FROM CELLULOID REALITIES TO BINARY DREAMSCAPES: CINEMA AND PERCEPTUAL EXPERIENCE IN THE AGE OF DIGITAL IMMERSION

Technologies in digital cinema are quickly changing the way contemporary filmmakers create films and how audiences currently perceive them. As we move onward into the digital turn, it becomes ever more apparent that the medium of film has been emancipated from its dependence on the photograph. Directors are no longer required to capture the objectively real as it sits before the photographic lens, but can essentially construct it via groundbreaking advancements in computer-generated imagery, motion capture technology, and digital 3D camera systems and display technologies. Since the origins of film, spectators and filmmakers have assumed an existing relationship between reality and the photographic image. Yet digital film technologies now provide us with hyper-facsimiles of reality that are perceived as photographic, but are often created by way of computer processes. Digital cinema currently allows the viewer to inhabit and interact with cinematic realities in unprecedented ways, and it is this contemporary paradigmatic shift from the analog to the digital that has catalyzed fundamentally new ways of looking at the filmic image. In this paper, I will examine the perceptual complexities of contemporary digital film through the lens of these cinematic technologies by examining their impact on the viewer’s experience

Optimization techniques for computationally expensive rendering algorithms

Realistic rendering in computer graphics simulates the interactions of light and surfaces. While many accurate models for surface reflection and lighting, including solid surfaces and participating media have been described; most of them rely on intensive computation. Common practices such as adding constraints and assumptions can increase performance. However, they may compromise the quality of the resulting images or the variety of phenomena that can be accurately represented. In this thesis, we will focus on rendering methods that require high amounts of computational resources. Our intention is to consider several conceptually different approaches capable of reducing these requirements with only limited implications in the quality of the results. The first part of this work will study rendering of time-­¿varying participating media. Examples of this type of matter are smoke, optically thick gases and any material that, unlike the vacuum, scatters and absorbs the light that travels through it. We will focus on a subset of algorithms that approximate realistic illumination using images of real world scenes. Starting from the traditional ray marching algorithm, we will suggest and implement different optimizations that will allow performing the computation at interactive frame rates. This thesis will also analyze two different aspects of the generation of anti-­¿aliased images. One targeted to the rendering of screen-­¿space anti-­¿aliased images and the reduction of the artifacts generated in rasterized lines and edges. We expect to describe an implementation that, working as a post process, it is efficient enough to be added to existing rendering pipelines with reduced performance impact. A third method will take advantage of the limitations of the human visual system (HVS) to reduce the resources required to render temporally antialiased images. While film and digital cameras naturally produce motion blur, rendering pipelines need to explicitly simulate it. This process is known to be one of the most important burdens for every rendering pipeline. Motivated by this, we plan to run a series of psychophysical experiments targeted at identifying groups of motion-­¿blurred images that are perceptually equivalent. A possible outcome is the proposal of criteria that may lead to reductions of the rendering budgets

Des preuves récentes sur les habiletés visuo- spatiales pour la formation en chirurgie : revue exploratoire

Background: Understanding the relationships between structures is critical for surgical trainees. However, the heterogeneity of the literature on visual-spatial ability (VSA) in surgery makes it challenging for educators to make informed decisions on incorporating VSA into their programs. We conducted a scoping review of the literature on VSA in surgery to provide a map of the literature and identify where gaps still exist for future research. Methods: We searched databases until December 2019 using keywords related to VSA and surgery. The resulting articles were independently screened by two researchers for inclusion in our review. Results: We included 117 articles in the final review. Fifty-nine articles reported significant correlations between VSA tests and surgical performance, and this association is supported by neuroimaging studies. However, it remains unclear whether VSA should be incorporated into trainee selection and whether there is a benefit of three-dimensional (3D) over two-dimensional (2D) training. Conclusions: It appears that VSA correlates with surgical performance in the simulated environment, particularly for novice learners. Based on our findings, we make suggestions for how surgical educators may use VSA to support novice learners. Further research should determine whether VSA remains correlated to surgical performance when trainees move into the operative environment.Contexte :  Il est fondamental pour les chirurgiens en formation de comprendre les liens qui unissent les diverses structures corporelles. Étant donné l’hétérogénéité de la littérature portant sur les habiletés visuo-spatiales (HVS) nécessaires en chirurgie, les éducateurs ont de la difficulté à prendre des décisions éclairées quant à l’enseignement des HVS dans leurs programmes. On a effectué une étude exploratoire de la littérature sur les HVS en chirurgie afin de répertorier la littérature et de cerner des lacunes pouvant faire l’objet de recherches ultérieures. Méthodologie : On a interrogé des bases de données jusqu’à décembre 2019 à l’aide de mots-clés reliés aux HVS et à la chirurgie.  Les articles trouvés ont été évalués de façon indépendante par deux chercheurs pour déterminer leur inclusion à la revue. Résultats :  Au total, 117 articles ont été inclus dans la revue finale. Cinquante-neuf faisaient état d’importantes corrélations entre les tests d’évaluation des HVS et la performance chirurgicale. Cette association est étayée par les résultats d’études en neuro-imagerie.   Il n’est pas clair cependant si les HVS devraient faire partie des critères de sélection des résidents et si une formation sur les techniques de visualisation en trois dimensions (3D) est préférable à une formation sur les techniques de visualisation en deux dimensions (2D). Conclusions : Il semble exister un lien entre les HVS et la performance chirurgicale en contexte de simulation, particulièrement chez les apprenants novices. À la lumière de nos résultats, nous présentons des recommandations sur la façon dont les formateurs en chirurgie pourraient se servir des HVS pour aider les apprenants novices. D’autres travaux de recherche devraient permettre de savoir si les HVS restent reliés à la performance chirurgicale lorsque les stagiaires passent à un environnement opératoire réel

Visual dysfunction : a contributing factor in memory deficits, and therefore learning difficulties?

This thesis is based on Educational Therapy (ET) practice which has found eye muscle imbalance is a key factor to be addressed in management of learning difficulties (LD). This level of oculo-motor (o-m) function is a \u27hidden\u27 handicap as individuals are unaware of the problem; it is not routinely tested; and is not generally included in learning difficulties research. O-m function is omitted in standard paediatric optometry tests, and in school vision screening. Eye exercises increase the range of binocular fields of vision by employing stereopsis glasses and red/green slides. Central vision loss was uncovered when students reported words, seen by only the right eye, disappear or switch on and off . When the left eye was covered, right eye vision returned but was lost again with binocular vision, even though larger shapes on the screen remained complete. In effect, global vision was unaffected while right eye central (foveal) vision was suppressed. This is considered significant because students attending ET have learning difficulties with phonemic memory, spelling and reading deficits, which are predominantly left hemisphere processes. The aim of this three-part study, consisting of School Survey, ET Intervention study and Case studies, was to: a) determine whether o-m dysfunction was found in a girls\u27 school population and/or was associated with LD; b) set up an Intervention study to explore the effects of vision training on the outcomes of a subsequent week-long word-skills programme in the ET practice. Two case studies we\u27re also examined, that of matched senior school boys whose outcomes were significantly different; and c) examine more closely the common pattern of muscle imbalance in two case studies of current junior school students. This tested the therapy assumption that mal-adaptive sensory feedback was contributing to o-m dysfunction. This notion is based on the Luria (1973) Model of Levels of Neural Function which provides the framework for ET practice, and the Developmental Model of LD that has evolved in application and explanation. Part 1 School Survey. This exploratory, cross-sectional study included a randomised sample of 277 participants in a private girl\u27s school. A 7-10 minute screening was provided by five optometrists, with an expanded protocol including o-m function. Also assessed were academic standards of reading comprehension and spelling, reasoning, visual perception, phonological skills, auditory, visual and phonemic memory, and arm dominance. Results showed visual dysfunction and mixed eye dominance in approximately equal numbers. Of the 47% girls with visual dysfunction, not all had literacy problems; however, LD students had corresponding degrees of o-m dysfunction, memory deficit and mixed hand / arm dominance. Part 2 Intervention study. The Research Question for the Intervention Study was: Does the difference in learning standards depend on which eye is disadvantaged in the case of weak binocularity? This question was answered by determining the outcomes to literacy levels once normal binocular o-m function and stable eye dominance were established. Twenty-four students (6 to 18 years) had Behavioural Optometry assessment prior to commencing therapy and were found to have o-m dysfunction, undetected by previous standard optometry tests. Eye exercise results showed 62.5% of the group had changed from left to right eye dominance. The dominance criterion was set by this group, indicated by the right eye holding fixation through full range of fusional reserves (binocular overlap), together with superior eye-tracking speed \u3e20% by the right, compared to the left, eye. Associated significant gains in literacy and phonemic memory were also achieved by the newly established \u27right-eyed\u27 group. In spite of undergoing identical treatment, the \u27left-eyed\u27 group retained limited foveal binocularity, and made less progress in literacy outcomes. Part 3 Two current Case Studies. Present ET practice benefited from insights gained from the 36% \u27unsuccessful\u27 participants of the previous study. Better therapy outcomes are achieved from an integrative motor-sensory approach, supported by Podiatry and Cranial Osteopathy. This detailed study involved two junior school boys who exemplified a common pattern of physical anomalies. For example, RW (8-year old male) had \u27minimal brain damage\u27 and LD that co-occur with unstable feet and o-m control, postural muscle imbalance, poor balance, motor co-ordination and dyspraxia. After 18, two-hour therapy sessions over nine months, he is now reading well, his motor co-ordination, eye tracking and writing are within the ‘low normal range’, and he is interacting competently with his peers. Learning difficulties can be conceptualised as a profile of immaturities. The results of this three part study have shown that once the \u27hidden\u27 handicap of right eye suppression is overcome with balanced binocular fields of vision, learning difficulties arc ameliorated. This is affirmed by the positive gains achieved by these students, not only in literacy skills but also \u27outgrowing\u27 immaturity in motor-sensory-perceptual development

Une méthode pour l'évaluation de la qualité des images 3D stéréoscopiques.

Dans le contexte d'un intérêt grandissant pour les systèmes stéréoscopiques, mais sans méthodes reproductible pour estimer leur qualité, notre travail propose une contribution à la meilleure compréhension des mécanismes de perception et de jugement humains relatifs au concept multi-dimensionnel de qualité d'image stéréoscopique. Dans cette optique, notre démarche s'est basée sur un certain nombre d'outils : nous avons proposé un cadre adapté afin de structurer le processus d'analyse de la qualité des images stéréoscopiques, nous avons implémenté dans notre laboratoire un système expérimental afin de conduire plusieurs tests, nous avons crée trois bases de données d'images stéréoscopiques contenant des configurations précises et enfin nous avons conduit plusieurs expériences basées sur ces collections d'images. La grande quantité d'information obtenue par l'intermédiaire de ces expérimentations a été utilisée afin de construire un premier modèle mathématique permettant d'expliquer la perception globale de la qualité de la stéréoscopie en fonction des paramètres physiques des images étudiée.In a context of ever-growing interest in stereoscopic systems, but where no standardized algorithmic methods of stereoscopic quality assessment exist, our work stands as a step forward in the understanding of the human perception and judgment mechanisms related to the multidimensional concept of stereoscopic image quality. We used a series of tools in order to perform in-depth investigations in this direction: we proposed an adapted framework to structure the process of stereoscopic quality assessment, we implemented a stereoscopic system in our laboratory for performing various tests, we created three stereoscopic datasets with precise structures, and we performed several experimental studies using these datasets. The numerous experimental data obtained were used in order to propose a first mathematical framework for explaining the overall percept of stereoscopic quality in function of the physical parameters of the stereoscopic images under study.SAVOIE-SCD - Bib.électronique (730659901) / SudocGRENOBLE1/INP-Bib.électronique (384210012) / SudocGRENOBLE2/3-Bib.électronique (384219901) / SudocSudocFranceF

Visual attention models and applications to 3D computer graphics

Ankara : The Department of Computer Engineering and the Graduate School of Engineering and Science of Bilkent University, 2012.Thesis (Ph. D.) -- Bilkent University, 2012.Includes bibliographical refences.3D computer graphics, with the increasing technological and computational opportunities, have advanced to very high levels that it is possible to generate very realistic computer-generated scenes in real-time for games and other interactive environments. However, we cannot claim that computer graphics research has reached to its limits. Rendering photo-realistic scenes still cannot be achieved in real-time; and improving visual quality and decreasing computational costs are still research areas of great interest. Recent e orts in computer graphics have been directed towards exploiting principles of human visual perception to increase visual quality of rendering. This is natural since in computer graphics, the main source of evaluation is the judgment of people, which is based on their perception. In this thesis, our aim is to extend the use of perceptual principles in computer graphics. Our contribution is two-fold: First, we present several models to determine the visually important, salient, regions in a 3D scene. Secondly, we contribute to use of de nition of saliency metrics in computer graphics. Human visual attention is composed of two components, the rst component is the stimuli-oriented, bottom-up, visual attention; and the second component is task-oriented, top-down visual attention. The main di erence between these components is the role of the user. In the top-down component, viewer's intention and task a ect perception of the visual scene as opposed to the bottom-up component. We mostly investigate the bottom-up component where saliency resides. We de ne saliency computation metrics for two types of graphical contents. Our rst metric is applicable to 3D mesh models that are possibly animating, and it extracts saliency values for each vertex of the mesh models. The second metric we propose is applicable to animating objects and nds visually important objects due to their motion behaviours. In a third model, we present how to adapt the second metric for the animated 3D meshes. Along with the metrics of saliency, we also present possible application areas and a perceptual method to accelerate stereoscopic rendering, which is based on binocular vision principles and makes use of saliency information in a stereoscopic rendering scene. Each of the proposed models are evaluated with formal experiments. The proposed saliency metrics are evaluated via eye-tracker based experiments and the computationally salient regions are found to attract more attention in practice too. For the stereoscopic optimization part, we have performed a detailed experiment and veri ed our model of optimization. In conclusion, this thesis extends the use of human visual system principles in 3D computer graphics, especially in terms of saliency.Bülbül, Muhammed AbdullahPh.D

An Empirical Evaluation of Visual Cues for 3D Flow Field Perception

Three-dimensional vector fields are common datasets throughout the sciences. They often represent physical phenomena that are largely invisible to us in the real world, like wind patterns and ocean currents. Computer-aided visualization is a powerful tool that can represent data in any way we choose through digital graphics. Visualizing 3D vector fields is inherently difficult due to issues such as visual clutter, self-occlusion, and the difficulty of providing depth cues that adequately support the perception of flow direction in 3D space. Cutting planes are often used to overcome these issues by presenting slices of data that are more cognitively manageable. The existing literature provides many techniques for visualizing the flow through these cutting planes; however, there is a lack of empirical studies focused on the underlying perceptual cues that make popular techniques successful. The most valuable depth cue for the perception of other kinds of 3D data, notably 3D networks and 3D point clouds, is structure-from-motion (also called the Kinetic Depth Effect); another powerful depth cue is stereoscopic viewing, but none of these cues have been fully examined in the context of flow visualization. This dissertation presents a series of quantitative human factors studies that evaluate depth and direction cues in the context of cutting plane glyph designs for exploring and analyzing 3D flow fields. The results of the studies are distilled into a set of design guidelines to improve the effectiveness of 3D flow field visualizations, and those guidelines are implemented as an immersive, interactive 3D flow visualization proof-of-concept application