Submitted by Erika Demachki (erikademachki@gmail.com) on 2017-02-13T17:22:05Z No. of bitstreams: 2 Dissertação - Marina de Oliveira Campos - 2014.pdf: 13269135 bytes, checksum: 836275079c9f910e9129b36c9fe2c2fc (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-02-14T09:43:12Z (GMT) No. of bitstreams: 2 Dissertação - Marina de Oliveira Campos - 2014.pdf: 13269135 bytes, checksum: 836275079c9f910e9129b36c9fe2c2fc (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-02-14T09:43:12Z (GMT). No. of bitstreams: 2 Dissertação - Marina de Oliveira Campos - 2014.pdf: 13269135 bytes, checksum: 836275079c9f910e9129b36c9fe2c2fc (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2014-09-25 / Bond is the crucial property of a rendering system. It is the combining result of several mortar and concrete substrates`s properties. Then, isolated studies about this subject, with single variables are insuficient. The ideal perfect understanding of the stresses, of the materials and of the tensile and shear bond sthength properties can lead to advances in the rendering system`s quality. Most of the stresses acting in rendering systems are shear stresses and, however, there is a large gap in shear bond strength knowledge. There is no standard method for the evaluation of this property. Thus, the main objective of this dissertation is to propose a laboratory method to evaluate the shear bond strength of rendering mortar in a rendering system, by the adaptation of the standartized method ASTM D 3080, used for direct shear tests in soil. Furthermore, this study aimed to evaluate the substrates`s characteristics (water cement ratio and surface roughness) and the rendering mortar`s characteristics (mix proportion) in the tensile and shear bond strength, along with doing the correlation between the two properties. In order to do so, the experimental programme included studies of tensile bond strength (Rat), using the ABNT NBR 13528 and shear bond strength studies (Rac), using the ASTM D 3080 adaptation. To the Rat tests it was prepared 10 concrete substrates that was coated with rendering mortar with 3 mix proportion (1:2:9, 1:1:6 and 1:0,5:3,4). For the concrete substrates, it was varied the water cement ratio (0,35, 0,50, 0,65 and 0,80) and the surface roughness (a smooth R1 and a roughened R2 one). For the Rac studies it was prepared 160 concrete substrates, with a smaller dimension, using the water cement ratio of 0,65. In the Rac tests the studied variables were the surface roughness (R1 and R2), the mortar mix proportion (1:1:6 and 1:0,5:3,4) and the applied normal tension (0,01 MPa, 0,06 MPa, 0,09 MPa and 0,15 MPa). Besides, it was performed an extensive characterization of the rendering mortars and the substrate`s concrete. As conclusions, the research proved that the proposed shear bond method for rendering mortar was apropriate, with low deviation coefficient of the results (6%) and with sensibility to the imposed variables (diferent mortars and substrates). The mortar mix proportion and the roughness surface of the substrates do influence in Rat and Rac, and the first one is the most influent one. The water cement ratio of the substrates concrete also influences the Rat. Besides, it was found a logarithmic correlation between Rat and Rac, with R2value of 0,87. / A aderência é a propriedade fundamental de um sistema de revestimento de argamassa aderido. Por ser a aderência resultado da combinação de várias propriedades da interface entre argamassa e substrato, estudos isolados, com variáveis únicas, são insuficientes. O perfeito entendimento do comportamento das tensões, dos materiais e das propriedades de resistência de aderência (tração e cisalhamento) podem conduzir a avanços na qualidade dos revestimentos de argamassa. A maioria das tensões atuantes nos sistemas de revestimentos são cisalhantes e, no entanto, existe uma grande lacuna no conhecimento acerca da resistência de aderência ao cisalhamento. Ainda não existe nenhum método normalizado para a avaliação dessa propriedade. Dessa forma, o objetivo principal da dissertação é o de propor um método de avaliação, em laboratório, da resistência de aderência ao cisalhamento para revestimentos de argamassa, a partir da adaptação do método normalizado pela ASTM D 3080 de cisalhamento direto em solo. Ademais, o trabalho visou avaliar a influência das características do substrato (a/c e rugosidade) e das argamassas (diferentes proporcionamentos) nas resistências de aderência à tração e ao cisalhamento, além de correlacionar os resultados obtidos nesses dois ensaios. Para tanto, o programa experimental abrangeu estudos de resistência de aderência à tração (Rat), empregando o método ABNT NBR 13528 e estudos de resistência de aderência ao cisalhamento (Rac), realizados conforme adaptação do método ASTM D 3080. Para os ensaios de Rat foram moldados 10 substratos simulando pilares, os quais foram revestidos com argamassas projetadas em três proporcionamentos, em volume, (1:2:9, 1:1:6 e 1:0,5:3,4) cimento, cal e areia úmida. Com relação ao substrato foram variadas a relação a/c (0,35, 0,50, 0,65 e 0,80) e a rugosidade (lisa – R1 e rugosa – R2). Para os estudos de resistência de aderência ao cisalhamento (Rac), foram moldados 160 substratos de menor dimensão utilizando o concreto de relação água/cimento de 0,65. Nessa etapa, as variáveis testadas foram a rugosidade (R1 e R2), o proporcionamento das argamassas (1:1:6 e 1:0,5:3,4), além da tensão normal aplicada (0,01MPa, 0,06MPa, 0,09MPa e 0,15MPa) Adicionalmente foi realizada uma ampla caracterização no estado endurecido das argamassas de revestimento e dos concretos dos substratos. Como principais conclusões da pesquisa, tem-se que o método proposto para determinação da resistência de aderência ao cisalhamento mostrou-se adequado, com baixo coeficiente de variação dos resultados (em média 6%) e com sensibilidade às variações impostas (diferentes argamassas e substratos). Observou-se que o proporcionamento da argamassa e a rugosidade do concreto dos substratos possuem influência significativa nas resistências de aderência à tração e ao cisalhamento, sendo o primeiro fator o mais influente. A relação água/cimento do concreto dos substratos também possui influência na resistência de aderência à tração. Adicionalmente, foi encontrada uma boa correlação entre Rat e Rac, com um valor de R2 de 0,87 para uma função do tipo logarítmica (ln).

M.Sc. / Real-time terrain rendering (RTTR) is an exciting eld in computer graphics. The algorithms and techniques developed in this domain allow immersive virtual environments to be created for interactive applications. Many di culties are encountered in this eld of research, including acquiring the data to model virtual worlds, handling huge amounts of geometry, and texturing landscapes that appear to go on forever. RTTR has been widely studied, and powerful methodologies have been developed to overcome many of these obstacles. Complex natural terrain features such as detailed vertical surfaces, overhangs and caves, however, are not easily supported by the majority of existing algorithms. It becomes di cult to add such detail to a landscape. Existing techniques are incredibly e cient at rendering elevation data, where for any given position on a 2D horizontal plane we have exactly 1 altitude value. In this case we have a many-to-1 mapping between 2D position and altitude, as many 2D coordinates may map to 1 altitude value but any single 2D coordinate maps to 1 and only 1 altitude. In order to support the features mentioned above we need to allow for a many-to-many mapping. As an example, with a cave feature for a given 2D coordinate we would have elevation values for the oor, the roof and the outer ground. In this dissertation we build upon established techniques to allow for this manyto- many mapping, and thereby add support for complex terrain features. The many-to-many mapping is made possible by making use of geometry images in place of height-maps. Another common problem with existing RTTR algorithms is texture distortion. Texturing is an inexpensive means of adding detail to rendered terrain. Many existing technique map texture coordinates in 2D, leading to distortion on steep surfaces. Our research attempts to reduce texture distortion in such situations by allowing a more even spread of texture coordinates. Geometry images make this possible as they allow for a more even distribution of sample positions. Additionally we devise a novel means of blending tiled texture that enhances the important features of the individual textures. Fully sampled terrain employs a single global texture that covers the entire landscape. This technique provides great detail, but requires a huge volume of data. Tiled texturing requires comparatively little data, but su ers from disturbing regular patterns. We seek to reduce the gap between tiled textures and fully sampled textures. In particular, we aim at reducing the regularity of tiled textures by changing the blending function. In summary, the goal of this research is twofold. Firstly we aim to support complex natural terrain features|speci cally detailed vertical surfaces, over-hangs and caves. Secondly we wish to improve terrain texturing by reducing texture distortion, and by blending tiled texture together in a manner that appears more natural. We have developed a level of detail algorithm which operates on geometry images, and a new texture blending technique to support these goals.

Det finns flera olika metoder och tekniker för tredimensionell rendering, alla med olika för- och nackdelar som lämpar sig för olika applikationer. Voxelbaserad rendering har använts flitigt inom vetenskapliga områden, främst inom det medicinska för visualisering av volymetrisk data. Tekniken används nu inom flera olika områden för tredimensionell rendering, t.ex. i datorspel, i matematiska applikationer och vid geologisk rekonstruktion. I den här rapporten kommer voxelbaserad rendering med Marching Cubes-algoritmen undersökas för att se hur den lämpar sig för realtidsapplikationer. Området behandlas dels teoretiskt, men även praktiskt då en implementering av Marching Cubes gjordes för att genomföra några tester för att se hur prestandan påverkades. Av testerna framkom det tydligt att algoritmen lämpar sig väl för realtidsapplikationer och dagens grafikkort. Viss optimering krävs dock för att kunna utnyttjas på bästa sätt. / There are lots of different methods and techniques for three-dimensional rendering, everyone with different advantages and disadvantages that suits different applications. Voxel-based rendering has been used frequently within the scientific area, mainly within medicin for visualization of volumetric data. The technique is now used within many different areas for three-dimensional rendering, e.g. in computer games, in mathematical applications and in geological reconstruction. In this report voxel-based rendering with Marching Cubes algorithm will be researched to see how it suits for real-time applications. The area will partly be dealt with theoretically, but also practically as an implementation of Marching Cubes was done to run some tests to see how the performance was affected. From the tests it appeared cleary that the algorithm is well suited for real-time applications and today's graphics card. Though some optimization is needed to fully take advantage of it.

Trots den senaste tidens hårdvaruutveckling är realtidsrendering av stora folkmassor fortfarande ingen trivial uppgift. Denna uppgift beskrivs som crowd rendering. Effektiv crowd rendering bygger ofta på instansiering, men instansiering kommer med ett problem, det skapar kloner. Denna uppsats syftar till att undersöka och utvärdera ett antal tekniker som används för att skapa mångfald för instansierade modeller. Dessa tekniker kommer tillsammans att kallas varierad instansiering. Ett annat mål är att avgöra hur många modeller som behövs för att varierad instansiering skall betala sig i jämförelse med icke- instansierad utritning. Metoden som används är att mäta tiden för varje uppdatering på GPU för varje teknik med hjälp av ett mätinstrument. Varje teknik har implementerats i en applikation som skapats speciellt för detta ändamål. Analysen av mätningarna resulterade i tre kategorier. Kategorierna är GPU procentuell arbetsbörda stigande för instans avtagande för polygon, sjunkande för instans avtagande för polygon och jämn för instans och polygon. Antalet instanser som behövs för varierad instansiering skall betala sig i jämförelse med en icke- instansierad utritning bestämdes till någonstans mellan 100 och 300 modeller, beroende på antalet polygoner.

Rendering of skin and translucent materials as a real-time solution for a game engine.

This thesis describes methods for advanced visualization of 3D data. Order-independent transparent data between multiple datasets of varying types can be combined using an A-buffer. In this thesis, an implementation of such a buffer is presented. An optimisation of the A-buffer, based on the discarding of unnecessary fragments will be presented. A line integral convolution method for 3D volumes will also be presented, where noise input, and resolution of the input- compared to output volumes will be discussed. The resulting method is able to visualize multiple types of data with order-independent transparency. The rendering speed is generally fast enough for an interactive user-experience.

As the volumes are entering the world of computer graphics the pure volume visualisation becomes a more important tool in for example research and medical applications. But the advance in haptics --- force feedback from the computer --- is behind. In volume haptics no equal to the proxy method so popular in surface haptics has yet emerged. Some implementations of volume haptics even use surfaces as intermediate representations so that surface haptics can be used. The intention of this work was to create natural feeling haptic feedback from volumetric density data using pure volume haptics. The haptic algorithm would be implemented in Reachin API for the Reachin Desktop Display, together with other parts to build up a usable volume visualisation environment. To achieve the feeling of stiffness and friction dependent on tissue type, a proxy based method was developed. In the volume the proxy is constrained by virtual surfaces defined by the local gradient. This algorithm was implemented in a volume haptics node and for visualisation a volume renderer node was implemented. These nodes can be used to setup different volume visualisation environments using VRML.

Since grass is abundant on our planet it plays an important role in the rendering of many different outdoor scenes. This study focuses on the real-time rendering of many individual grass blades with geometry. As a grass blade in real life is very thin and have a simple shape it can be represented with only a handful of vertices. The challenge is introduced when a meadow of grass is to be rendered as it can contain billions of grass blades. Two different algorithms were developed; one which use traditional vertex buffers to store and render the grass blades while the other makes use of textures. Quantitative data was generated from these algorithms. Among this data were images of the scene. These images were subjected to a questionnaire to collect qualitative information about the grass. All the generated data was then analyzed and interpreted to find advantages and disadvantages of the algorithms. The buffer-based algorithm was found to be slightly more computationally efficient compared to the texture-based algorithm. The quality of the visual result was perceived to be towards good while the realism was perceived as mediocre at best. The advantage of the texture-based algorithm is that it allows more options to handle the grass blades data when rendering. Using the terrain data to generate the grass blades was concluded to be advantageous. The realism of the grass could have been improved by using a grass blade texture as well as introducing variety in density and grass species. / Eftersom gräs är rikligt på vår planet spelar den en viktig roll vid renderingen av många olika utomhusscener. Denna studie fokuserar på realtidsrendering av många individuella gräsblad med geometri. Eftersom ett gräsblad i verkligheten är mycket tunnt och har en enkel form kan den representeras med endast en handfull vertiser. Utmaningen introduceras när en äng av gräs ska renderas eftersom som den kan innehålla miljarder gräsblad. Två olika algoritmer utvecklades, en som använder traditionella vertex buffrar för att lagra och rendera gräsbladen medan den andra använder sig av texturer. Kvantitativ data genererades från dessa algoritmer. Bland denna data fanns bilder av scenen. Dessa bilder utsattes för ett frågeformulär för att samla in kvalitativ information om gräset. All den data som genereras analyserades och tolkades för att hitta fördelar och nackdelar med algoritmerna. Den bufferbaserade algoritmen upptäcktes vara beräkningsmässigt effektivare jämfört med den texturbaserade algoritmen. Den upplevda kvalitén på det visuella resultatet ansågs vara närmare bra medan realismen uppfattades som medioker i bästa fall. Fördelen med den texturen-baserad algoritm är att den tillåter fler möjligheter att hantera gräsblads-data vid rendering. Slutsatsen av att använda terrängens data för att generera gräsbladen sågs vara fördelaktigt. Realismen av gräset kunde förbättrats genom att använda en gräsblads-textur, samt variation i densitet och gräsarter.

Computer gamers demand more realistic effects for each release of a new game. This final year project is concerned with deforming the geometry in a terrain rendering environment. The intension is to increase the resolution where the original resolution of the terrain is not enough to cater for all the details associated with a deformation, such as an explosion. An algorithm for extending the maximum available resolution was found, the DEXTER algorithm, but calculations have shown that it has a too high memory consumption to be feasible in a game environment. In this project, an algorithm has been implemented, based on the DEXTER algorithm, but with some structural changes. The algorithm which has been implemented increases the resolution, if needed, where a deformation occurs. The increased resolution is described by b-spline surfaces, whereas the original resolution is given by a height map. Further, graphics primitives are only allocated to a high resolution region, when needed by the refinement process. It has been found that by using dynamic blocks of graphics primitives, the amount of RAM consumed can be lowered, without a severe decrease in rendering speed. However, the algorithm implemented has been found to suffer from frame rate drops, if too many high resolution cells need to be attached to the refinement process during a single frame. Is has been concluded that the algorithm, which is the result of this final year project, is not suitable for a game environment, as the memory consumption is still too high. The amount of time spent on refining the terrain can also be considered too much, as no time is left for other aspects of a game environment. The algorithm is however considered a good choice concerning deformations, as the updates needed in association with a deformation, can be kept small and localized, according to the DEXTER structure. Also, the b-spline surfaces offer more freedom over the deformation, compared to using a height map.

Three-dimensional computer graphics enjoys a wide range of applications of which games and movies are only few examples. By incorporating three-dimensional computer graphics in to a simulator the simulator is able to provide the operator with visual feedback during a simulation. Simulators come in many different flavors where flight and radar simulators are two types in which three-dimensional rendering of large terrains constitutes a central component. Ericsson Microwave Systems (EMW) in Skövde is searching for an algorithm that (a) can handle terrain data that is larger than physical memory and (b) has an adjustable error metric that can be used to reduce terrain detail level if an increase in load on other critical parts of the system is observed. The aim of this paper is to identify and evaluate existing algorithms for terrain rendering in order to find those that meet EMW: s requirements. The objectives are to (i) perform a literature survey over existing algorithms, (ii) implement these algorithms and (iii) develop a test environment in which these algorithms can be evaluated form a performance perspective. The literature survey revealed that the algorithm developed by Lindstrom and Pascucci (2001) is the only algorithm of those examined that succeeded to fulfill the requirements without modifications or extra software. This algorithm uses memory-mapped files to be able to handle terrain data larger that physical memory and focuses on how terrain data should be laid out on disk in order to minimize the number of page faults. Testing of this algorithm on specified test architecture show that the error metric used could be adjusted to effectively control the terrains level of detail leading to a substantial increase in performance. The results also reveal the need for both view frustum culling as well a level of detail algorithm to achieve fast display rates of large terrains. Further the results also show the importance of how terrain data is laid out on disk especially when physical memory is limited.