PURPOSE. Gait during obstacle negotiation is adapted in visually normal subjects whose vision is temporarily and unilaterally blurred or occluded. This study was conducted to examine whether gait parameters in individuals with long-standing deficient stereopsis are similarly adapted. METHODS. Twelve visually normal subjects and 16 individuals with deficient stereopsis due to amblyopia and/or its associated conditions negotiated floor-based obstacles of different heights (7-22 cm). Trials were conducted during binocular viewing and monocular occlusion. Analyses focused on foot placement before the obstacle and toe clearance over it. RESULTS. Across all viewing conditions, there were significant group-by-obstacle height interactions for toe clearance (P < 0.001), walking velocity (P = 0.003), and penultimate step length (P = 0.022). Toe clearance decreased (similar to 0.7 cm) with increasing obstacle height in visually normal subjects, but it increased (similar to 1.5 cm) with increasing obstacle height in the stereo-deficient group. Walking velocity and penultimate step length decreased with increasing obstacle height in both groups, but the reduction was more pronounced in stereo-deficient individuals. Post hoc analyses indicated group differences in toe clearance and penultimate step length when negotiating the highest obstacle (P < 0.05). CONCLUSIONS. Occlusion of either eye caused significant and similar gait changes in both groups, suggesting that in stereo-deficient individuals, as in visually normal subjects, both eyes contribute usefully to the execution of adaptive gait. Under monocular and binocular viewing, obstacle-crossing performance in stereo-deficient individuals was more cautious when compared with that of visually normal subjects, but this difference became evident only when the subjects were negotiating higher obstacles; suggesting that such individuals may be at greater risk of tripping or falling during everyday locomotion. / RCUK (Research Councils, UK)

O estudo teve como objetivos verificar em dois grupos de pacientes com visão monocular (grupo 1) e com visão binocular (grupo 2), a serem submetidos à cirurgia de catarata no Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, opiniões, expectativas e reações emocionais em relação ao problema ocular, à qualidade da visão e à cirurgia de catarata; influência da característica de apresentar visão mono ou binocular nas reações emocionais relacionadas à cirurgia de catarata. Foi realizado estudo transversal e comparativo, de forma consecutiva, por meio de questionário estruturado, aplicado por entrevista a pacientes, elaborado a partir de estudo exploratório e medidas acuidade visual e causa da perda visual. A amostra foi constituída por 96 indivíduos do grupo 1 (50,0% homens; 50,0% mulheres, com idade entre 41 e 91 anos, média 69,3 anos ± 10,4 anos) e 110, do grupo 2 (40,9% homens; 59,1% mulheres, com idade entre 40 e 89 anos, média 68,2 anos ± 10,2 anos). A maioria dos indivíduos de ambos os grupos apresentava baixa escolaridade. Não houve diferença estatisticamente significante entre os grupos em relação ao sexo (p = 0,191), à idade (p = 0,702) e à escolaridade (p = 0,245). Não exerciam atividade laboral 95,8% dos indivíduos do grupo 1 e 83,6%, do grupo 2 (p = 0,005) e 30,4% do grupo 1 mencionaram não ter possibilidade de trabalhar por causa da deficiência visual. Observou-se acuidade visual do olho a ser operado menor que 0,05 em 40,6% (grupo 1) e 33,6% (grupo 2), entre 0,25 e 0,05. Quase a totalidade dos indivíduos de ambos os grupos afirmou ter dificuldade para realização das atividades de vida diária e qualificou como insuficiente a respectiva acuidade visual; 71,9% dos entrevistados do grupo 1 e 71,6%, do grupo 2 mencionaram saber a causa da visão fraca; desses, 87,1% do grupo 1 e 83,3% do grupo 2 referiram a catarata como causa da baixa acuidade visual. No que se refere ao medo, 40,6% dos indivíduos do grupo 1 e 22,7%, do grupo 2, relataram ter medo do procedimento cirúrgico (p = 0,009). As causas de medo mais referidas foram: possibilidade de perder a visão; piorar a visão; sofrer alguma complicação na cirurgia; morrer durante a cirurgia. Os sentimentos mais preponderantes entre os grupos foram: satisfação por saber que a catarata pode ser operada e melhorar a visão, alívio por saber que vai ser operado, dúvida quanto a ter bom resultado, nervosismo. Referiram esperar que mudanças ocorressem na vida após a cirurgia 90,6% (grupo 1) e 84,6% (grupo 2). Quanto às atividades que esperavam realizar após a cirurgia mencionaram: realizar serviços de casa; ler; sair sozinho. Concluiu-se que: os indivíduos de ambos os grupos tiveram acesso à cirurgia de catarata com acuidade visual menor do que a idealmente indicada; os pacientes com visão monocular apresentaram acuidade visual significativamente menor em relação aos com visão binocular; a maioria dos entrevistados de ambos os grupos referiu dificuldades para realizar atividades cotidianas como conseqüência da baixa visão; os indivíduos com visão monocular referiram mais dúvida em relação aos resultados cirúrgicos do que os com visão binocular; muitos indivíduos de ambos os grupos desconheciam a causa da dificuldade visual ou a atribuíram a outra causa que não a catarata; indivíduos de ambos os grupos apontaram expectativas positivas em relação à reabilitação após a cirurgia. / The purpose of the study was to verify in two groups of patients with monocular vision (group 1) and with binocular vision (group 2) to be submitted to cataract surgery in Hospital das Clínicas, São Paulo University Medical School, opinions, expectances and emotional reactions related to the ocular problem, to the quality of vision and to cataract surgery, the influence of monocular or binocular vision in the emotional reactions related to cataract surgery. A transversal comparative and consecutive study was performed using a structured questionnaire applied by interview of patients. The questionnaire was elaborated from a previous exploratory study, the visual acuity and cause of the visual loss were evaluated. The sample was constituted by 96 persons of group 1 (50% males; 50% females, ages ranging from 41 to 91 years old; average 69,3 years ± 10,4 years) and 110 persons of group 2 (40,9% males; 59,1% females, ages ranging from 40 to 89 years old; average 68,2 years ± 10,2 years). The majority of persons of both groups presented low educational level. There was no statistically significant difference between the groups in relation to gender (p = 0,191), age (p = 0,702) and educational level (p = 0,245). No work activity was mentioned in 95,8% of the persons of group 1 and 83,6% of group 2 (p = 0,005) and 30,4% of group 1 informed the impossibility to work due the visual deficiency. It was observed that the visual acuity of the eye to be operated was less than 0,05 in 40,6% (group 1) and in 33,6% (group 2), presented visual acuity ranging from 0,05 to 0,25. Almost the totality of the persons of both groups informed difficulties to perform activities of daily life and qualified as insufficient their visual acuities; 71,9% of the patients of group 1 and 71,6% of group 2 informed to know the reason of low vision; among these, 87,1% of group 1 and 83,3% of group 2 mentioned cataract as the reason of low visual acuity. Concerning fear, 40,6% of patients of group 1 and 22,7% of group 2 informed about fear of the surgical procedure (p = 0,009). The causes of fear more frequently reported were: possibility of loss of vision; worsening of vision; complications during the surgical procedure and to die during the surgery. The more preponderant feelings in both groups were: satisfaction knowing that a cataract can be operated with improvement of vision, relief knowing that will be submitted to surgery, doubt about a good result, nervousness. Changes in the life after surgery were mentioned by 90,6% (group 1) and by 84,6% (group 2) of the persons. Housework activities, reading and moving around without help were the mentioned activities expected to be performed after surgery. It was concluded that the patients of both groups were submitted to cataract surgery with visual acuities less than the visual acuity ideally indicated; the patients with monocular vision showed visual acuities significantly less in relation to the patients with binocular vision; the majority of the patients of both groups mentioned difficulties to perform daily activities as a consequence of low vision; patients with monocular vision mentioned doubts in relation to the surgical results as compared with the patients with binocular vision; many patients of both groups did not know the cause of the visual difficulty or explained the visual difficulty by other cause than the cataract; patients of both groups were positively expectant in relation to the visual rehabilitation after the surgery.

Conformal geometric algebra is defined in the thesis. Representations of geometric objects and possibilities of their geometric transformations are presented. Conformal geometric algebra is applied to the calculation of forward kinematics of a robotic manipulator UR10 from Universal Robots. It is also applied to determine the position of the machine based on the location and rotation of two cameras. Then it is used in an inverse task, where based on records from the two cameras, dimensions of the UR10 manipulator and possibilities of its movement, the mutual position of these cameras is determined. And consequently the possibilities of their location in space. Finally, the derived procedures are implemented in a custom program created in the CluCalc environment, using which a sample example verifying the correctness of these procedures is calculated.

In this work I have been briefed by physiology of binocular vision for acquisition of three-dimensional perception from two-dimensional images using special glasses. At first I described optical organ, after it I described physiology of binocular vision. In the next part of my work I described stereoscopic imaging technology and their advantages and disadvantages. In the next part of this work I have designed method for measuring ideal distance between cameras for scanning and projection of stereoscopic image using program Inition StereoBrain Calculator. After scenes design I have collected visual data for creating 3D videos. This videos were been projected to the group of the viewers. Data from the viewers were been analyzed afterwards.

No description available.

No / Epidemiologic research has shown that multifocal spectacle wearers (bifocal and progressive addition lenses [PALs]) are more than twice as likely to fall than are nonmultifocal spectacle wearers, with this risk further increasing when negotiating stairs. The present study investigated whether step and stair descent safety is improved by using single-vision distance lenses. METHODS: From a stationary standing position on top of a block, 20 long-term multifocal wearers stepped down (from different block heights) onto a lower level wearing bifocal, progressive addition, or single-vision distance lenses. RESULTS: Use of single-vision distance spectacles led to an increased single-limb support time, a reduced ankle and knee angle and vertical center-of-mass velocity at contact with the lower level, and a reduced ankle angular velocity and vertical center-of-mass velocity during initial landing (P < 0.03). These findings indicate that landing occurred in a more controlled manner when the subjects wore single-vision distance spectacles, rather than tending to "drop" onto the lower level as occurred when wearing bifocals or PALs. CONCLUSIONS: Use of single-vision distance spectacles led to improvements in landing control, consistent with individuals' being more certain regarding the precise height of the lower floor level. This enhanced control was attributed to having a view of the foot, step edge, and immediate floor area that was not blurred, magnified, or doubled and that did not suffer from image jump or peripheral distortions. These findings provide further evidence that use of single-vision distance lenses in everyday locomotion may be advantageous for elderly multifocal wearers who have a high risk of falling.

No / To determine the test-retest reliability of the Randot stereoacuity test when used as part of vision screening in schools. METHODS: Randot stereoacuity (graded-circles) and logMAR visual acuity measures were gathered in an unselected sample of 139 children (aged 4-12, mean 8.1+/-2.1 years) in two schools. Randot testing was repeated on two occasions (average interval between successive tests 8 days, range: 1-21 days). Three Randot scores were obtained in 97.8% of children. RESULTS: Randot stereoacuity improved by an average of one plate (ie, one test level) on repeat testing but was little changed when tested on the third occasion. Within-subject variability was up to three test levels on repeat testing. When stereoacuity was categorised as 'fine', 'intermediate' or 'coarse', the greatest variability was found among younger children who exhibited 'intermediate' or 'coarse'/nil stereopsis on initial testing. Whereas 90.8% of children with 'fine' stereopsis (</=50 arc-seconds) on the first test exhibited 'fine' stereopsis on both subsequent tests, only approximately 16% of children with 'intermediate' (>50 but </=140 arc-seconds) or 'coarse'/nil (>/=200 arc-seconds) stereoacuity on initial testing exhibited stable test results on repeat testing. CONCLUSIONS: Children exhibiting abnormal stereoacuity on initial testing are very likely to exhibit a normal result when retested. The value of a single, abnormal Randot graded-circles stereoacuity measure from school screening is therefore questionable.

This thesis analyzes the problem of acquiring stereoscopic images in all gazing directions around a reference viewpoint in space with the purpose of creating stereoscopic panoramas of non-static scenes. The generation of immersive stereoscopic imagery suitable to stimulate human stereopsis requires images from two distinct viewpoints with horizontal parallax in all gazing directions, or to be able to simulate this situation in the generated imagery. The available techniques to produce omnistereoscopic imagery for human viewing are not suitable to capture dynamic scenes stereoscopically. This is a not trivial problem when considering acquiring the entire scene at once while avoiding self-occlusion between multiple cameras. In this thesis, the term omnidirectional refers to all possible gazing directions in azimuth and a limited set of directions in elevation. The acquisition of dynamic scenes restricts the problem to those techniques suitable for collecting in one simultaneous exposure all the necessary visual information to recreate stereoscopic imagery in arbitrary gazing directions. The analysis of the problem starts by defining an omnistereoscopic viewing model for the physical magnitude to be measured by a panoramic image sensor intended to produce stereoscopic imagery for human viewing. Based on this model, a novel acquisition model is proposed, which is suitable to describe the omnistereoscopic techniques based on horizontal stereo. From this acquisition model, an acquisition method based on multiple cameras combined with the rendering by mosaicking of partially overlapped stereoscopic images is identified as a good candidate to produce omnistereoscopic imagery of dynamic scenes. Experimental acquisition and rendering tests were performed for different multiple-camera configurations. Furthermore, a mosaicking criterion between partially overlapped stereoscopic images based on the continuity of the perceived depth and the prediction of the location and magnitude of unwanted vertical disparities in the final stereoscopic panorama are two main contributions of this thesis. In addition, two novel omnistereoscopic acquisition and rendering techniques were introduced. The main contributions to this field are to propose a general model for the acquisition of omnistereoscopic imagery, to devise novel methods to produce omnistereoscopic imagery, and more importantly, to contribute to the awareness of the problem of acquiring dynamic scenes within the scope of omnistereoscopic research.

This thesis analyzes the problem of acquiring stereoscopic images in all gazing directions around a reference viewpoint in space with the purpose of creating stereoscopic panoramas of non-static scenes. The generation of immersive stereoscopic imagery suitable to stimulate human stereopsis requires images from two distinct viewpoints with horizontal parallax in all gazing directions, or to be able to simulate this situation in the generated imagery. The available techniques to produce omnistereoscopic imagery for human viewing are not suitable to capture dynamic scenes stereoscopically. This is a not trivial problem when considering acquiring the entire scene at once while avoiding self-occlusion between multiple cameras. In this thesis, the term omnidirectional refers to all possible gazing directions in azimuth and a limited set of directions in elevation. The acquisition of dynamic scenes restricts the problem to those techniques suitable for collecting in one simultaneous exposure all the necessary visual information to recreate stereoscopic imagery in arbitrary gazing directions. The analysis of the problem starts by defining an omnistereoscopic viewing model for the physical magnitude to be measured by a panoramic image sensor intended to produce stereoscopic imagery for human viewing. Based on this model, a novel acquisition model is proposed, which is suitable to describe the omnistereoscopic techniques based on horizontal stereo. From this acquisition model, an acquisition method based on multiple cameras combined with the rendering by mosaicking of partially overlapped stereoscopic images is identified as a good candidate to produce omnistereoscopic imagery of dynamic scenes. Experimental acquisition and rendering tests were performed for different multiple-camera configurations. Furthermore, a mosaicking criterion between partially overlapped stereoscopic images based on the continuity of the perceived depth and the prediction of the location and magnitude of unwanted vertical disparities in the final stereoscopic panorama are two main contributions of this thesis. In addition, two novel omnistereoscopic acquisition and rendering techniques were introduced. The main contributions to this field are to propose a general model for the acquisition of omnistereoscopic imagery, to devise novel methods to produce omnistereoscopic imagery, and more importantly, to contribute to the awareness of the problem of acquiring dynamic scenes within the scope of omnistereoscopic research.

D.Ed. / Stereopsis -- binocular depth perception is a visual function which falls within the ambit of the hyperacuities. The term, Hyperacuity, is one coined by Westheimer (1976) to describe thresholds of discrimination which cannot be explained on the basis of the optical components or sensory elements of the eyes alone. By implication such levels of discrimination are effected by higher levels of brain function. It is reasoned that an individual's stereoscopic hyperacuity should in some way relate to other measures of higher sensory and motor brain functions. In a school situation hyperacuity should relate to measures of intelligence, as well as scholastic and sporting achievement. The design and implementation of an experiment to test this premise forms the basis of this thesis. A literature review is reported of current knowledge relevant to this study together with a description of the stereoscopic testing instruments commonly available in clinical practice. A rationale for modifying these instruments and testing methods to suit the needs of this study is also included. This study exposes new knowledge about the process of static nearpoint stereopsis. This stereopsis proves to be a complex of diverse skills, which are significantly age-related and developmental in nature. These skills are seen to influence and be influenced by educational interventions. It may be concluded from this study that there is value in measuring stereopsis in more depth than has been done previously and that it is crucial to measure the speed of stereo performance in its own right in addition to the measures of stereoacuity. The study reveals significant differences of performance which relate to stereopsis in front as opposed to behind the plane of regard and also related to figure/ground contrast differences. The two non-stereoscopic tests and the six different stereoscopic tests described in this thesis prove to be highly discriminative and diagnostic with respect to age, grade level, I.Q., scholastic achievement and sporting ability.