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Binocular camera fixation refers to the control of camera movements so that the optical axes of two cameras converge at a single point of interest in a three-dimensional scene. This thesis describes the theory and high-level algorithms for a procedure that can locate fixation points in an image pair. The binocular fixation procedure which has been developed here combats several difficult fixation problems that are hard to overcome with traditional approaches. Examples of this are objects lacking in visual texture, scenes with occluding conditions, repeating patterns, and objects which are steeply slanted with respect to the image planes. In order to deal with low-contrast image regions, the system is capable of detecting nearby salient points and shifting attention to a new salient target. Based on local image information, the system adaptively determines an initial window size using an Autoregressive-Moving Average (ARMA) modeling technique. Area-based feature matching is performed using normalized cross-covariance within a multiresolution image hierarchy. Gaussian low-pass filters of increasing spatial resolution are used to construct the hierarchy, and matching is performed in coarse-to-fine order. Finally, affine image warping is used in some cases to reduce the effects of perspective distortion so that area based image comparison is improved. The method presented here can serve as the foundation of a stereo tracking system, and has potential applications in such areas as autonomous vehicle navigation, industrial process control, and visually guided robot manipulation. / Master of Science

Yes / Binocularity in the human visual system poses two interesting and extremely challenging questions. The first, and perhaps most obvious stems from the singularity of perception even though the neural images we see originate as two separate images in the right and left eyes. Mechanistically we can ask how and where do we convert two images into one? The second question is more of a “why” question. By converting lateral eyes with their inherent panoramic visual field into frontal eyes with overlapping binocular visual fields, primates have developed an extremely large blind region (the half of the world behind us). We generally accept that this sacrifice in visual field size was driven by the potential benefit of extracting information about the 3rd dimension from overlapping right and left eye visual fields. For some people, both of these core processes of binocularity fail: a single fused binocular image is not achieved (when diplopia or suppression is present), and the ability to accurately represent the 3rd dimension is lost (stereo-blindness). In addition to these failures in the core functions of the human binocular system, early imbalances in the quality of right and left eye neural images (e.g. due to anisometropia, monocular deprivation, and/or strabismus), can precipitate profound neurological changes at a cortical level which can lead to serious vision loss in one eye (amblyopia). Caring for patients with malfunctioning binocular visual systems is a core therapeutic responsibility of the eye care professions (optometry, ophthalmology and orthoptics) and significant advances in patient care and subsequent visual outcomes will be gained from a deeper understanding of how the human brain accomplishes full binocular integration. This feature issue on binocular vision brings together original articles and reviews from leading groups of neuroscientists, psychophysicists and clinical scientists from around the world who embrace the multidisciplinary nature of this topic. Our authors have taken on the big issues facing the research community tasked with understanding how binocular vision is meant to work, how it fails, and how to better treat those with compromised binocularity. These studies address deep issues about how the human brain functions and how it fails, as well as how it can be altered by therapy.

Yes / We have read with interest the recent article by Sponsel et al.1 There is much evidence that glaucomatous damage occurs at the optic nerve head,2 and therefore we were surprised by the authors' conjecture that there may be a central mechanism that preserves the binocular visual field in advanced glaucoma.

The main aim of this thesis was to evaluate the performance of the contrast sensitivity clock (CSC), a new screening device for measuring contrast sensitivity (CS) and glare. This device allows CS without glare, with glare and disability glare scores to be recorded. After initial data collection the design of the CSC was slightly amended improving the performance of the device. The amended design of the CSC was shown to be a valid, discriminative and repeatable measure for purpose. The CSC is also a quick test to perform and is relatively cheap to produce. If all these factors are considered it shows potential to become the test of choice for the assessment of visual glare. A head-mounted display system was also evaluated in terms of the glare effects it may cause. The monocular display screen of the device significantly reduced the CS of the eye directly exposed but also had an effect on binocular performance, reducing amounts of binocular summation. Electronic devices, including head-mounted displays and satellite navigation systems can seriously affect CS at low luminance levels, similar to those found when driving at night.

Orientador: Clésio Luis Tozzi / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-20T02:20:27Z (GMT). No. of bitstreams: 1 Gomes_MarceloMarques_M.pdf: 2920969 bytes, checksum: 0ae0c041b47241b92c32e9792f18d608 (MD5) Previous issue date: 2012 / Resumo: Este trabalho aborda a solução para o problema da recuperação da informação tridimensional somente a partir de imagens da cena ou do objeto que se deseja modelar desconhecidas as informações a respeito das câmeras utilizadas. A solução apresentada divide-se em duas partes: na primeira se estabelece a relação entre pares ou trios de câmeras utilizando matriz fundamental ou tensor trifocal, respectivamente e a partir dessas relações obtém-se por meio de triangulação uma reconstrução tridimensional da cena ou do objeto observado em função de uma transformação projetiva arbitrária. Na segunda parte determina-se uma transformação que leva a cena ou o objeto obtidos no espaço projetivo para o espaço métrico. Essa transformação que leva o objeto recuperado no espaço projetivo para o espaço métrico é encontrada por meio de autocalibração utilizando o plano no infinito e a cônica absoluta que apresentam a propriedade de serem invariantes a rotação, translação e escala, em relação a um referencial escolhido arbitrariamente. Dependendo do número de imagens disponíveis é necessário inserir restrições nos parâmetros intrínsecos das câmeras para viabilizar o cálculo da transformação. Essas restrições são inseridas na forma de suposições a respeito dos parâmetros intrínsecos das câmeras, como pontos principais conhecidos ou constantes entre as câmeras, skew nulo, relação de aspecto unitária etc. Os resultados da reconstrução no espaço projetivo obtidos com o uso da matriz fundamental e do tensor trifocal foram comparados em relação ao erro de reconstrução utilizando protótipo implementado em Matlab e imagens sintéticas. A solução geral foi avaliada em relação ao erro de reprojeção, reconstrução no espaço métrico com base em imagens sintéticas e imagens reais de objetos conhecidos, utilizando um protótipo desenvolvido na plataforma Embarcadero Delphi / Abstract: This work addresses a solution to the problem of recovering three-dimensional information from images of a scene or modeled object based only on images and without any information of the cameras parameters. The presented solution is divided in two parts: in the first part it is established the relationship between a pair or a triple of cameras using the fundamental matrix or trifocal tensor, respectively, and obtained by triangulation a three-dimensional reconstruction of the observed scene or object in function of an arbitrary projective transformation. In the second part it is determined a transformation to covert the obtained scene or object reconstruction from the projective space to the metric space. This transformation is found by auto-calibration using the plane at infinity and the absolute conic which have the property of being invariant to rotation, translation and scale in relation to an arbitrarily chosen reference frame. According to the number of available images, restrictions on the intrinsic parameters may be necessary in order to obtain a valid transformation. These restrictions are inserted in the form of assumptions about the values of the intrinsic parameters of the cameras or relations between then, like known principal points or constant values for the cameras, zero skew, unit aspect ratio and so on. Using synthetic images and a prototype implemented in Matlab, the results of reconstruction in projective space based on the fundamental matrix and trifocal tensor were compared in relation to the error of reconstruction. Based on synthetic images and real images of known objects and a prototype developed in the Embarcadero Delphi platform, the general solution was evaluated in relation to the reprojection error and the error of reconstruction in the metric space / Mestrado / Engenharia de Computação / Mestre em Engenharia Elétrica

The main aim of this thesis was to evaluate the performance of the contrast sensitivity clock (CSC), a new screening device for measuring contrast sensitivity (CS) and glare. This device allows CS without glare, with glare and disability glare scores to be recorded. After initial data collection the design of the CSC was slightly amended improving the performance of the device. The amended design of the CSC was shown to be a valid, discriminative and repeatable measure for purpose. The CSC is also a quick test to perform and is relatively cheap to produce. If all these factors are considered it shows potential to become the test of choice for the assessment of visual glare. A head-mounted display system was also evaluated in terms of the glare effects it may cause. The monocular display screen of the device significantly reduced the CS of the eye directly exposed but also had an effect on binocular performance, reducing amounts of binocular summation. Electronic devices, including head-mounted displays and satellite navigation systems can seriously affect CS at low luminance levels, similar to those found when driving at night.

This thesis investigates the use of binocular information for motion-in-depth (MID) perception. There are at least two different types of binocular information available to the visual system from which to derive a perception of MID: changing disparity (CD) and inter-ocular velocity differences (IOVD). In the following experiments, we manipulate the availability of CD and IOVD information in order to assess the relative influence of each on MID judgements. In the first experiment, we assessed the relative effectiveness of CD and IOVD information for MID detection, and whether the two types of binocular information are processed by separate mechanisms with differing characteristics. Our results suggest that, both CD and IOVD information can be utilised for MID detection, yet, the relative dependence on either of these types of MID information varies between observers. We then went on to explore the contribution of CD and IOVD information to time-to-contact (TTC) perception, whereby an observer judges the time at which an approaching stimulus will contact them. We confirmed that the addition of congruent binocular information to looming stimuli can influence TTC judgements, but that there is no influence from binocular information indicating no motion. Further to this, we found that observers could utilise both CD and IOVD for TTC judgements, although once again, individual receptiveness to CD and/or IOVD information varied. Thus, we demonstrate that the human visual system is able to process both CD and IOVD information, but the influence of either (or both) of these cues on an individual’s perception has been shown to be mutually independent.

[pt] As comunicações à distância estão crescendo consideravelmente pelo uso de aplicações através da Internet e de ambientes virtuais. Interaçõoes sociais e pessoais têm recebido especial enfoque, sobretudo a videoconferência, acarretando uma grande demanda de tecnologia apropriada para esses sistemas. Resultados de pesquisas em Presença, alguns deles obtidos nesta tese, permitiram inferir os quatro pilares da proposta: 1. visualização é muito importante nas interações sociais/pessoais; 2. tecnologia simples pode promover presença social; 3. imagens de câmera são mais satisfatórias do que avatares para algumas interações sociais/pessoais; 4. estereoscopia influência presença positivamente. Sob a restrição de usar tecnologia simples e de baixo custo, a tese propõe o uso de visualização estereoscópica para webcams, em tempo real. Porque webcams são equipamentos simples com baixa resolução de imagem, a obtenção de um estéreo com qualidade torna- se um desafio. Partindo do princípio que o olho humano não se comporta da mesma forma para ver de perto e de longe, a pesquisa analisou o processamento de estéreo natural do olho humano, e com base em resultados psicofísicos e fisiológicos da visão binocular, a tese propõe um modelo para o processamento de imagens estereoscópicas a serem visualizadas em curta distância, e usa este modelo na implementação apresentada. Os resultados obtidos foram satisfatórios para a visualização de imagens estéreo com webcams, em tempo real, e principalmente, eliminaram a necessidade de reajuste de paralaxe das imagens e do reposicionamento das câmeras a cada movimentação do observador, dando assim mais liberdade de visualização ao observador. / [en] The improvement of communication among remotely located people constitutes a very comprehensive prominent subject nowadays. Among applications to attain this goal, some aim to support social and personal interactions to meet partners, friends and family in distance. Presence research results, some obtained as part of this thesis, allowed to infer the four pillars of the proposal: 1. visualization is very important in social/personal interactions, mainly when people have close social/personal relationship; 2. simple technology can afford social presence; 3. camera images are more satisfactory than avatars during some social/personal interactions; 4. stereoscopy influences presence positively. Under the constraint of using simple technology without adding any special hardware to a PC system, the thesis proposes the use of stereoscopy through webcams, in real- time, as one solution to add 3D features to camera images. Since webcams are simple equipments with low resolution, to obtain stereo images in good quality is a challenge. Considering the fact that human eyes treat short and long distance in a different way, this research analysed the natural stereo processing of human eye, and based on psychophysical and physiological features of binocular vision, the thesis proposes a model to process stereoscopic images to be visualized in short distance, and implemented it as a proof of concept. The obtained results are satisfactory for stereoscopic images visualization through webcams, in real-time, and mainly, eliminated the need of adjusting images parallax and cameras position for each viewer´s movement, allowing more freedom to the viewer.