This thesis involves systems for virtual presence in remote locations, a field referred to as telepresence. Recent image-based representations such as Google map's street view provide a familiar example. Several areas of research are open; such image-based representations are huge in size and the necessity to compress data efficiently for storage is inevitable. On the other hand, users are usually located in remote areas, and thus efficient transmission of the visual information is another issue of great importance. In this work, real-world images are used in preference to computer graphics representations, mainly due to the photorealism that they provide as well as to avoid the high computational cost required for simulating large-scale environments. The cubic format is selected for panoramas in this thesis. A major feature of the captured cubic-panoramic image datasets in this work is the assumption of static scenes, and major issues of the system are compression efficiency and random access for storage, as well as computational complexity for transmission upon remote users' requests. First, in order to enable smooth navigation across different view-points, a method for aligning cubic-panorama image datasets by using the geometry of the scene is proposed and tested. Feature detection and camera calibration are incorporated and unlike the existing method, which is limited to a pair of panoramas, our approach is applicable to datasets with a large number of panoramic images, with no need for extra numerical estimation. Second, the problem of cubic-panorama image dataset compression is addressed in a number of ways. Two state-of-the-art approaches, namely the standardized scheme of H.264 and a wavelet-based codec named Dirac, are used and compared for the application of virtual navigation in image based representations of real world environments. Different frame prediction structures and group of pictures lengths are investigated and compared for this new type of visual data. At this stage, based on the obtained results, an efficient prediction structure and bitstream syntax using features of the data as well as satisfying major requirements of the system are proposed. Third, we have proposed novel methods to address the important issue of disparity estimation. A client-server based scheme is assumed and a remote user is assumed to seek information at each navigation step. Considering the compression stage, a fast method that uses our previous work on the geometry of the scene as well as the proposed prediction structure together with the cubic format of panoramas is used to estimate disparity vectors efficiently. Considering the transmission stage, a new transcoding scheme is introduced and a number of different frame-format conversion scenarios are addressed towards the goal of free navigation. Different types of navigation scenarios including forward or backward navigation, as well as user pan, tilt, and zoom are addressed. In all the aforementioned cases, results are compared both visually through error images and videos as well as using the objective measures. Altogether free navigation within the captured panoramic image datasets will be facilitated using our work and it can be incorporated in state-of-the-art of emerging cubic-panorama image dataset compression/transmission schemes.

The technology of haptics rendering has greatly enriched development in Multimedia applications, such as teleoperation, gaming, medical and etc., because it makes the virtual object touchable by the human operator(s) in real world. Human head stiffness rendering is significant in haptic interactive applications as it defines the degree of reality in physical interaction of a human avatar created in virtual environment. In a similar research, the haptic rendering approach has two main types: 1) Haptic Information Integration and 2) Deformation Simulation. However, the complexity in anatomic and geometric structure of a human head makes the rendering procedure challenging because of the issues of accuracy and efficiency. In this work, we propose a hybrid method to render the appropriate stiffness property onto a 3D head polygon mesh of an individual user by firstly studying human head's sophisticated deformation behaviour and then rendering such behaviour as the resultant stiffness property on the polygon mesh. The stiffness property is estimated from a semantically registered and shape-adapted skull template mesh as a reference and modeled from soft tissue's deformation behaviour in a nonlinear Finite Element Method (FEM) framework. To render the stiffness property, our method consists of different procedures, including 3D facial landmark detection, models semantic registration using Iterative Closest Point (ICP) technique, adaptive shape modification processed with a modified Weighted Free-Form Deformation (FFD) and FEM Simulation. After the stiffness property is rendered on a head polygon mesh, we perform a user study by inviting participants to experience the haptic feedback rendered from our results. According to the participants' feedback, the head polygon mesh's stiffness property is properly rendered as it satisfies their expectation.

Land use regulations are typically established as a response to development activity. For effective growth management and habitat preservation, the opposite should occur. This study considers tree preservation ordinances of the Dallas-Fort Worth metropolitan area as a means of evaluating development regulation in a metropolitan context. It documents the impact urban cores have on regulations and policies throughout their region, demonstrating that the same urban-rural gradient used to describe physical components of our metropolitan areas also holds true in terms of policy formation. Although sophistication of land use regulation generally dissipates as one moves away from an urban core, native habitat is more pristine at the outer edges. To more effectively protect native habitat, regional preservation measures are recommended.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-01-20T14:02:39Z No. of bitstreams: 1 lucianalimagentilribeiro.pdf: 5045937 bytes, checksum: 338891e62a317ed04639084d01446292 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-01-25T18:37:01Z (GMT) No. of bitstreams: 1 lucianalimagentilribeiro.pdf: 5045937 bytes, checksum: 338891e62a317ed04639084d01446292 (MD5) / Made available in DSpace on 2016-01-25T18:37:01Z (GMT). No. of bitstreams: 1 lucianalimagentilribeiro.pdf: 5045937 bytes, checksum: 338891e62a317ed04639084d01446292 (MD5) Previous issue date: 2014-08-13 / O presente trabalho busca identificar as dificuldades e os desafios frequentes apontados pelos gestores como possíveis obstáculos para a autuação dos processos de prestação de contas dos recursos estaduais, de merenda e de manutenção, e que podem acabar sendo fator determinante da causa da inadimplência da Unidade Escolar. Ainda que, a Resolução SEEDUC nº 3630/2007 oriente quanto ao dispositivo de como elaborar a prestação de contas e de que maneira os recursos podem ser executados, alguns gestores apresentam dificuldades em cumprir, dentro do prazo determinado, o que lhe é confiado e exigido. Para a coleta dos dados, foi aplicado um questionário aos gestores das UEs localizadas em quatro municípios do Estado do Rio de Janeiro, a saber, Belford Roxo, Mesquita, Nilópolis e São João de Meriti, que fazem parte da Regional Metropolitana VII. Este trabalho foi elaborado a partir de um estudo de caso, a metodologia utilizada foi qualitativa, e, como principal aporte teórico utilizou-se os estudos de Heloísa Lück. Os dados coletados apontaram para três principais dificuldades de acordo com a percepção dos gestores respondentes: carência de pessoal, dificuldade em cumprir os prazos determinados pela SEEDUC/RJ e falta de tempo para se dedicar à prestação de contas. A partir dos resultados, apresenta-se um Plano de Ação cujas proposições sugerem ações palpáveis que contribuam positivamente para que o gestor possa cumprir com as exigências da Secretaria de Educação, evitando possíveis punições em decorrência do não cumprimento dos prazos. Tais proposições estão voltadas para a capacitação dos gestores, compartilhamento de experiências, busca de soluções em grupo para os obstáculos apresentados e auxilio para dirimir as dificuldades ainda apresentadas por esses gestores. / This work aims to identify difficulties and challenges which are frequently pointed out by managers as possible hindrances to the filing of the proceedings of account rendering of state resources for school meals and maintenance, and which can be determining factors of the cause of default by school units. Even though the Resolution of SEEDUC (State Department of Education of Rio de Janeiro) number 3630/2007 provides guidance as to the provision on how to render accounting and in what manner resources can be executed, some managers face difficulties in fulfilling within due time what is expected and demanded from them. In this dissertation, in order to collect data, a questionnaire was submitted to managers of school units located in four towns of the state of Rio de Janeiro: Belford Roxo, Mesquita, Nilópolis and São João de Meriti, which are part of Regional Metropolitana VII (Metropolitan Region VII). This work was developed from a case study; its methodology was of a qualitative character, since it aimed to find the main challenges of school managers related to account rendering. As its main theoretic sources, studies by Heloísa Lück, as well as authors Martins, Libâneo and Polon, were considered. Data collected pointed to three main difficulties, according to the perceptions of answering managers: shortage of staffs, difficulties in meeting deadlines set by SEEDUC/RJ and lack of time to put into account rendering. From these results, a Plan of Action is presented, whose propositions suggest solid actions that might contribute substantially so that a manager can fulfill the demands of the Department of Education, preventing possible consequences of not meeting deadlines, such as answering to account taking. The propositions presented in this work are aimed at qualifying managers, sharing experiences, seeking group solutions for hindrances that are presented and assistance to prevent difficulties faced by those managers.

This thesis explores the balance between visual quality and the performance of a 3D object for computer games. Additionally, it aims to help new 3D artists to create assets that are both visually adequate and optimized for real-time rendering. It further investigates the differences in the judgement of the visual quality of thosethat know computer graphics, and thosenot familiar with it. Many explanations of 3D art optimization are often highly technical and challenging for graphic artists to grasp. Additionally, they regularly neglect the effects of optimization to the visual quality of the assets. By testing several 3D assets to measure their render time while using a survey to gather their visual assessments, it was discovered that 3D game art is very contextual. No definite or straightforward way was identified to find the balance between art quality and performance universally. Neither when it comes to performance nor visuals. However, some interesting findings regarding the judgment of visual quality were observed and presented. / Den här uppsatsen utforskar balansen mellan visuell kvalitéoch prestanda i 3D modeller för spel. Vidare eftersträvar den att utgöra ett stöd för nya 3D-modelleingskonstnärer för att skapa modeller som är både visuellt adekvata och optimerade för att renderas i realtid. Dessutom undersöks skillnaden mellan omdömet av den visuella kvalitén mellan de som är bekanta med 3D datorgrafik och de som inte är det. Många förklaringar gällande optimering av 3D grafik är högst tekniska och utgör en utmaning för grafiker att förståsig på och försummar dessutom ofta effekten av hur optimering påverkar resultatet rent visuallet. Genom att testa ett flertal 3D modeller, mäta tiden det tar för dem att renderas, samt omdömen gällande visuella intryck, drogs slutsatsen att bedömning av 3D modellering för spel är väldigt kontextuell. Inget definitivt och enkelt sätt att hitta balansen mellan visuella kvalitén upptäcktes. Varken gällande prestanda eller visuell kvalité. Däremot gjordes några intressanta upptäckter angående bedömningen av den visuella kvalitén som observerades och presenterades.

In this research we introduce a novel reading system that enables Individuals with Blindness<br />or Severe Visual Impairment (IBSVI) to have equivalent spatial reading experience to their<br />sighted counterparts, in terms of being able to engage in different reading strategies e.g.<br />scanning, skimming, and active reading. IBSVI are enabled to read in a self-paced manner<br />with spatial access to the original layout of any electronic text document. This system<br />renders text on iPad-type devices, and reads aloud each word touched by the user\'s finger.<br />The user could move her finger smoothly along the lines to read continuously with the<br />support of tactile landmarks. A tactile overlay on the iPad screen helps IBSVI to navigate<br />a page, furnishing a framework of tactile landmarks to give IBSVI a sense of place on the<br />page. As the user moves her finger along the tangible pattern of the overlay, the text on the<br />screen that is touched is rendered audibly to speech. The system supports IBSVI to develop<br />and maintain a cognitive map of the structure and the layout of the page. IBSVI are enabled<br />to fuse audio, tactile landmarks, and spatial information in order to read.<br />The system\'s initial design is founded on a theoretical hypothesis. A participatory design<br />approach with IBSVI consultants was then applied to refine the initial design. The re"fined<br />design was tested in a usability study, which revealed two major issues with the tested<br />design. These issues are related to the lack of instant feedback from the system (psycho-<br />motorical problem), and the lack of conveying the semantic level of the page structure.<br />We adapted the reader design to solve the usability problems. The improved design was<br />tested in an experience sampling study. The results showed a leap in the system usability.<br />IBSVI participants successfully self-paced read spatial text. Further reading support was<br />then added to the system to improve the user experience while reading and interacting with<br />the system. We tested the latest design of the reader system with respect to its featured<br />function of enabling self-paced reading and re-finding information. A decomposition study<br />was conducted to evaluate the main components of the system; the tactile overlay, and the<br />intelligent active reading support. The results showed that both components are required<br />to achieve the best performance in terms of efficiency, effectiveness, and spatial perception.<br />We conducted an evaluation study to compare our reader system to the state-of-the-art<br />iBook with VoiceOver. The results show that our reader system is more effective than iBook<br />with VoiceOver in finding previously read information and in estimating the layout of the<br />page, implying that IBSVI were able to construct a cognitive map for the pages they read,<br />and perform advanced reading strategies. Our goal is to to enable IBSVI to access digital<br />reading materials effectively, so that they may have equal learning opportunities as their<br />sighted counterparts. / Ph. D.

With an increase in processing power, more complex simulations have resulted in larger data size, with higher resolution and more variables. Many techniques have been developed to help the user to visualize and analyze data from such simulations. However, dealing with a large amount of multivariate data is challenging, time- consuming and often requires high-end clusters. Consequently, novel visualization techniques are needed to explore such data. Many users would like to visually explore their data and change certain visual aspects without the need to use special clusters or having to load a large amount of data. This is the idea behind explorable images (EI). Explorable images are a novel approach that provides limited interactive visualization without the need to re-render from the original data [40]. In this work, the concept of EI has been used to create a workflow that deals with explorable iso-surfaces for scalar fields in a multivariate, time-varying dataset. As a pre-processing step, a set of iso-values for each scalar field is inferred and extracted from a user-assisted sampling technique in time-parameter space. These iso-values are then used to generate iso- surfaces that are then pre-rendered (from a fixed viewpoint) along with additional buffers (i.e. normals, depth, values of other fields, etc.) to provide a compressed representation of iso-surfaces in the dataset. We present a tool that at run-time allows the user to interactively browse and calculate a combination of iso-surfaces superimposed on each other. The result is the same as calculating multiple iso- surfaces from the original data but without the memory and processing overhead. Our tool also allows the user to change the (scalar) values superimposed on each of the surfaces, modify their color map, and interactively re-light the surfaces. We demonstrate the effectiveness of our approach over a multi-terabyte combustion dataset. We also illustrate the efficiency and accuracy of our technique by comparing our results with those from a more traditional visualization pipeline.

[pt] Técnicas de visualização científica criam imagens na tentativa de revelar estruturas e fenômenos complexos. Técnicas ilustrativas têm sido incorporadas aos sistemas de visualizacão científica para melhorar a expressividade de tais imagens. A visualização de linhas caracteríticas é uma técnica importante para transmitir uma melhor informacão sobre a forma das superfícies. Neste trabalho, propomos combinar visualização volumétrica de malhas não estruturadas com isosuperfícies ilustradas. Isto é feito estendendo um algoritmo de traçado de raio em GPU para incorporar ilustração com linhas de variação extrema da iluminação(photic extremum lines), um tipo de linha característica que captura mudanças bruscas de luminância, revelando formas de um jeito perceptualmente correto. / [en] Scientic visualization techniques create images attempting to reveal complex structures and phenomena. Illustrative techniques have been incorporated to scientic visualization systems in order to improve the expressiveness of such images. The rendering of feature lines is an important technique for better depicting surface shapes and features. In this thesis, we propose to combine volume visualization of unstructured meshes with illustrative isosurfaces. This is accomplished by extending a GPU-based ray-casting algorithm to incorporate illustration with photic extremum lines, a type of feature lines able to capture sudden changes of luminance, conveying shapes in a perceptually correct way.

Vector graphics rendering is the subject of a large number of research papers. However, many of them lack results regarding animated vector graphics despite its importance in many fields. In this thesis the resolution independent rendering of animated graphics is studied. A testing platform is implemented to evaluate selected rendering backends based on state-of-the-art rendering algorithms and widely used vector graphics libraries. The selected rendering algorithms were selected because they were lacking results for animated graphics. The objectives of the work are achieved through the analysis of the results produced by the animation platform on specifically designed scenarios. The performance of the renderers is evaluated in terms of frame time and sensitivity to various parameters defining the animation. The results showed that the algorithms not originally designed for rendering animated graphics are applicable for this task but tradeoffs have to be made to choose a suitable rendering backend.

This master's thesis deals with terrain rendering using a modern algorithm for adaptive level of detail. It describes two currently most used graphical application interfaces and high-level libraries that use them and summarizes principles and features of several level-of-detail algorithms for terrain rendering. In more detail it then describes the implementation of Seamless patches for GPU-based terrain rendering algorithm.