EG2007
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Item ProbonoWorld: Educating the Mentally Handicapped in a Virtual Environment using Props on a Board(The Eurographics Association, 2007) Groenewegen, Saskia; Froehlich, Bernd; Huckauf, Anke; Heinz, Stefanie; Isabel Navazo and Petr FelkelProbonoWorld is a system that allows mentally handicapped persons to safely train real-world situations in a virtual learning environment. Our system is based on the idea of using a prop on a board as an intuitive input device. ProbonoWorld is an expandable virtual world which may include different tasks at several locations and even tasks spanning multiple locations, such as shopping at the supermarket and then preparing a meal at home. To enable navigation through different areas of the world as well as different floors and rooms inside a building we devised four navigation strategies which are controlled by a prop on a single drawing tablet. In collaboration with instructors at a special education school we constructed tasks which teach procedures from everyday life. These tasks focus on navigation through different rooms in combination with a two-dimensional card-sorting game which requires ordering different steps of a familiar task. The subsequent evaluation of our system indicated a wide acceptance by the users and showed promising learning results. Our system differs from existing approaches through the use of intuitive prop-based navigation in a realistic virtual world with a navigation strategy tailored to mentally handicapped people. Our user study indicates that ProbonoWorld is easy to understand and supports learning processes.Item State of the Art in Ray Tracing Animated Scenes(The Eurographics Association, 2007) Wald, Ingo; Mark, William R.; Günther, Johannes; Boulos, Solomon; Ize, Thiago; Hunt, Warren; Parker, Steven G.; Shirley, Peter; Dieter Schmalstieg and Jiri BittnerRay tracing has long been a method of choice for off-line rendering, but traditionally was too slow for interactive use. With faster hardware and algorithmic improvements this has recently changed, and real-time ray tracing is finally within reach. However, real-time capability also opens up new problems that do not exist in an off-line environment. In particular real-time ray tracing offers the opportunity to interactively ray trace moving/animated scene content. This presents a challenge to the data structures that have been developed for ray tracing over the past few decades. Spatial data structures crucial for fast ray tracing must be rebuilt or updated as the scene changes, and this can become a bottleneck for the speed of ray tracing. This bottleneck has received much recent attention by researchers that has resulted in a multitude of different algorithms, data structures, and strategies for handling animated scenes. The effectiveness of techniques for ray tracing dynamic scenes vary dramatically depending on details such as scene complexity, model structure, type of motion, and the coherency of the rays. Consequently, there is so far no approach that is best in all cases, and determining the best technique for a particular problem can be a challenge. In this STAR, we aim to survey the different approaches to ray tracing animated scenes, discussing their strengths and weaknesses, and their relationship to other approaches. The overall goal is to help the reader choose the best approach depending on the situation, and to expose promising areas where there is potential for algorithmic improvements.Item Towards the Virtual Physiological Human(The Eurographics Association, 2007) Magnenat-Thalmann, Nadia; Gilles, Benjamin; Delingette, Hervé; Giachetti, Andrea; Agus, Marco; Karol Myszkowski and Vlastimil HavranThe objective of this tutorial is to train students and researchers in the various domains involving the modelling and simulation of the human body for medical purposes. Human body representations have been used for centuries to help in understanding and documenting the shape and function of its compounding parts. Nowadays, medical acquisition devices especially medical scanners are able to produce a large amount of information, such as highresolution volumes, temporal sequences or functional images, more-and-more difficult to analyse and visualise. In other words, we measure much more than we understand. In this context, higher-level information such as anatomical and functional models is increasingly required to support diagnosis and treatment. Three levels of complexity can be distinguished (geometry, function and control) where modelling and simulation methods take place. In this tutorial, we will present the current research issues towards the patient-specific reconstruction of virtual models and their functional simulation. We will focus on the computer graphics aspects involved in medical modelling/ simulation: deformable model-based segmentation, mesh optimisation, data fusion, interactive mechanical simulation, cost-efficient visualisation, etc. Examples will be given in the musculoskeletal, cardiac and neurological domains. All speakers are partners of the EU project "3D Anatomical Human" led by MIRALab - University of Geneva.Item A Unified Interpolatory and Approximation sqrt-3 Subdivision Scheme(The Eurographics Association, 2007) Lin, Shujin; Luo, Xiaonan; Paolo Cignoni and Jiri SochorWe have found that there is a relationship between the cubic B-spline and four-point curve subdivision method. In the paper it is used to deduce interpolatory subdivision schemes from cubic B-spline based approximation subdivision schemes directly and construct unified schemes for compositing approximation and interpolatory subdivision. A new interpolatory p3 subdivision scheme and a interpolatory and approximation blended p3 subdivision scheme are created by this straightforward method. The former produces C1 limit surface and avoids the problem in the exsiting interpolatory p3 subdivision mask where the weight coefficients on extraordinary vertices can not be described by explicit formulation. The latter can be used to solve the "popping effect" problem when switching between meshes at different levels of resolution, provide the possibility to locally choose an interpolating variant of the conventionally approximating subdivision scheme, and give more flexibility for feature modeling. These are realized by only changing the value of a parameter. The method is thoroughly simple without needs of constructing and solving equations.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 Volumetric Normal Mapping in Rendering of Multivariate Volume Data(The Eurographics Association, 2007) Seipel, Stefan; Paolo Cignoni and Jiri SochorThe work presented in this paper introduces volumetric normal maps for producing visual structure in direct volume rendering (DVR) of 3D data for the purpose of visualizing multiple attributes in a 3D volume. We use volumetric normal maps to represent normal vector glyphs that are subsequently applied to warp the gradients in the primary volume data. This method is intended to visualize some secondary attribute in DVR. We demonstrate that our method can render visual structures in DVR without the need of explicit surface reconstruction and texturing.Item Color Pages(The Eurographics Association, 2007) Arnold, David B.; Ferko, Andrej; David B. Arnold and Andrej FerkoColor PagesItem 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 Shape Representations Based on Simplicial and Cell Complexes(The Eurographics Association, 2007) Floriani, L. De; Hui, A.; Dieter Schmalstieg and Jiri BittnerSimplicial and cell complexes are the most common way to discretize 3D shapes and two-, three and higherdimensional scalar fields. In this state-of-the-art report, we review, analyze and compare data structures for simplicial and cell complexes. We first classify such representations, based on the dimension of the complexes they can encode, into dimension-independent, and dimension-specific ones. We further classify the data structures in each group according to the basic types of topological entities they represent. We present a description of each data structure in terms of the entities and topological relations it encodes, and we evaluate it based on its expressive power, on its storage cost, on the efficiency in supporting navigation inside the complex (i.e., in retrieving topological relations not explicitly encoded in the data structure). We also discuss a decomposition approach to modeling non-manifold shapes, which has led to powerful and scalable representations.Item Preface and Table of Contents(The Eurographics Association, 2007) -; David B. Arnold and Andrej FerkoPreface and Table of ContentsItem Inverse Kinematics and Kinetics for Virtual Humanoids(The Eurographics Association, 2007) Boulic, Ronan; Kulpa, Richard; Karol Myszkowski and Vlastimil HavranThe present tutorial deals with the use of inverse kinematics and kinetics for postural adaptations of virtual hu- manoids to different kind of constraints. It first proposes an overview of the problematic of this thematic and then of the existing techniques. Then it technically describes two key approaches: the prioritized inverse kinematics for accurate and realistic adaptation and a CCD-like algorithm based on groups for fast and realistic adaptation of hundreds of characters in real-time.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 Shape Analysis for Augmented Topological Shape Descriptor(The Eurographics Association, 2007) Symonova, Olga; Amicis, Raffaele De; Paolo Cignoni and Jiri SochorIn this work we propose a scheme for analysis of the shape of a 3D model.We use Extended Reeb Graph to describe the topological structure of the model which we further enrich with extracted geometrical features. The nodes of the graph represent different components of the model, and we propose to analyze their shape separately. Shape characteristics such as taper/enlargement, average curvature, bending are revealed through tracing changes in cross sections of each shape component. Finally the topological structure together with the associated geometrical characteristics represents the shape descriptor of the 3D model.Item Virtual Agent Navigation in Open Spaces using Iterative Shrinking Polygons(The Eurographics Association, 2007) Haciomeroglu, Murat; Laycock, Robert; Day, Andy; Paolo Cignoni and Jiri SochorPopulating an urban environment with a virtual crowd provides a dynamic element to an otherwise static scene; bringing the virtual environment to life. One of the fundamental components governing the fidelity of the scene is the realistic simulation of the crowd behaviour. To create a believable crowd simulation one group of methods considers constructing a graph covering the space available to the virtual agents and subsequently performing path planning to allow the agents to navigate their environment by traversing the edges of the graph. To avoid computationally expensive path planning algorithms there exists a tradeoff between the number of edges in the graph and the amount of available space which an agent can visit. In order to alleviate this problem we propose to compute the straight skeleton to provide an initial covering of the environment. This is subsequently augmented using iterative shrinking polygons to generate additional edges in the larger open spaces. The technique developed requires limited knowledge of the urban environment, processes the relevant information automatically and is illustrated in this paper to control the behaviour of a virtual crowd in real time.Item Report of the CGE 06 Computer Graphics Education Workshop, Vienna, Austria, September 9, 2006(The Eurographics Association, 2007) Bourdin, Jean-Jacques; Cunningham, Steve; Fairn, Marta; Hansmann, Werner; Isabel Navazo and Petr FelkelIn order to include computer graphics in European university programme programmes in computer science, the computer graphics curriculum must be organised along lines that satisfy the Bologna requirements for cross cross-university transfers. This workshop suggests ways to organise courses so that a computer graphics programme can be as comprehensive in its scope as fits any particular university, have its curriculum be easily understood by others, and allow simple transferring into and out of its programme. The structure developed by this workshop is still in ou outline form, but it serves as a tline framework from which actual courses and textbooks can be developed to fill out a comprehensive Bachelors and Masters computer graphics curriculum.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 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 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 Tangible Heritage: Production of Astrolabes on a Laser Engraver(The Eurographics Association, 2007) Zotti, Georg; David B. Arnold and Andrej FerkoThe astrolabe, an analog computing device, used to be the iconic instrument of astronomers during the Middle Ages. It allowed a multitude of operations of practical astronomy which were otherwise cumbersome to perform in an epoch when mathematics had apparently almost been forgotten. Usually made from wood or sheet metal, a few hundred instruments, mostly from brass, survived until today and are valuable museum showpieces. This paper explains a procedural modelling approach for the construction of the classical kinds of astrolabes, which allows a wide variety of applications from plain explanatory illustrations to 3D models, and even the production of working physical astrolabes usable for public or classroom demonstrations.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.