EG2004

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https://diglib.eg.org/handle/10.2312/243

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A Web-Based Multimedia Virtual Reality Environment for E-Learning
(Eurographics Association, 2004) McArdle, Gavin; Monahan, Teresa; Bertolotto, Michela; Mangina, Eleni; M. Alexa and E. Galin
The past decade has seen major advances in the availability of broadband computer access. With this everincreasing connection speed and improved Internet performance more and more web-based applications are becoming available. More complex graphics and multi-media can now be transmitted over the Internet relatively quickly in real-time and with little delay. One area where web-based applications have proved very successful in the past, is within the e-learning paradigm. Traditionally, online learning applications have used a text-based asynchronous format to deliver learning material to end-users. While this has proved successful, it is recognised that the social and collaborative experience plays an important role in education. This paper describes CLEVR, a Collaborative Learning Environment with Virtual Reality. CLEV-R is a web-based application, that takes advantage of an increased connection speed to deliver a real-time Virtual Reality (VR) environment where learning material is augmented through the use of multi-media. The environment mimics the real world where users, represented by avatars, take on various roles in the VR world.
Advanced Virtual Medicine: Techniques and Applications for Medicine Oriented Computer Graphics
(Eurographics Association, 2004) Delingette, H.; Linney, A.; Magnenat-Thalmann, N.; Wu, Yin; Bartz, D.; Hauth, M.; Mueller, K.
The course will introduce techniques of modelling and simulating human tissue for medical applications. The course includes basic and advanced techniques of segmentation, registration, reconstruction and motion simulation in medical applications from disease detection to surgery simulation and surgery in virtual reality. This tutorial introduces various methods along with concrete clinic cases and present examples to convert research work to commercial applications.
Enriching Animation Databases
(Eurographics Association, 2004) Ahmed, Amr; Mokhtarian, Farzin; Hilton, Adrian; M. Alexa and E. Galin
The paper presents a framework for enriching an existing basic animation databse by modifying existing motions to generate a variety of new motions. Intuitively controlled motion varities are generated on demand which reduces the storage requirements, avoids recapturing missing variations, and provides greater flexibility and utilisation of existing clips. An improved root-trajectory blending is introduced that overcomes the limitations of ordinary blending (including flipping of the root trajectory when blending motions of opposite path-curvature or opposite directions). A novel synchronised mirror technique is also introduced.
Adaptive Brush Stroke Generation for Painterly Rendering
(Eurographics Association, 2004) Park ChungAng, Youngsup; Yoon, Kyunghyun; M. Alexa and E. Galin
We propose adaptive brush stroke generation for source images, using reference data. Colors used are formed by actual palette colors from artists. To create the palette, we have referred mostly to colors used in Van Gogh’s works and determined the color of brush strokes by transferring it to the most similar one, through comparing colors used in source images and the palette colors. Also, by referring to the edge orientation of source images, we have applied a brush stroke orientation that surrounds the edges. The sizes were determined depending on the different sizes of the objects from wide to narrow brushes. Finally, we applied spline curve shapes. The brush strokes created in such method, were applied separately according to its segmented images, and composed after rendering.
A Real Time Light Probe
(Eurographics Association, 2004) Unger, Jonas; Gustavson, Stefan; Ollila, M.; Johannesson, M.; M. Alexa and E. Galin
We present a novel system capable of capturing high dynamic range (HDR) Light Probes at video speed. Each Light Probe frame is built from an individual full set of exposures, all of which are captured within the frame time. The exposures are processed and assembled into a mantissa-exponent representation image within the camera unit before output, and then streamed to a standard PC. As an example, the system is capable of capturing Light Probe Images with a resolution of 512x512 pixels using a set of 10 exposures covering 15 f-stops at a frame rate of up to 25 final HDR frames per second. The system is built around commercial special-purpose camera hardware with on-chip programmable image processing logic and tightly integrated frame buffer memory, and the algorithm is implemented as custom downloadable microcode software.
Virtual Clay for Direct Hand Manipulation
(Eurographics Association, 2004) Dewaele, Guillaume; Cani, Marie-Paule; M. Alexa and E. Galin
In order to make virtual modeling as easy as real clay manipulation, we describe a realtime virtual clay model, specially designed for direct hand manipulation. We build on a previous layered model for clay, extending it to handle local properties such as colour or fluidity, to deal with an arbitrary number of tools, and to capture twist effects due to rotating tools. The resulting clay model is the first step towards a more long term goal, namely direct interaction through video tracking of the user’s hands.
Frontier Sets: A Partitioning Scheme to Enable Scalable Virtual Environments
(Eurographics Association, 2004) Steed, Anthony; Angus, Cameron; M. Alexa and E. Galin
We present a new spatial partitioning scheme called frontier sets. Frontier sets build on the notion of a potentially visible set (PVS) [ARB90, TS91]. In a PVS a world is sub-divided into cells and for each cell all the other cells that can be seen are computed. Frontier sets represent regions of mutual invisibility. One frontier in a frontier set considers pairs of cells, A and B. It lists two sets of cells, FAB and FBA. From no cell in FAB is any cell in FBA visible and vice-versa. We have used frontier sets to investigate peer-to-peer networking schemes for networked virtual environments. Preliminary investigation of simulations within the Quake II game engine shows that frontiers have significant promise and may allow a new class of scalable peer-to-peer game infrastructures to emerge.
A Color Decomposition Method for Preserving Ukiyo-e Woodblocks
(Eurographics Association, 2004) Terai, Tomokazu; Mizuno, Shinji; Okada, Minoru; M. Alexa and E. Galin
In this paper we propose a color decomposition method for multicolor printing of watercolors including areas overlapping each print layer. Watercolors have an important feature that the observed colors are different on the printing order. The proposed method is based on a particle density model for expressing the effects of watercolors. The approach of this method is to solve an inverse problem, that is, determining a printed area corresponding to a watercolor from an observed image. Our purpose in this study is to estimate woodblocks from a woodblock print. The authors have already proposed a non-photorealistic rendering method to produce virtual woodblock prints. This approach can be utilized to Ukiyo-e. An Ukiyo-e print is created from several woodblocks with several watercolors, and has a mixing color expression similar to the effects of watercolor painting. The color decomposition method can be applied to produce virtual woodblocks in the virtual woodblock printing. The results of woodblock estimation will be utilized to preserve the techniques and prints of Ukiyo-e.
A Spectral Gamut-Mapping Environment with Rendering Parameter Feedback
(Eurographics Association, 2004) Bell, Ian E.; Alexander, Simon K.; M. Alexa and E. Galin
This paper proposes a prototypical environment for gamut mapping in spectral space. Images are rendered in terms of light and material parameters by a symbolic ray tracer, and the parameter ranges are adjusted, without re-rendering, to bring the image into the output device's spectral gamut. There is a growing disparity between the high dynamic range images produced by spectral renderers and the limitations of display gamuts and lowdimensional colour management standards. While in rendering tone mapping has helped compress luminance ranges, and in colour science 3D gamut mapping has helped compress chrominance ranges, only high-dimensional spectral methods will fully bridge the gap. This paper's environment for gamuts in spectral space is a step toward spectral gamut mapping, which we demonstrate by using the ray tracer to predict feasible ranges of rendering parameters for an in-gamut image. The environment can be easily extended to support interactive or automatic image correction, and more sophisticated rendering and gamut-mapping methods of arbitrary dimensionality.
Visual Model of Fire
(Eurographics Association, 2004) Pszczolkowska, Dorota; M. Alexa and E. Galin
This paper presents a fire model based on dynamic particle chains. The chains are shaped and moved by a varying velocity field and constitute a density field, which is rendered using the ray tracing method. What we want to present are some new ideas we added to those inspired by our great predecessors' works, as well as some interesting results one can get with their use.
Modeling clouds shape
(Eurographics Association, 2004) Bouthors, Antoine; Neyret, Fabrice; M. Alexa and E. Galin
We propose a model for representing the shape of cumulus clouds.We draw on several approaches that we combine and extend: We store a hierarchy of quasi-spherical particles (or blobs) living on top of each other. The shape of these particles is defined by an implicit field which deforms under the influence of neighbor particles. We define a set of shaders to simulate a volumetric appearance in the spirit of Gardner's textured ellipsoids, to make the shape appear continuous, and to account for dedicated shading effects. In this paper we deal only with the definition of the shape. However, we believe that this model is well suited to be integrated with particle animation and advanced rendering.
Uniform Sampling for Image-based Rendering Shiny Objects
(Eurographics Association, 2004) Gong, Minglun; Yang, Yee-Hong; M. Alexa and E. Galin
A novel sampling technique is presented, which can evenly sample all rays that pass through a rectangular surface. Different view directions are uniformly sampled based on the shape of a spiral. Projection positions are then sampled adaptively according to the view direction to provide a constant sampling rate. The experimental results show that our approach can faithfully represent shiny real objects with a reasonable number of samples.
Multi-resolution Modeling, Visualization and Streaming of Volume Meshes
(Eurographics Association, 2004) Cignoni, P.; De Floriani, L.; Lindstrom, P.; Pascucci, V.; Rossignac, J.; Silva, C.
Volume meshes are widely used in geometric modeling, object reconstruction, level set methods and accurate simulations of physical behaviors like deformable materials, objects under stress, fracture dynamics, optical effects and reproduction of smoke and fluid dynamics.
Packing Square Tiles into One Texture
(Eurographics Association, 2004) Decaudin, Philippe; Neyret, Fabrice; M. Alexa and E. Galin
This paper deals with the packing of square tiles of the same size into one texture. Texture size is constrained by the graphics hardware. In particular, width and height resolutions must be powers of two. To cover the whole texture and avoid space loss, common schemes pack a number of tiles that is a power of two. We show that numbers of tiles like 5, 13, 17, 25, 34 and others can also be reached without wasting memory. To achieve this, our scheme takes advantage of texture rotation and the wrapping capability of texture-addressing, which gives a torus topology to the texture space.
RenderWare: Speed up the 3D Application Production Pipeline
(Eurographics Association, 2004) Guilbert, Oskar
The presentation gives the big picture for Criterion Software and how the Renderware technology provided by Criterion is used in the game industry. RenderWare's applications-authoring frame work will then be presented.
Geometric Algebra and its Application to Computer Graphics
(Eurographics Association, 2004) Hildenbrand, Dietmar; Perwass, Christian; Dorst, Leo; Fontijne, Daniel
In this tutorial we will give an overview of Geometric Algebra and its application to computer graphics. First of all, we want to motivate the topic and give insights into some applications.
The Visualisation and Expression of Virtual 3DSurfaces Explored through Custom Developed Interactive Software, Optically Mixed Coloured Surface Contouring and Fine Art Printmaking
(Eurographics Association, 2004) Lee, Peter John; M. Alexa and E. Galin
This short presentation paper describes an exploration and the visualisation of virtual 3D compositions through custom developed software and fine art printmaking. The author, a trained and practising visual artist considers this innovative visualisation as an exploration into the newly emerging visual language of the computer in similar vein to some of the NPR artists. The comprehension of virtual 3D objects is achieved primarily through linear surface contouring. The colour of these 3D surfaces is created by components intrinsic to the contour structure culminating in optical colour mixtures. The custom software, developed by the author, facilitates the application of the surface contouring to imported pre-constructed 3D object’s surfaces, computing the contouring component configurations and dimensions. Fine art screen-prints are created from DIBs generated within the software from the colour layers comprising the surface contouring. The printed DIBs form monochrome positives that are available for the artist to edit at will, before or following the transfer to screen-print screens and printing in CMYK screen-printing inks. The entire process can be reiterated editing the composition’s coloured contouring using the software, the positives or even the screens themselves until a satisfactory aesthetic result is obtained
An Oriented Particle and Generalized Spring Model for Fast Prototyping Deformable Objects
(Eurographics Association, 2004) Jeong, Il-Kwon; Lee, Inho; M. Alexa and E. Galin
We present a new mass-spring system, in particular, by using an oriented particle and generalized spring model, which can be used for fast prototyping or animation of deformable objects. Conventional mass-spring system is widely used especially in cloth animation. However animating deformable objects such as a jelly cube requires extra diagonal springs in addition to structural springs in order to provide shear strain force and guarantee stability on the original shape formation. One has to use his a priori knowledge or trial-anderror method to construct a stable spring network for a given deformable object. This is due to the inherent one-dimensional nature of the conventional spring model. In order to overcome the difficulty in designing a spring network and make it possible to construct a stable network easily and intuitively, we propose an oriented particle and generalized spring model that reacts against bending and twisting force as well as stretching. By using our new mass-spring system, one can easily construct a spring network from a given geometric model. Moreover, one can animate one-dimensional flexible object such as a mobile as well as a thin twodimensional object with sharp folds or creases. In addition, we present an offsetting method for tweaking mass-spring system to have valuable properties that help animating deformable objects with various shapes.
Programming Graphics Hardware
(Eurographics Association, 2004) Zeller, Cyril; Fernando, Randy; Wloka, Matthias; Harris, Mark
The presentation gives the big picture for the entire tutorial. It introduces the notions and frameworks that will be revisited in more details during the following presentations: Overview of the tutorial. Real-time graphics concept. Graphics pipeline concept.How the graphics pipeline maps to the PC architecture (CPU <-> GPU). Controlling the GPU from the CPU: The driver and 3D API (OpenGL, Direct3D). Evolution of the PC graphics pipeline and 3D APIs through time from fixed function pipeline to today's programmable pipeline, with introduction to z-buffering, texturing, TnL, multi-texturing, anti-aliasing, vertex and pixel shaders. Review of real-time graphics applications.
Collision Detection for Deformable Objects
(Eurographics Association, 2004) Teschner, M.; Kimmerle, S.; Heidelberger, B.; Zachmann, G.; Raghupathi, L.; Fuhrmann, A.; Cani, M.-P.; Faure, F.; Magnenat-Thalmann, N.; Strasser, W.; Volino, P.
Interactive environments for dynamically deforming objects play an important role in surgery simulation and entertainment technology. These environments require fast deformable models and very efficient collision handling techniques. While collision detection for rigid bodies is well-investigated, collision detection for deformable objects introduces additional challenging problems. This paper focusses on these aspects and summarizes recent research in the area of deformable collision detection. Various approaches based on bounding volume hierarchies, distance fields, and spatial partitioning are discussed. Further, image-space techniques and stochastic methods are considered. Applications in cloth modeling and surgical simulation are presented.

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