The objective of this work is to create software implementing two algorithms for global ilumination computation. Iradiance and radiance caching should be implemented in CUDA framework on a graphics card (GPU). Parallel implementation on the GPU should improve algoritm speed compared to CPU implementation. The software will be written using an already done framework for global illumunation computation. That allows to focus on algorithm implementation only. This work should speed up testing of new or existing methods for global illumination computing, because saving and reusing of intermediate results can be used for other algorithms too. Powered by TCPDF (www.tcpdf.org)

Background. Real-time shadows in 3D applications have for decades been implemented with a solution called Shadow Mapping or some variant of it. This is a solution that is easy to implement and has good computational performance, nevertheless it does suffer from some problems and limitations. But there are newer alternatives and one of them is based on a technique called Voxel Cone-Tracing. This can be combined with a technique called Cascading to create Cascaded Voxel Cone-Tracing Shadows (CVCTS). Objectives. To measure the computational performance of CVCTS to get better insight into it and provide data and findings to help developers make an informed decision if this technique is worth exploring. And to identify where the performance problems with the solution lies. Methods. A simple implementation of CVCTS was implemented in OpenGL aimed at simulating a solution that could be used for outdoor scenes in 3D applications. It had several different parameters that could be changed. Then computational performance measurements were made with these different parameters set at different settings. Results. The data was collected and analyzed before drawing conclusions. The results showed several parts of the implementation that could potentially be very slow and why this was the case. Conclusions. The slowest parts of the CVCTS implementation was the Voxelization and Cone-Tracing steps. It might be possible to use the CVCTS solution in the thesis in for example a game if the settings are not too high but that is a stretch. Little time could be spent during the thesis to optimize the solution and thus it’s possible that its performance could be increased.

Abstract The report investigates computer generated (CG) lighting techniques with a focus on the rendering of interior architectural visualisations. With rapid advancements in CG technology, the demand and expectation for greater photorealism in visualisations are increasing. The tools to achieve this are widely available and fairly easy to apply; however, renderings on a local scale are still displaying functionality and lack visual appeal. The research discusses how design principles and aesthetics can be used effectively to create visual interest and display mood in the visualisation, with strong attention to the elements that are defined as the fundamentals in achieving photorealism. The focus is on a solid understanding of CG lighting techniques and principles in order to achieve high quality, dynamic visualisations. Case studies examine the work of lighting artist James Turrell and 3D artist Jose Pedro Costa and apply the findings to a creative project, encompassing the discussions in the report. The result is the completion of three photorealistic renderings of an interior visualisation, using different CG lighting techniques to convey mood. The research provides a platform for specialisation in the 3D environment and encourages a multidisciplinary approach to learning.

L'objectif de cette thèse est lerendu de scène virtuelles extrêmement détaillées.Nous nous intéressons plus particulièrementaux algorithmes de rendu de haute qualitéreposant sur du path tracing qui sont très largement utilisésdans l'industrie des effets spéciaux et pour calculerle rendu des films d'animations.Les grandes quantités de détail nécessaires à la modélisationde mondes virtuels crédibles soulèvent de sérieux problèmes d'efficacitédu rendu qui paralysent les studios et compliquent grandementle travail des artistes. Nous introduisons de nouveaux algorithmespour préfiltrer les objets 3D complexes à des échelles arbitraires,afin de réduire les temps de chargement, les coûts d'intersection des rayons lumineux,le calcul des matériaux et la quantité de bruit dans les images,le tout sans porter atteinte à la qualité du rendu.Nos contributions principales sont une nouvelle approchehybride de niveaux de détail qui allie les avantages des maillageset des représentations volumiques pour le préfiltrage des objets complexes àdes échelles arbitraires, ainsi qu'une nouvelle approchede préfiltrage pour le cas des volumes hétérogènes de haute résolution. / We address the problem of rendering extremely complex virtualscenes with large amounts of detail. We focuson high-end off-line rendering algorithms based on path tracing thatare intensively used in the special effects and 3D animation industries.The large amounts of detail required for creating believable virtual worldsraise important efficiency problemsthat paralyze production rendering pipelines andgreatly complicate the work of 3D artists.We introduce new algorithms for prefilteringcomplex 3D assets while preserving their appearanceat all scales, in order to reduce loading times,ray intersection costs, shading costs and Monte Carlo noise,without lowering the quality of rendered frames.Our main contributions are a new hybrid LODapproach that combines the benefits ofmeshes and volumetric representationsfor prefiltering complex 3D assets,as well as a new approach for prefilteringhigh-resolution heterogeneous participatingmedia.

Dans le domaine de la synthèse d'image, la simulation de l'apparence visuelle des matériaux nécessite, la résolution rigoureuse de l'équation du transport de la lumière. Cela implique d'incorporer dans les modèles tous les éléments pouvant avoir une influence sur la luminance spectrale énergétique reçue par l'œil humain. La caractérisation des propriétés de réflectance des matériaux, encore sujette à de nombreuses recherches, est très évoluée. Cependant, l'utilisation de cartes d'environnement, pour simuler leurs comportements visuels restent essentiellement trichromatiques. Caractériser la lumière naturelle avec précision, est une interrogation ancienne et il n'existe pas aujourd'hui de cartes d'environnement comportant à la fois les informations de luminance spectrale énergétique et de polarisations correspondant à des ciels réels. Il nous est donc apparu nécessaire, de proposer à la communauté de l'informatique graphique des environnements lumineux complets exploitables dans un moteur de rendu adapté en conséquence.Dans ce travail, nous exploitons des résultats issus d'autres domaines scientifiques tels que la météorologie, la climatologie..., pour proposer un modèle de ciel clair, c'est-à-dire sans nuage.Toutes les situations réelles ne pouvant pas être abordées par cette méthode, nous développons et caractérisons un dispositif de capture d'environnement lumineux incorporant à la fois, la gamme dynamique de l'éclairage, la répartition spectrale et les états de polarisation.Nous proposons, dans le but de standardiser les échanges, un format de données utilisable dans un moteur de rendu spectral, exploitant le formalisme de "Stokes - Mueller". / In the field of computer graphics, the simulation of the visual appearance of materials requires, a rigorous solving of the light transport equation. This implies to incorporate into models all elements that can influence the spectral received by human eyes. The characterization of the reflectance properties of materials, still subject to many researches is very advanced. However, the uses of environment maps, to simulate their visual behaviors remain essentially trichromaticity. Characterize the natural light with precision, is an old question. Today, there are no environment maps, including both spectral radiance and polarization informations, corresponding to a real sky. It was therefore necessary for us to design and propose to the computer graphics community a full of bright environments exploitable in a rendering engine adapted accordingly. In this work, we use the results of other scientific fields as meteorology, climatology..., to propose a new model of clear sky. As all actual situations are not addressed by this method, we develop and characterize an environment capturing device both incorporating the light dynamic range, the spectral distribution and the polarization states.

La synthèse d'images dites photoréalistes nécessite d'évaluer numériquement la manière dont la lumière et la matière interagissent physiquement, ce qui, malgré la puissance de calcul impressionnante dont nous bénéficions aujourd'hui et qui ne cesse d'augmenter, est encore bien loin de devenir une tâche triviale pour nos ordinateurs. Ceci est dû en majeure partie à la manière dont nous représentons les objets: afin de reproduire les interactions subtiles qui mènent à la perception du détail, il est nécessaire de modéliser des quantités phénoménales de géométries. Au moment du rendu, cette complexité conduit inexorablement à de lourdes requêtes d'entrées-sorties, qui, couplées à des évaluations d'opérateurs de filtrage complexes, rendent les temps de calcul nécessaires à produire des images sans défaut totalement déraisonnables. Afin de pallier ces limitations sous les contraintes actuelles, il est nécessaire de dériver une représentation multiéchelle de la matière. Dans cette thèse, nous construisons une telle représentation pour la matière dont l'interface correspond à une surface perturbée, une configuration qui se construit généralement via des cartes d'élévations en infographie. Nous dérivons notre représentation dans le contexte de la théorie des microfacettes (conçue à l'origine pour modéliser la réflectance de surfaces rugueuses), que nous présentons d'abord, puis augmentons en deux temps. Dans un premier temps, nous rendons la théorie applicable à travers plusieurs échelles d'observation en la généralisant aux statistiques de microfacettes décentrées. Dans l'autre, nous dérivons une procédure d'inversion capable de reconstruire les statistiques de microfacettes à partir de réponses de réflexion d'un matériau arbitraire dans les configurations de rétroréflexion. Nous montrons comment cette théorie augmentée peut être exploitée afin de dériver un opérateur général et efficace de rééchantillonnage approximatif de cartes d'élévations qui (a) préserve l'anisotropie du transport de la lumière pour n'importe quelle résolution, (b) peut être appliqué en amont du rendu et stocké dans des MIP maps afin de diminuer drastiquement le nombre de requêtes d'entrées-sorties, et (c) simplifie de manière considérable les opérations de filtrage par pixel, le tout conduisant à des temps de rendu plus courts. Afin de valider et démontrer l'efficacité de notre opérateur, nous synthétisons des images photoréalistes anticrenelées et les comparons à des images de référence. De plus, nous fournissons une implantation C++ complète tout au long de la dissertation afin de faciliter la reproduction des résultats obtenus. Nous concluons avec une discussion portant sur les limitations de notre approche, ainsi que sur les verrous restant à lever afin de dériver une représentation multiéchelle de la matière encore plus générale / Photorealistic rendering involves the numeric resolution of physically accurate light/matter interactions which, despite the tremendous and continuously increasing computational power that we now have at our disposal, is nowhere from becoming a quick and simple task for our computers. This is mainly due to the way that we represent objects: in order to reproduce the subtle interactions that create detail, tremendous amounts of geometry need to be queried. Hence, at render time, this complexity leads to heavy input/output operations which, combined with numerically complex filtering operators, require unreasonable amounts of computation times to guarantee artifact-free images. In order to alleviate such issues with today's constraints, a multiscale representation for matter must be derived. In this thesis, we derive such a representation for matter whose interface can be modelled as a displaced surface, a configuration that is typically simulated with displacement texture mapping in computer graphics. Our representation is derived within the realm of microfacet theory (a framework originally designed to model reflection of rough surfaces), which we review and augment in two respects. First, we render the theory applicable across multiple scales by extending it to support noncentral microfacet statistics. Second, we derive an inversion procedure that retrieves microfacet statistics from backscattering reflection evaluations. We show how this augmented framework may be applied to derive a general and efficient (although approximate) down-sampling operator for displacement texture maps that (a) preserves the anisotropy exhibited by light transport for any resolution, (b) can be applied prior to rendering and stored into MIP texture maps to drastically reduce the number of input/output operations, and (c) considerably simplifies per-pixel filtering operations, resulting overall in shorter rendering times. In order to validate and demonstrate the effectiveness of our operator, we render antialiased photorealistic images against ground truth. In addition, we provide C++ implementations all along the dissertation to facilitate the reproduction of the presented results. We conclude with a discussion on limitations of our approach, and avenues for a more general multiscale representation for matter

[pt] Neste trabalho aplicamos o método de oclusão implícita para acelerar o tempo de cálculo e renderização de isosuperfícies em dados volumétricos regulares. Dado um campo escalar contínuo f sobre um domínio D (onde Dé convexo) e um isovalor w, a oclusão implícita explora a continuidadede f para determinar os limites de visibilidades sem a necessidade de calcular a isosuperfície explicitamente. Aplicamos esta técnica para obter também as silhuetas visíveis das isosuperfícies. / [en] In this work we apply the Implicit Occluders method for optimizing the computation and rendering of isosurfaces in regular volumetric data. Given a continuous scalar field f over a domain D and an isovalue w, Implicit Occluders exploits the continuity of f to determine visibility bounds without the need for computing the isosurface explicitly. We apply this technique to obtain also the visible silhouettes of isosurfaces.

A estereoscopia é a área do conhecimento que aborda a visão em três dimensões, mas se limita, por definição, apenas às técnicas que possibilitam a reconstituição de uma cena tridimensional observada através de pelo menos dois pontos de vista distintos, que no caso dos seres humanos é a cena reconstituída no cérebro a partir das imagens obtidas pelos olhos. Inicialmente, o presente trabalho consolida os principais conceitos e técnicas desta área abrangente, para em seguida propor formas de análise, comparação e classificação de técnicas de estereoscopia através de conceitos teóricos e métricas qualitativas e quantitativas. Complementando esta proposta, com base na revisão da literatura e nos resultados experimentais, a pesquisa busca avaliar vantagens e desvantagens entre as técnicas estereoscópicas e na estereoscopia como um todo, para alimentar discussões, tendências e desafios encontrados na aplicação da estereoscopia a sistemas de Realidade Aumentada (RA), em particular sistemas de tele-presença com vídeo-avatar, e na área de jogos. / Stereoscopy is the area of knowledge that addresses three dimensional vision, but its restricted to, by definition, the techniques that allows the reconstruction of a three dimensional scene observed from two different points of view at least, in the case of human beings it is the scene reconstructed in the brain from the images obtained by the eyes. Initially, the present work consolidates the main concepts and techniques of this extended area, considering, after that, ways of analysis, comparison and classification of stereoscopy techniques through qualitative and quantitative metrics and theorical data. Additionally, based on literature review and in experimental results, the research try\'s to evaluate advantages and disadvantages between stereoscopy techniques and in stereoscopy as a whole, to stimulate discussion, trends and challenges found when merging stereoscopy to Augmented Reality (AR) systems, in particular tele-presence systems with video-avatar, and computer games.

Os métodos construtivos de revestimento externo produzidos com argamassa vêm evoluindo ao longo do tempo, apresentando como maior mudança a substituição da aplicação manual pela projeção mecânica. Atualmente destaca-se no mercado o sistema de execução de revestimento externo com argamassa industrializada e projeção mecânica contínua com bombas helicoidais. Por se tratar de uma tecnologia ainda não muito utilizada pelas construtoras brasileiras, faltam dados confiáveis acerca de seu potencial de ganho de produtividade, redução de perdas, diminuição de contingente de mão de obra, exigências de infraestrutura para aplicação e custos envolvidos. Sem parâmetros confiáveis, adotar a tecnologia significa assumir um nível de risco elevado e isto dificulta a tomada de decisão por parte das construtoras e, por consequência, dificulta-se a evolução tecnológica. Buscando contribuir para o necessário avanço nas tecnologias de produção de revestimentos de edifícios, o objetivo desta pesquisa é estabelecer parâmetros em relação à tecnologia de produção de revestimentos de fachada que empregam argamassa com projeção contínua. Para tanto, buscou-se informações em referências como teses, dissertações, textos técnicos, normas nacionais, dentre outras, bem como, acompanhou-se e avaliou-se os resultados da implantação de um método construtivo de revestimento de argamassa com projeção mecânica contínua em uma construtora de São Paulo. Foram realizados um protótipo e um piloto que contribuíram para o desenvolvimento da tecnologia por meio de apresentação de soluções para os problemas encontrados, do levantamento de melhores práticas e de dados para o cálculo de índices de produtividade e perda. Buscou-se, portanto, a consolidação da tecnologia de projeção contínua na construtora anteriormente mencionada e no mercado em geral. / The external rendering constructive methods produced with mortar have evolved over time and the greater change in it was the replacement of manual application by mechanical projection. The currently most prominent system in the market is the outer rendering execution system with industrialized mortar and continuous mechanical projection with helical pumps. Since this technology is not widely used by Brazilian construction companies, there is a lack of reliable data regarding its productivity gain potential, loss reduction, reduction of hand quota of work, infrastructure required for application and costs involved. Without reliable parameters, the decision to implement this technology is highly risky which does not encourage constructions companies to decide to apply it and, therefore, makes its technological evolution harder to be achieved. Aiming to contribute to the necessary advancement in technology for the production of rendering, this research has the objective to establish parameters to the rendering technology that uses industrialized mortar with continuous projection. With this purpose, it was used as source and reference the specialized literature such as thesis, dissertations and scientific papers, as well as both national norms. In addition, the research included the monitoring and assessment of the results from the implementation of a rendering execution method with continuous mechanical projection in a construction company in Sao Paulo. A prototype and a pilot scale were built and they contributed to the development of this technology by presenting solutions for problems identified and through the mapping of best practices and gathering data that allowed the calculation of productivity and loss rates. The goal was, thus, to consolidate the continuous projection technology in the above-mentioned construction company as well as in the market in a broader way.

Diversos estudos relacionados com o mercado de capitais têm investigado os disclosures obrigatório e voluntário, os seus efeitos e também os motivos que levam as organizações a realizá-los ou não. Entretanto, são incipientes estudos que investigam o disclosure em instituições de ensino. Nesse sentido, o objetivo desta tese é de realizar uma análise comparativa, sob a abordagem da teoria da divulgação, entre o índice de disclosure e a importância atribuída por stakeholders a informações consideradas relevantes para fins de divulgação em Instituições e Ensino Superior Filantrópicas do Brasil IESFB. O estudo desenvolve-se a partir da análise da população composta de 146 entidades cadastradas no Conselho Nacional de Assistência Social CNAS. Primeiramente foi desenvolvido o Índice de Disclosure das Instituições de Ensino Superior Filantrópicas do Brasil IDIESFB, mensurado a partir das características qualitativas de disclosure divididas em quatros grupos: (i) visão geral, (ii) desempenho dos serviços, (iii) desempenho financeiro e (iv) situação física e financeira, conforme proposta de Coy, Dixon e Tower (1993). Posteriormente, com a utilização da técnica delphi e tendo por base o estudo de Coy e Dixon (2004), buscou-se captar a percepção de stakeholders sobre quais informações eles consideram importante divulgar com relação às IESFB. Os resultados revelam a existência de um gap entre o que as IESFB divulgam e o que os participantes da técnica delphi consideram importante as IESFB divulgar. Os resultados mostram, ainda, que o índice de disclosure das IESFB, se comparado com os resultados dos períodos de 1993 e 1994, apresentados no estudo de Nelson, Banks e Fischer (2003), está acima do índice de disclosure das universidades canadenses, próximo ou igual ao das universidades da Inglaterra, País de Gales e Irlanda do Norte e bem abaixo do das universidades da Austrália e Nova Zelândia. A pesquisa também apontou que menos de 33% das IESFB realizam disclosure voluntário e que a maioria só apresenta disclosure obrigatório, indicando que são poucas, ainda, as instituições que se preocupam com a accountability pública além das exigências legais. O presente trabalho contribui para ampliar a literatura nacional e internacional sobre disclosure em instituições de ensino ao apresentar a realidade das IESFB, bem como a falta de motivação e de regulação para que as mesmas evidenciem mais suas ações, possibilitando, dessa forma, o desenvolvimento de futuras pesquisas, principalmente no que diz respeito aos motivos que levam as IESFB a não realizarem o disclosure voluntário. / Several studies related to the capital market have investigated the voluntary and mandatory disclosures, their effects and also the reasons that lead the organization to do it or not. However, they are incipient the studies that investigate the disclosure in educational institutions. In this sense, the objective of this these is to make a comparative analysis, under the accountability theory approach, between the index of disclosure and the importance given by stakeholders to information considered relevant aiming at the accountability in Philanthropic Institutions of Higher Education of Brazil - PIHEB. The study is developed from the analysis of a population of 146 entities that are drawn up a cadastre in the National Council of Social Assistance - NCSA. Firstly, it was developed the Index of Disclosure of the Institutions of Higher Education of Brazil - IDIHEB measured from qualitative characteristics of disclosure divided in four groups: (i) general view, (ii) services performance, (iii) financial performance and (iv) physical and financial situation, developed and used in the study of Coy, Dixon and Tower (1993). Farther, with the use of the delphi technique and having as basis the study of Coy and Dixon (2004), it was searched the capture of stakeholders perception about what information they consider important to account in relation to the PIHEB. The results reveal the existence of a gap between what the PIHEB account and the participants of the delphi technique consider important the PIHEB to account. The results show that the index of disclosure of the PIHEB, if compared to the periods of 1993 and 1994 results, presented in the studies made by Nelson, Banks and Fischer (2003) is above the average of disclosure of Canadian universities, near or equal to the universities from England, Wales and North Ireland and much below the index presented by the universities from Australia and New Zealand.The search also pointed that less than 33% of PIHEB prepare voluntary disclosure and that the majority only prepares mandatory disclosure, showing that are few, yet, the institutions that are concerned about public accountability beyond legal requirements.The present work contributes to broaden national and international literature about disclosure in institutions when presenting the reality of the PIHEB, as well as the lack of motivation and regulation for them to account their actions more often, making possible, in this way, the development of future research, mainly concerning the reasons that lead the PIHEB not to make the voluntary disclosure.