée et de la mise en correspondance dense d'images

Augmented reality is the process of inserting virtual elements into a real scene, observed through a screen. Augmented Reality systems can take different forms to get the desired balance between three criteria: accuracy, latency and robustness. Three main components can be identified: localization, reconstruction and display. The contributions of this thesis are focused on display and reconstruction. Most augmented reality systems use non-transparent screens as they are widely available. However, for critical applications such as surgery or driving assistance, the user cannot be ever isolated from reality. We answer this problem by proposing a new “augmented tablet” system with a semi-transparent screen. Such a system needs a suitable calibration scheme:to correctly align the displayed augmentations and reality, one need to know at every moment the poses of the user and the observed scene with regard to the screen. Two tracking devices (user and scene) are thus necessary, and the system calibration aims to compute the pose of those devices with regard to the screen. The calibration process set up in this thesis is as follows: the user indicates the apparent projections in the screen of reference points from a known 3D object ; then the poses to estimate should minimize the 2D on-screen distance between those projections and the ones computed by the system. This is a non-convex problem difficult to solve without a sane initialization. We develop a direct estimation method by computing the extrinsic parameters of virtual cameras. Those are defined by their optical centers which coincide with user positions, and their common focal plane consisting of the screen plane. The user-entered projections are then the 2D observations of the reference points in those virtual cameras. A symmetrical thinking allows one to define virtual cameras centered on the reference points, and “looking at” the user positions. Those initial estimations can then be refined with a bundle adjustment. Meanwhile, 3D reconstruction is based on the triangulation of matches between images. Those matches can be sparse when computed by detection and description of image features or dense when computed through the minimization of a cost function of the whole image. A dense correspondence field is better because it makes it possible to reconstruct a 3D surface, useful especially for realistic handling of occlusions for augmented reality. However, such a field is usually estimated thanks to variational methods, minimizing a convex cost function using local information. Those methods are accurate but subject to local minima, thus limited to small deformations. In contrast, sparse matches can be made very robust by using adequately discriminative descriptors. We propose to combine the advantages of those two approaches by adding a feature-based term into a dense variational method. It helps prevent the optimization from falling into local minima without degrading the end accuracy. Our feature-based term is suited to feature with non-integer coordinates and can handle point or line segment matches while implicitly filtering false matches. We also introduce comprehensive handling of occlusions so as to support large deformations. In particular, we have adapted and generalized a local method for detecting selfocclusions. Results on 2D optical flow and wide-baseline stereo disparity estimation are competitive with the state of the art, with a simpler and most of the time faster method. This proves that our contributions enables new applications of variational methods without degrading their accuracy. Moreover, the weak coupling between the components allows great flexibility and genericness. This is the reason we were able to also transpose the proposed method to the problem of non-rigid surface registration and outperforms the state of the art methods.La réalité augmentée consiste en l'insertion d'éléments virtuels dans une scène réelle, observée à travers un écran. Les systèmes de réalité augmentée peuvent prendre des formes différentes pour obtenir l'équilibre désiré entre trois critères : précision, latence et robustesse. On identifie trois composants principaux : localisation, reconstruction et affichage. Nous nous concentrons sur l'affichage et la reconstruction. Pour certaines applications, l'utilisateur ne peut être isolé de la réalité. Nous proposons un système sous forme de "tablette augmentée" avec un écran semi transparent, au prix d'un étalonnage adapté. Pour assurer l'alignement entre augmentations et réalité, il faut connaître les poses relatives de l'utilisateur et de la scène observée par rapport à l'écran. Deux dispositifs de localisation sont nécessaires et l'étalonnage consiste à calculer la pose de ces dispositifs par rapport à l'écran. Le protocole d'étalonnage est le suivant : l'utilisateur renseigne les projections apparentes dans l'écran de points de référence d'un objet 3D connu ; les poses recherchées minimisent la distance 2D entre ces projections et celles calculées par le système. Ce problème est non convexe et difficile à optimiser. Pour obtenir une estimation initiale, nous développons une méthode directe par l'étalonnage intrinsèque et extrinsèque de caméras virtuelles. Ces dernières sont définies par leurs centres optiques, confondus avec les positions de l'utilisateur, ainsi que leur plan focal, constitué par l'écran. Les projections saisies par l'utilisateur constituent alors les observations 2D des points de référence dans ces caméras virtuelles. Un raisonnement symétrique permet de considérer des caméras virtuelles centrées sur les points de référence de l'objet, "observant" les positions de l'utilisateur. Ces estimations initiales sont ensuite raffinées par ajustement de faisceaux. La reconstruction 3D est basée sur la triangulation de correspondances entre images. Ces correspondances peuvent être éparses lorsqu'elles sont établies par détection, description et association de primitives géométriques ou denses lorsqu'elles sont établies par minimisation d'une fonction de coût sur toute l'image. Un champ dense de correspondance est préférable car il permet une reconstruction de surface, utile notamment pour une gestion réaliste des occultations en réalité augmentée. Les méthodes d'estimation d'un tel champ sont basées sur une optimisation variationnelle, précise mais sensible aux minimums locaux et limitée à des images peu différentes. A l'opposé, l'emploi de descripteurs discriminants peut rendre les correspondances éparses très robustes. Nous proposons de combiner les avantages des deux approches par l'intégration d'un coût basé sur des correspondances éparses de primitives à une méthode d'estimation variationnelle dense. Cela permet d'empêcher l'optimisation de tomber dans un minimum local sans dégrader la précision. Notre terme basé correspondances éparses est adapté aux primitives à coordonnées non entières, et peut exploiter des correspondances de points ou de segments tout en filtrant implicitement les correspondances erronées. Nous proposons aussi une détection et gestion complète des occultations pour pouvoir mettre en correspondance des images éloignées. Nous avons adapté et généralisé une méthode locale de détection des auto-occultations. Notre méthode produit des résultats compétitifs avec l'état de l'art, tout en étant plus simple et plus rapide, pour les applications de flot optique 2D et de stéréo à large parallaxe. Nos contributions permettent d'appliquer les méthodes variationnelles à de nouvelles applications sans dégrader leur performance. Le faible couplage des modules permet une grande flexibilité et généricité. Cela nous permet de transposer notre méthode pour le recalage de surfaces déformables avec des résultats surpassant l'état de l'art, ouvrant de nouvelles perspectives