EG2007
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Item 3D Shape Description and Matching Based on Properties of Real Functions(The Eurographics Association, 2007) Biasotti, Silvia; Falcidieno, Bianca; Frosini, Patrizio; Giorgi, Daniela; Landi, Claudia; Marini, Simone; Patané, Giuseppe; Spagnuolo, Michela; Karol Myszkowski and Vlastimil HavranThis tutorial covers a variety of methods for 3D shape matching and retrieval that are characterized by the use of a real-valued function defined on the shape (mapping function) to derive its signature. The methods are discussed following an abstract conceptual framework that distinguishes among the three main components of these class of shape matching methods: shape analysis, via the application of the mapping function, shape description, via the construction of a signature, and comparison, via the definition of a distance measure. Goal of the tutorial is to facilitate the understanding of the performance of the various methods by a methodical analysis of the properties of various methods at the three different stages.Item An Accurate Implicit Field Representation for Meshes and Its Adapted Triangulation Algorithms(The Eurographics Association, 2007) Fournier, Marc; Dischler, J. - M.; Bechmann, D.; Paolo Cignoni and Jiri SochorThe classic implicit scalar field distance transform representation of a mesh is very useful to perform many mesh processing operations and to obtain better results than with other methods. In this paper we propose a new and more accurate implicit vector field distance transform representation of a mesh. We adapt Marching Cube and Marching Triangle, the two most widely used triangulation algorithms, to our new vector field representation to correctly reconstruct the final mesh after data processing in the implicit domain. According to a reliable surface error metric, we show our new vector field is more accurate than the classic scalar field to implicitly represent a mesh. We adapt to our vector field a previously introduced mesh denoising algorithm performed on the scalar field. Results show mesh denoising with our vector field outperforms the one with classic scalar field in terms of an error metric comparison.Item Adaptive Abstraction of 3D scenes in Real-Time(The Eurographics Association, 2007) Redmond, Niall; Dingliana, John; Paolo Cignoni and Jiri SochorWe present an approach for creating abstracted renderings of 3D scenes in real-time. We create painterly renderings with edge detail using varying levels of abstraction dependent on regions of interest within a scene. Image space techniques are used to make the system real-time and as non-invasive as possible. This approach can also use object space information to segment the scene into visually important objects and unimportant data and background. Interactive frame rates are achieved by using graphics hardware to perform the computations.Item Advanced Topics in Virtual Garment Simulation(The Eurographics Association, 2007) Thomaszewski, Bernhard; Wacker, Markus; Straßer, Wolfgang; Lyard, Etienne; Luible, C.; Volino, Pascal; Kasap, M.; Muggeo, V.; Magnenat-Thalmann, Nadia; Karol Myszkowski and Vlastimil HavranFor more than two decades, cloth simulation has been an active research area in computer graphics. In order to create efficient high-quality animations, techniques from many research fields have to be thoroughly combined. The ongoing interest in this field is also due to the multidisciplinary nature of cloth simulation which spurs development and progress in collision detection, numerical time integration, constrained dynamics, or motion control, to name just a few areas. Beyond the very basic approaches, the complexity of the material can be daunting if no guidance is given. It is therefore the goal of this tutorial to provide the reader with an introduction and a guideline to the relevant matter. In order to provide a concise review, we will focus on advanced topics in cloth simulation, shedding light on both theoretical and practical aspects. This will pave the ground for those willing to implement a contemporaneous cloth simulation system as well as researchers who consider to start working in this area.Item Analysis of the Pulmonary Vein Ostia using Cardiac 4DCT for Radiosurgical Ablation(The Eurographics Association, 2007) Sumanaweera, Thilaka; Conti, Francois; Maguire, Patrick; Paolo Cignoni and Jiri SochorA software tool to analyze 4D cardiac CT data sets for planning radiosurgical ablations in the heart is presented. Volume rendering and data processing are performed using a GPU. The user visualizes the data from inside the left atrium and defines the target in 3D using an intuitive user interface. A haptic input device lets the user measure motion at the ostia of the pulmonary veins for radiosurgical treatment planning. This tool has been used effectively for generating radiation treatment plans for animal studies.Item Applications of Information Theory to Computer Graphics(The Eurographics Association, 2007) Sbert, Mateu; Feixas, Miquel; Rigau, Jaume; Viola, Ivan; Chover, Miguel; Karol Myszkowski and Vlastimil HavranWe present different applications of information theory to computer graphics, based on the use of the measures of entropy, mutual information, f-divergences and generalized entropies. The application areas are hierarchical radiosity, adaptive ray-tracing, selection of best viewpoints, object and scene exploration, mesh saliency, mesh simplification and scientific visualization. We also give some hints on information-theoretic applications to object recognition and image processing.Item The Arnolfini Portrait in 3D - Creating Virtual World of a Painting with Inconsistent Perspective(The Eurographics Association, 2007) Jansen, Philip H.; Ruttkay, Zsofia M.; David B. Arnold and Andrej FerkoWe report on creating a 3d virtual reconstruction of the scene shown in "The Arnolfini Portrait" by Jan van Eyck. This early Renaissance painting, if painted faithfully, should confirm to one-point perspective, however it has several vanishing points instead of one. Hence our 3d reconstruction had to be based on some, from an art historian s point of view plausible assumptions on choosing a unique vanishing point and measures of certain items in the scene. We compare our approach to similar reconstructions by others. Using professional modeling and image processing computer tools, we created a 3d reconstruction of the geometry of the interior, the textures and the lighting. A perspective view of this model is compared to the original painting, showing high fidelity, but at the same time also large local mismatches due to the inconsistent handling of parallel lines in the original painting, as well as some differences in the reflected image in the mirror. A reconstruction such as ours provides new details of the original scene for scholars, is useful for art historians to find out more about the way the painting was created, and could be used as an installation for exploration in museums or other learning environments by the general public.Item Automated Combination of Real-Time Shader Programs(The Eurographics Association, 2007) Trapp, Matthias; Döller, Jürgen; Paolo Cignoni and Jiri SochorThis work proposes an approach for automatic and generic runtime-combination of high-level shader programs. Many of recently introduced real-time rendering techniques rely on such programs. The fact that only a single program can be active concurrently becomes a main conceptual problem when embedding these techniques into middleware systems or 3D applications. Their implementations frequently demand for a combined use of individual shader functionality and, therefore, need to combine existing shader programs. Such a task is often timeconsuming, error-prone, requires a skilled software engineer, and needs to be repeated for each further extension. Our extensible approach solves these problems efficiently: It structures a shader program into code fragments, each typed with a predefined semantics. Based on an explicit order of those semantics, the code fragments of different programs can be combined at runtime. This technique facilitates the reuse of shader code as well as the development of extensible rendering frameworks for future hardware generations. We integrated our approach into an object-oriented high-level rendering system.Item Bridging Semantic Web and Digital Shapes(The Eurographics Association, 2007) Papaleo, Laura; Floriani, Leila De; Hendler, Jim; Paolo Cignoni and Jiri SochorSince the volume of multimedia content available on the Web is continuously increasing, a clear need for advanced techniques capable of performing an effective retrieval and management of such data. In this context, in order to reason on digital shapes and their associated semantic, we see a growing interest in exploiting the potential of the Semantic Web in different research fields. We present here the design and initial development of our new system, that we call be-SMART for inspecting digital 3D shapes by extracting geometrical and topological information from them and for structuring and annotating these shapes using ontology-driven metadata. We describe the general structure of the system, its modules and their mutual relations. We also provide motivations for further work in developing new techniques for managing 3D models on the Web.Item Capturing Reflectance - From Theory to Practice(The Eurographics Association, 2007) Lensch, Hendrik P. A.; Goesele, Michael; M¨uller, Gero; Karol Myszkowski and Vlastimil HavranOne important problem in photorealistic or predictive rendering nowadays is to realistically model the light interaction with objects. Measurements can capture the reflection properties of real world surface, i.e., they are one way of obtaining realistic reflection properties. For arbitrary (non-fluorescent, non-phosphorescent) materials, the reflection properties can be described by the 8D reflectance field of the surface, also called BSSRDF. Since densely sampling an 8D function is currently not practical various acquisition methods have been proposed which reduce the number of dimensions by restricting the viewing or relighting capabilities of the captured data sets. In this tutorial we will mainly focus on three different approaches, the first allowing to reconstruct opaque surfaces from a very small set of input images, the second allows for arbitrary surfaces but under the assumption of distant light sources and the last which allows for relighting an arbitrary scene with arbitrary spatially varying light patterns. After a short introduction explaining some fundamental concepts regarding measuring and representing reflection properties, the basics of data acquisition with photographs will be addressed. The tutorial present the set of current state-of-the art algorithms for acquiring and modeling 3D objects. The tutorial investigates the strengths and limitations of each technique and sorts them by their complexity with regard to acquisition costs. Besides describing the theoretical contributions we will furthermore point out the practical issues when acquiring reflectance fields in order to help interested users to build and implement their own acquisition setup.Item Color Pages(The Eurographics Association, 2007) Arnold, David B.; Ferko, Andrej; David B. Arnold and Andrej FerkoColor PagesItem Computational Geometry Education for Computer Graphics Students(The Eurographics Association, 2007) Kolingerová, Ivana; Isabel Navazo and Petr FelkelThe paper surveysmain features of computational geometry and presents an argumentation that a course oriented to the applied computational geometry should be a part of computer graphics curriculum as it teaches effective algorithmicmethods and helps to develop an abstract thinking. A possible contents of the course and forms suitable and interesting for computer graphics students are discussed. The students feedback for such a course has been mostly positive.Item Computational Photography(The Eurographics Association, 2007) Raskar, Ramesh; Tumblin, Jack; Mohan, Ankit; Agrawal, Amit; Li, Yuanzen; Karol Myszkowski and Vlastimil HavranComputational photography combines plentiful computing, digital sensors, modern optics, actuators, probes and smart lights to escape the limitations of traditional film cameras and enables novel imaging applications. Unbounded dynamic range, variable focus, resolution, and depth of field, hints about shape, reflectance, and lighting, and new interactive forms of photos that are partly snapshots and partly videos are just some of the new applications found in Computational Photography. The computational techniques encompass methods from modification of imaging parameters during capture to sophisticated reconstructions from indirect measurements. We provide a practical guide to topics in image capture and manipulation methods for generating compelling pictures for computer graphics and for extracting scene properties for computer vision, with several examples. Many ideas in computational photography are still relatively new to digital artists and programmers and there is no upto- date reference text. A larger problem is that a multi-disciplinary field that combines ideas from computational methods and modern digital photography involves a steep learning curve. For example, photographers are not always familiar with advanced algorithms now emerging to capture high dynamic range images, but image processing researchers face difficulty in understanding the capture and noise issues in digital cameras. These topics, however, can be easily learned without extensive background. The goal of this presentation is to present both aspects in a compact form. The new capture methods include sophisticated sensors, electromechanical actuators and on-board processing. Examples include adaptation to sensed scene depth and illumination, taking multiple pictures by varying camera parameters or actively modifying the flash illumination parameters. A class of modern reconstruction methods is also emerging. The methods can achieve a photomontage by optimally fusing information from multiple images, improve signal to noise ratio and extract scene features such as depth edges. The presentation briefly reviews fundamental topics in digital imaging and then provides a practical guide to underlying techniques beyond image processing such as gradient domain operations, graph cuts, bilateral filters and optimizations. The participants learn about topics in image capture and manipulation methods for generating compelling pictures for computer graphics and for extracting scene properties for computer vision, with several examples. We hope to provide enough fundamentals to satisfy the technical specialist without intimidating the curious graphics researcher interested in recent advances in photography. The intended audience is photographers, digital artists, image processing programmers and vision researchers using or building applications for digital cameras or images. They will learn about camera fundamentals and powerful computational tools, along with many real world examples.Item Construction of Non-Blobby Surface from Particles(The Eurographics Association, 2007) Harada, Takahiro; Koshizuka, Seiichi; Kawaguchi, Yoichiro; Paolo Cignoni and Jiri SochorThis paper presents a method that can construct a surface with a thin region or sharp edges from particles. The surface is constructed in two stages. An implicit surface is generated by assigning a density distribution to each particle in the first step and then the surface constructed from the density distribution is changed to a surface with a thin region or sharp edges. Furthermore, the method can generate various kinds of surfaces because a surface is controlled by several parameters. Therefore, the present technique increases the range of expression of particle-based simulations. In this paper, some calculation results are presented and finally an application from the results of particle-based fluid simulation is discussed.Item Creating Interest in Computer Graphics by Teaching Game Development(The Eurographics Association, 2007) Amresh, Ashish; Karnick, Pushpak; Isabel Navazo and Petr FelkelThis paper describes our experiences in designing and implementing a junior/senior level undergraduate course in Game Programming at Arizona State University. We highlight the pedagogical methods employed during each of the three semesters that the class was offered. We compare our approach with established teaching methods and highlight the advantages of implementing our novel approach for teaching game development. We establish a strong connection between teaching game programming and computer graphics and show how an introductory game programming class can be an excellent way for getting junior and senior level undergraduate students excited about computer graphics.Item Cultural Heritage as a Vehicle for Basic Research in Computing Science: Pasteur's Quadrant and a Use-inspired Basic Research Agenda(The Eurographics Association, 2007) Arnold, David; David B. Arnold and Andrej FerkoDonald Stokes argued [Sto97] that for 50 years from the end of the second world war to the end of the 20th century there was an unhealthy taxonomy of research types which was formulated on a linear scale from pure to applied. The argument goes that the best research is only possible in environments which are free from contemplation of the potential uses to which results might be applied. In this paper current research challenges in the application of ICTs to cultural heritage information are reviewed in order to consider where these applications-linked needs require solutions that will advance the understanding of computational principles and help to develop new basic understanding in computer science, including shape manipulation and other aspects of importance in computer graphics and virtual environments. The paper draws extensively on the recent published EPOCH research agenda [AG07] for illustrations of the types of research which are required for the Cultural Heritage sector and the relationship between these and basic research challenges in Computing Science.Item A Discussion of the CGE06 Workshop Report(The Eurographics Association, 2007) Cunningham, Moderator: Steve; Isabel Navazo and Petr FelkelThe CGE06 workshop, held after the EG06 conference in Vienna, recommended a structure for first cycle an and second cycle education in computer graphics. The workshop report is online at d http://education.siggraph.org/conferences/eurographics/2006/cge2006. This discussion will present an overview of the recommended structure by four European workshop participa participants. They will present their views on the workshop recommendations and will discuss any nts. steps that have been taken to implement them in their own or in other universities.Item An E-Learning Course on Scientific Visualization(The Eurographics Association, 2007) Taras, Christiane; Rotard, Martin; Ertl, Thomas; Isabel Navazo and Petr FelkelIn this paper we present an e-learning course on scientific visualization. Based on over ten years of teaching experiences in this field, we have created a multimedia online course which we use as additional material for our lecture. The course will be made publicly available so that not only our students but all people interested in the field of scientific visualization can benefit from the materials we have prepared. In the course important visualization techniques and algorithms are discussed. The main goal is to lay the foundamentals for future specialists and researchers in the field of scientific visualization.Item EG 2007 Course on Populating Virtual Environments with Crowds(The Eurographics Association, 2007) Thalmann, Daniel; O'Sullivan, Carol; Yersin, Barbara; Maïm, Jonathan; McDonnell, Rachel; Karol Myszkowski and Vlastimil HavranFor many years, it was a challenge to produce realistic virtual crowds for special effects in movies. Now, there is a new challenge: the production of real-time autonomous Virtual Crowds. Real-time crowds are necessary for games, VR systems for training and simulation and crowds in Augmented Reality applications. Autonomy is the only way to create believable crowds reacting to events in real-time. This course will present state-of-the-art techniques and methods.Item Enforcing Scene Constraints in Single View Reconstruction(The Eurographics Association, 2007) Lourakis, Manolis; Argyros, Antonis; Paolo Cignoni and Jiri SochorThree-dimensional reconstruction from a single view is an under-constrained process that relies critically upon the availability of prior knowledge about the imaged scene. This knowledge is assumed to be supplied by a user in the form of geometric constraints such as coplanarity, parallelism, perpendicularity, etc, based on his/her interpretation of the scene. In the presence of noise, however, most of the existing methods yield reconstructions that only approximately satisfy the supplied geometric constraints. This paper proposes a novel single view reconstruction method that provides reconstructions which exactly satisfy all user-supplied constraints. This is achieved by first obtaining a preliminary reconstruction and then refining it in an extendable, constrained optimization framework.