EG2003

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Certosa virtual museum: a dynamic multilevel desktop VR application
(Eurographics Association, 2003) Calori, L.; Diamanti, T.; Guidazzoli, A.; Liguori, M. C.; Mauri, M. A.; Valentini, L.
Starting from the exigencies of restoration, safeguard and promotion set by Bologna City Council for its Museum of the Certosa Cemetery, a multilevel application has been developed. Its main features are dynamic generation of models, interaction with objects, link to relational multimedia database, DTM and a friendly, computer games like interface. The outcome is a flexible product, both from a technological point of view – it can be experienced on low cost platforms as well as in HI End systems - and for the possible kind of fruition, that can involve several different groups of users.
A Spatial Representation for Ray-Scene Intersection Test Improvement in Complex Scenes
(Eurographics Association, 2003) Revelles, J.; Aguilera, N.; Aguado, J.; Lastra, M.; Garcia, R.; Montes, R.
We present a spatial representation based on a hierarchical structure using the well-known spatial indexing structure called octree. There are very useful spatial representations for scenes whose objects can be distributed in clusters and here we present a new one. In order to prove its benefits, several results are shown in scenes using a photom tracing algorithm to compute the global illumination based on photon map. These results show that the hierarchy of octrees becomes a good choice to improve the performance when compare to other strategies such as octrees and hierarchy of uniform grids3.
Inelastic Scattering and Participating Media.Application to the ocean
(Eurographics Association, 2003) Cerezo, Eva; Seron, Francisco J.
A system, developed to treat general participating media, is generalized to make it capable of considering volumetric inelastic processes such as fluorescence. The system is based on the discrete ordinates method, and can treat complex participating medium such as natural waters. It can deal with highly-peaked anisotropic phase functions and can handle the spectral behavior of the medium's characteristic parameters.The system is applied to the study of fluorescence, the most common inelastic effect in natural waters.
Generation of Radiosity Texture Atlas for Realistic Real-Time Rendering
(Eurographics Association, 2003) Ray, Nicolas; Ulysse, Jean-Christophe; Cavin, Xavier; Levy, Bruno
Radiosity methods are a both physically correct and efficient way to compute the global illumination giving the visual atmosphere to a 3D scene. In this paper, we present a new approach to optimizing the visualization of meshed models illuminated using these methods. Our approach is based on a texture atlas, which makes it possible to store the global illumination in a set of textures, that can be mapped in real-time onto the model by the graphics hardware. Our contribution is a new robust atlas generation method well adapted to the visualization of illuminated complex meshed models, and based on a tight cooperation between the segmentation and the parameterization algorithms. In our segmentation method, the combinatorial information of the mesh is systematically preferred over the geometry whenever possible, which makes the algorithm both simpler and more robust. Large industrial models with complex topologies and poor mesh qualities can be efficiently processed. The paper concludes with some results, showing our method applied to architectural and car design industry models, and demonstrating that it both speeds up the visualization and is easy to integrate into existing advanced rendering software.
Goniometric Diagram Mapping for Hemisphere
(Eurographics Association, 2003) Havran, Vlastimil; Dmitriev, Kirill; Seidel, Hans-Peter
Describing the light intensity over the hemisphere using a goniometric diagram is a common practice in the lighting industry and is prescribed for instance by IESNA (Illuminating Engineering Society of North America) standards. Goniometric diagram specifies the spatial distribution of the emitted power via a hemispherical surface subdivided by meridians and parallels. Similar tabulated representations are extensively used for complex bidirectional refiectance distribution functions (BRDF) that are difficult to approximate with analytical models. We present an approximative bicontinuous mapping from the unit square to a goniometric diagram on the hemisphere. This mapping has low distortion and the error of the approximation is low. The proposed mapping algorithm is obtained as a composition of four mappings. We outline its use for importance sampling of light sources described by goniometric diagrams and for the representation of BRDF.
Extending the Immediate Buckling Model to Triangular Meshes for Simulating Complex Clothes
(Eurographics Association, 2003) Choi, Kwang-Jin; Ko, Hyeong-Seok
The immediate buckling model is an essential element for simulating realistic cloth animations without introducing buckling instability. The original model is restricted to structured regular quad meshes, by which its use is severely limited. This paper extends the immediate buckling model from its original formulation in terms of regular quad meshes to irregular triangular meshes, thereby significantly increasing the applicability of the technique. Using a model that included cloth-specific buckling and anisotropy, we produced realistic animations of quite complex clothes.
Preface
(Eurographics Association, 2003)
A Precise Approach Calibrated by Experimental Data to Make an Artificial Impulse
(Eurographics Association, 2003) Iguchi, Toshiko; Kodama, Tetsuya; Noborio, Hiroshi
Baraffs and Mirtichs approaches are well known so as to generate force and impulsive force artificially at collision between rigid bodies. However, both cannot be unfortunately applied for a practical use such as complex dynamic animation and simple haptic rendering. The reason is as follows: Baraff s approach deals with many forces at multiple contacts, but does not always calculate a solution under static and dynamic frictions. Moreover, since almost natural contact phenomena should be operated by not force but impulse (a sequence of forces) supervised by time, his approach cannot manage such practical aspects. On the other hand, Mirtichs approach completely neglects time, e.g., the interval of collision, and consequently make only an impulsive force (does not generate a true impulse as force distribution). Consequently, they cannot be applicable to dynamic animation including simultaneous multiple contacts and haptic rendering. For this reason, we propose a new approach based upon integration of an arbitrarily chosen force distribution over a finite time interval by time. Also, we discuss a new method to calibrate completely the force distribution and uncertain parameters required in our new approach. By the deep calibration, the accuracy of linear tangential and angular impulses in our approach is superior to that of these impulsive forces in Mirtichs approach.
Parametric Foveation for Progressive Texture and Model Transmission
(Eurographics Association, 2003) Cheng, Irene; Basu, Anup; Pan, Yixin
Spatially varying sensing (foveation) has been used in many different areas of Computer Vision, such as image compression and video teleconferencing and in perceptually driven Level of Detail (LOD) representations in graphics. In this work, we show that foveation is advantageous for interactive mesh and texture transmission in online 3D applications. Unlike traditional mesh representations where all 3D vertices need to be transmitted, we only need to transmit a collection of points-of-interest (foveae) and information on only one (rather than three) axis. Thereby, we can achieve a threefold reduction in the amount of data that needs to be transmitted to represent a new 3D model. Our research differs from level of detail (LOD) based approaches using perceptually driven simplification in that (i) the mesh and texture resolutions vary smoothly and continuously in our approach compared to distinct levels of details in adjoining regions in other foveated or multiresolution LOD based methods; and (ii) the approach works for an integrated foveated texture and mesh representation. The current implementation extends our past research in image and video compression [1] and is restricted to regular grid mesh representation produced by 3D scanners.
Non-Photorealistic Rendering
(Eurographics Association, 2003) Eißele, Mike
• Focus of this talk – Silhouette rendering – Cartoon shading – Hatching – Charcoal rendering – Image-space filter operations – Dither screens
Real Numbers, Real Images
(Eurographics Association, 2003) Ward, Greg
This tutorial develops the thesis that the real world is best represented by real numbers, which are approximated by floating point values in the computer. As the floating point unit (FPU) continues to accelerate, outpacing the arithmetic logic unit (ALU), it makes more and more sense to do our graphics calculations entirely with real numbers. We even see the mainstream changing in this direction with the introduction of floating point frame buffers in a new generation of graphics cards, such as NVidia’s GeForce FX.
Uncertainty Visualization Methods in Isosurface Rendering
(Eurographics Association, 2003) Rhodes, Philip J.; Laramee, Robert S.; Bergeron, R. Daniel; Sparr, Ted M.
We describe two techniques for rendering isosurfaces in multiresolution volume data such that the uncertainty (error) in the data is shown in the resulting visualization. In general the visualization of uncertainty in data is difficult, but the nature of isosurface rendering makes it amenable to an effective solution. In addition to showing the error in the data used to generate the isosurface, we also show the value of an additional data variate on the isosurface. The results combine multiresolution and uncertainty visualization techniques into a hybrid approach. Our technique is applied to multiresolution examples from the medical domain.
Image-based Extraction of Material Reflectance Properties of a 3D Rigid Object
(Eurographics Association, 2003) Erdem, M. Erkut; Erdem, I. Aykut; Atalay, Volkan
In this study, we concentrate on the extraction of reflectance properties of a 3D rigid object from its 2D images and the other aim of this work is rendering the object in real-time with photorealistic quality in varying illumination conditions. The reflectance property of the object is decomposed in diffuse and specular components. While the diffuse components are stored in a global texture, the specularity of the object is represented by a single Bidirectional Reflectance Distribution Function (BRDF). In the rendering phase, these two components are combined to obtain the behavior of the real surface property of the object.
Transformation of a Boys Surface into a Steiners Surface and torus eversion
(Eurographics Association, 2003) Langer, M.
The part 1 of the video shows a Boy s surface and a Steiner s Roman surface which are difficult to visualize without computer 3d graphics and demonstrates a continuous topological transformation between them. The part 2 of the video shows step by step how a two-dimensional torus with a hole can be turned inside out in R3 by a continuous topological operation without self-intersections. The torus without a disk, Boy s surface and Steiner s Roman surface are constructed as photorealistic two-sided and front-back coloured 3d objects.
Interactive Learning of Computer Graphics Algorithms
(Eurographics Association, 2003) Pan, Zhigeng; Lun, Hung Pak; Gao, Rong
Nowadays, computer graphics course is usually taught with traditional teaching methodologies and tools, which has its own limitations. In this paper, we present an online interactive computer graphics tutorial. The practical part of the tutorial consists of example programs on the computer in which the users can test the theoretical concepts and generate their own experiences. The integration of the different theoretical and practical parts of the course is realized through a common Web-based interface to the system. The main objective is to allow the users to learn and practice with the algorithms of computer graphics. Two versions of the system in Chinese and English language are implemented.
An Interaction View on Information Visualization
(Eurographics Association, 2003) Kosara, Robert; Hauser, Helwig; Gresh, Donna L.
Information Visualization (InfoVis) encompasses techniques of visualization that deal primarily with abstract data, that is, data for which the user has no preconceived mental model. This is in contrast to, for example, volume or flow data. For this reason, interaction is particularly important in InfoVis: for exploration, analysis, and presentation of data. Interaction allows the user to implicitly form mental models of the correlations and relationships in the data, through recognition of patterns, marking or focusing in on those patterns, forming mental hypotheses and testing them, and so on. Some interaction techniques are very specific to InfoVis (even though they can be and are applied to other areas as well), such as Focus+Context and Linking+Brushing. This paper surveys InfoVis techniques with an orientation toward interaction aspects, rather than data model or display dimension. It also tries to put the work into perspective by including aspects such as user studies for the evaluation of methods.
Advanced Shading Techniques
(Eurographics Association, 2003) Diepstraten, Joachim
Focus of this talk: • Per-pixel point light Blinn-Phong lighting • Per-pixel realistic metal-BRDF • Per-pixel anisotropic lighting • Procedural textures • Different reflection/environment mapping techniques • “Faked“ translucency
Distributed and Collaborative Visualization
(Eurographics Association, 2003) Brodlie, Ken; Duce, David; Gallop, Julian; Walton, Jeremy; Wood, Jason
Visualization is widely used in science, medicine and engineering. It can convey insight into phenomena that are well-understood, or display new data in order to uncover novel patterns of meaning. Visualization is a powerful tool in presentations (lectures, seminars, papers etc) and in discussions between colleagues. As such, it is an essentially collaborative activity. In this area, there is also a growth in the use of video conferencing to facilitate meetings between participants in geographically separate locations. This includes both specialized facilities (video conference rooms including Access Grid) and desktop video conferencing using the Internet and multicast communications. Distributed visualization addresses a number of resource allocation problems, including the location of processing close to data for the minimisation of data traffic. The advent of the Grid Computing paradigm and the link to Web Services provides fresh challenges and opportunities for distributed visualization - including the close coupling of simulations and visualizations in a steering environment. Distributed collaborative visualization aims to enhance the video conferencing environment (usually on the desktop) with access to visualization facilities. At the most basic level, pre-generated visualizations may be shared through a shared whiteboard tool. Richer approaches enable users to share control of the visualization method and its parameters. In one approach, a single visualization application is shared amongst a group of users; in another approach, the visualization dataflow paradigm is extended in order to allow sharing of visualization data between collaborators. Component middleware provides a framework for describing and assembling distributed collaborative visualization applications. The AccessGrid allows group-group collaboration, rather than just person-person, and generally offers a rich environment for collaboration - we look at ways of integrating current visualization systems into this new type of environment. XML has made a significant impact in many areas of computing, from e-business to mathematics. It is being increasingly used as the middle tier of client-server interfaces where its power and flexibility makes it ideal for middleware (for example, SOAP and related Web Services developments in W3C). Current developments in Grid middleware are based on an enhancement to Web Services (the Open Grid Services Architecture - OGSA). This STAR reviews the state of the art in these areas, draws out common threads in these diverse approaches and looks at strengths, weaknesses and opportunities for further development in this field.
Real-Time Simulation of Flexible Materials in Avango Virtual Environment Framework
(Eurographics Association, 2003) Klimenko, Stanislav; Nikitina, Lialia; Nikitin, Igor
his paper describes a system for real-time simulation of linear elastic deformations of volumetric objects in Virtual Environments, implemented in Avango VE Framework 1. The approach makes use of the methods of Finite and Boundary Elements and precomputed Greens functions, and supports real-time interactive deformations of large elastic models, containing more than 10,000 volumetric nodes, at the graphics update rate 85fps.
Realtime Ray Tracing and its use for Interactive Global Illumination
(Eurographics Association, 2003) Wald, Ingo; Purcell, Timothy J.; Schmittler, Jörg; Benthin, Carsten; Slusallek, Philipp
Research on realtime ray tracing has recently made tremendous advances. Algorithmic improvements together with optimized software implementations already allow for interactive frame rates even on a single desktop PC. Furthermore, recent research has demonstrated several options for realizing realtime ray tracing on different hardware platforms, e.g. via streaming computation on modern graphics processors (GPUs) or via the use of dedicated ray tracing chips. Together, these developments indicate that realtime ray tracing might indeed become a reality and widely available in the near future. As most of todays global illumination algorithms heavily rely on ray tracing, this availability of fast ray tracing technology creates the potential to finally compute even global illumination – the physically correct simulation of light transport – at interactive rates. In this STAR, we will first cover the different research activities for realizing realtime ray tracing on different hardware architectures – ranging from shared memory systems, over PC clusters, programmable GPUs, to custom ray tracing hardware. Based on this overview, we discuss some of the advanced issues, such as support for dynamic scenes and designs for a suitable ray tracing API. The third part of this STAR then builds on top of these techniques by presenting algorithms for interactive global illumination in complex and dynamic scenes that may contain large numbers of light sources. We believe that the improved quality and the increased realism that global illumination adds to interactive environments makes it a potential “killer application” for future 3D graphics.

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