A theory of moving form perception: Synergy between masking, perceptual grouping, and motion computation in retinotopic and non-retinotopic representations

Because object and self-motion are ubiquitous in natural viewing conditions, understanding how the human visual system achieves a relatively clear perception for moving objects is a fundamental problem in visual perception. Several studies have shown that the visible persistence of a briefly presented stationary stimulus is approximately 120 ms under normal viewing conditions. Based on this duration of visible persistence, we would expect moving objects to appear highly blurred. However, in human vision, objects in motion typically appear relatively sharp and clear. We suggest that clarity of form in dynamic viewing is achieved by a synergy between masking, perceptual grouping, and motion computation across retinotopic and non-retinotopic representations. We also argue that dissociations observed in masking are essential to create and maintain this synergy

A New Conceptualization of Human Visual Sensory-Memory

Memory is an essential component of cognition and disorders of memory have significant individual and societal costs. The Atkinson-Shiffrin "modal model" forms the foundation of our understanding of human memory. It consists of three stores: Sensory Memory (SM), whose visual component is called iconic memory, Short-Term Memory (STM; also called working memory, WM), and Long-Term Memory (LTM). Since its inception, shortcomings of all three components of the modal model have been identified. While the theories of STM and LTM underwent significant modifications to address these shortcomings, models of the iconic memory remained largely unchanged: A high capacity but rapidly decaying store whose contents are encoded in retinotopic coordinates, i.e., according to how the stimulus is projected on the retina. The fundamental shortcoming of iconic memory models is that, because contents are encoded in retinotopic coordinates, the iconic memory cannot hold any useful information under normal viewing conditions when objects or the subject are in motion. Hence, half-century after its formulation, it remains an unresolved problem whether and how the first stage of the modal model serves any useful function and how subsequent stages of the modal model receive inputs from the environment. Here, we propose a new conceptualization of human visual sensory memory by introducing an additional component whose reference-frame consists of motion-grouping based coordinates rather than retinotopic coordinates. We review data supporting this new model and discuss how it offers solutions to the paradoxes of the traditional model of sensory memory

Between Stillness and Motion

New technological media such as film, photography and computers have altered the way we perceive possible relations between stillness and motion in the visual arts. Traditionally, cinema theory saw cinema and especially the 'illusion of motion' as part of the ideological swindle of the basic cinematic apparatus. This collection of essays by acclaimed international scholars including Tom Gunning, Thomas Elsaesser, Mark B.N. Hansen, George Baker, Ina Blom and Christa Blümlinger, starts out from a different premise to analyse stillness and motion as part of a larger ecology of images and media. They argue that the strategic uses of stillness and motion in art and entertainment since the 1850s illuminate and renegotiate urgent issues within both aesthetics, film, art and media history on the one hand, and, on the other, new perspectives on affects, memories and the contemporary patterns of communication and image circulation

What Are the Visible and Invisible Archaeologies of Conflict in the Irish Landscape of Donegal and How May These Be Contextualised and Represented Through Arts Practice

The research question - What are the visible and invisible archaeologies of conflict in the Irish landscape of Donegal and how may these be contextualised and represented through arts practice? has been addressed through textual and historical research and through arts practice, using lens-based media in the exploration of an historic series of military circumstances, in the contemporary Irish landscape of County Donegal. The research undertaken and the resulting outcomes are presented as a textual narrative and as visual arts practice. The thesis material is composed of five chapters, each of which discusses selected arguments in the fields of, respectively; the modification of human sight through opticality and the emergence of modern photography, origins of the geographical discipline and the visual influence on formations of cultural landscape, a contemporary archaeological approach to sites of conflict and examples of relevant artwork, and a characterisation and discussion of Ireland\u27s position of neutrality during the Second World War, including a critical review of the images produced on this topic. This fourth chapter is intended to function as context and framework for the fifth chapter, the re-imagining of the landscape through the arts practice, shown in the Arc of Fire website, which is composed of selected visual material from the live research phase and the site-specific exhibition installed in Fort Dunree in the Inishowen peninsula. The conclusions form the final part of the thesis. Photography and lens based processes, explored as a critical history and employed as a working method of my professional arts practice, is fundamental to the research project

A Unified Cognitive Model of Visual Filling-In Based on an Emergic Network Architecture

The Emergic Cognitive Model (ECM) is a unified computational model of visual filling-in based on the Emergic Network architecture. The Emergic Network was designed to help realize systems undergoing continuous change. In this thesis, eight different filling-in phenomena are demonstrated under a regime of continuous eye movement (and under static eye conditions as well). ECM indirectly demonstrates the power of unification inherent with Emergic Networks when cognition is decomposed according to finer-grained functions supporting change. These can interact to raise additional emergent behaviours via cognitive re-use, hence the Emergic prefix throughout. Nevertheless, the model is robust and parameter free. Differential re-use occurs in the nature of model interaction with a particular testing paradigm. ECM has a novel decomposition due to the requirements of handling motion and of supporting unified modelling via finer functional grains. The breadth of phenomenal behaviour covered is largely to lend credence to our novel decomposition. The Emergic Network architecture is a hybrid between classical connectionism and classical computationalism that facilitates the construction of unified cognitive models. It helps cutting up of functionalism into finer-grains distributed over space (by harnessing massive recurrence) and over time (by harnessing continuous change), yet simplifies by using standard computer code to focus on the interaction of information flows. Thus while the structure of the network looks neurocentric, the dynamics are best understood in flowcentric terms. Surprisingly, dynamic system analysis (as usually understood) is not involved. An Emergic Network is engineered much like straightforward software or hardware systems that deal with continuously varying inputs. Ultimately, this thesis addresses the problem of reduction and induction over complex systems, and the Emergic Network architecture is merely a tool to assist in this epistemic endeavour. ECM is strictly a sensory model and apart from perception, yet it is informed by phenomenology. It addresses the attribution problem of how much of a phenomenon is best explained at a sensory level of analysis, rather than at a perceptual one. As the causal information flows are stable under eye movement, we hypothesize that they are the locus of consciousness, howsoever it is ultimately realized

Estimation du Temps à Collision en Vision Catadioptrique

Time to contact or time to collision (TTC) is of utmost importance information for animals as well as for mobile robots because it enables them to avoid obstacles; it is a convenient way to analyze the surrounding environment. The problem of TTC estimation is largely discussed in perspective images. Although a lot of works have shown the interest of omnidirectional camera for robotic applications such as localization, motion, monitoring, few works use omnidirectional images to compute the TTC. In this thesis, we show that TTC can be also estimated on catadioptric images. We present two approaches for TTC estimation using directly or indirectly the optical flow based on de-rotation strategy. The first, called ''gradient based TTC'', is simple, fast and it does not need an explicit estimation of the optical flow. Nevertheless, this method cannot provide a TTC on each pixel, valid only for para-catadioptric sensors and requires an initial segmentation of the obstacle.The second method, called ''TTC map estimation based on optical flow'', estimates TTC on each point on the image and provides the depth map of the environment for any obstacle in any direction and is valid for all central catadioptric sensors. Some results and comparisons in synthetic and real images will be given.Cette thèse s'intéresse à l'estimation du temps à collision d'un robot mobile muni d'une caméra catadioptrique. Ce type de caméra est très utile en robotique car il permet d'obtenir un champ de vue panoramique à chaque instant. Le temps de collision a été largement étudié dans le cas des caméras perspectives. Cependant, ces méthodes ne sont pas directement applicables et nécessitent d'être adaptées, à cause des distorsions des images obtenues par les caméras omnidirectionnelles. Dans ce travail, nous proposons d'exploiter explicitement et implicitement le flot optique calculé sur les images omnidirectionnelles pour en déduire le temps à collision (TTC) entre le robot et l'obstacle. Nous verrons que la double projection d'un point 3D sur le miroir puis sur le plan caméra aboutit à des nouvelles formulations du TTC pour les caméras catadioptriques. La première formulation est appelée globale basée sur les gradients, elle estime le TTC en exprimant le mouvement apparent en fonction du TTC et l'équation de la surface plane en fonction des coordonnées images et à partir des paramètres de son vecteur normal. Ces deux outils sont intégrés dans l'équation du flot optique (ECMA) afin d'en déduire le TTC. Cette méthode a l'avantage d'être simple rapide et fournit une information supplémentaire sur l'inclinaison de la surface plane. Néanmoins, la méthode globale basée sur les gradients est valable seulement pour les capteurs para-catadioptriques et elle peut être appliquée seulement pour les surfaces planes. La seconde formulation, appelée locale basée sur le flot optique, estime le TTC en utilisant explicitement le mouvement apparent. Cette formulation nous permet de connaître à chaque instant et sur chaque pixel de l'image le TTC à partir du flot optique en ce point. Le calcul du TTC en chaque pixel permet d'obtenir une carte des temps de collision. C'est une méthode plus générale car elle est valable pour tous les capteurs à PVU et elle peut être utilisée pour n'importe quelle forme géométrique d'obstacle. Les deux approches sont validées sur des données de synthèse et des expérimentations réelles

Vibrating Existence: Early Cinema and Cognitive Creativity

This thesis collects together technical, historical and neurological evidence to examine how our perceptual and cognitive experience of cinema has changed diachronically and especially as a result of the transition from analogue to digital cinema projection. The slow arrival but sudden dominance of digital projection technology has provided a historic opportunity of renewed interest in the means by which cinema is created. This research attends to a particular aspect of the experience of cinema which has failed to survive the industry-wide changeover: the seemingly advantageous deletion of the shutter and its attendant flicker from the cinematic dispositif – the ‘flicks’ are literally no more. The transdisciplinary approach employs a combination of historical film technological research, especially focussed on the Early Cinema period (1895-1915), experimental media archaeology, and empirical electrophysiological study, to investigate the cognitive impact of historical (flickering) and modern day (effectively flickerless) cinema technology. The research uncovers the prominence of the relation of the mechanical and the perceptual in the early cinema period and thickens our understanding of its texts and contexts, ultimately adding a new dimension to the substantial existing body of work on early cinema. The argument of the thesis is situated particularly in the sector of film archives and museums (Film Heritage Institutes) where recent work has concentrated on transferring films of the analogue era to data files for display on an all-pervasive network of digital screens. However, while digitisation may preserve the content of these films it does not preserve the experience. These digital copies speak only to traditional film histories based on literary or auteurist ideas and do not communicate the visceral sensory impact on the late nineteenth century viewer. It is suggested that through reinstating the connectedness of the mechanical and perceptual our understanding of early cinema experience can be transformed. The research also has further implications for other forms of moving image exhibition such as the continuing use of analogue film in artistic practice

Study on omnidirectional vision system using two reflecting mirrors and its applications

制度:新 ; 文部省報告番号:乙2148号 ; 学位の種類:博士(工学) ; 授与年月日:2008/2/25 ; 早大学位記番号:新471

Sistemas de comunicação e multimédia com integração de vídeo: evolução, situação actual e boas práticas

Mestrado em Gestão da InformaçãoA presente dissertação pretende reflectir a evolução, o papel, a aplicação e a integração de vídeo em sistemas de comunicação unidireccionais e bidireccionais. Versando fortemente o universo digital, o trabalho é composto pela contextualização do vídeo em cenários multimédia, o desenho de uma taxonomia vídeo (apresentando exemplos práticos para cada uma das categorias) e a avaliação de uma sessão de videoconferência. Para finalizar, são propostas boas práticas para a produção, integração e distribuição de vídeo em multimédia.The present work describes the progress, functions, application, and integration of video in unidireccional and bidirectional communication systems. Focusing mainly the digital domain, it addresses different matters, namely: (1) video contextualization in multimedia settings, (2) the framework for a video taxonomy, having covered examples for each case, (3) the evaluation of a videoconference session, and finally (4) the itemization of good practices for the production, integration and distribution of video in multimedia systems