24-Issue 2

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https://diglib.eg.org/handle/10.2312/120

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    Anti-Aliased Lines Using Run-Masks
    (The Eurographics Association and Blackwell Publishing Ltd., 2005) Diakopoulos, Nicholas A.; Stephenson, Peter D.
    In recent work, a set of line digitization algorithms based on the hierarchy of runs in the digital line has unified and generalized the iterative line-drawing algorithms used in computer graphics. In this paper, the additional structural information generated by these algorithms is leveraged to describe a run-based approach to draw anti-aliased line segments in which anti-aliased run-masks are substituted for the individual run lengths as the line is being drawn. The run-masks are precomputed using a prefiltering technique such that one or more run-masks are defined for each of the one or two possible run lengths that occur in the line. The run-masks can be defined for any order or level of the hierarchy of runs in the digital line and the technique is illustrated using runs of pixels. Comparing the use of run-masks to applying the prefiltering technique for each pixel in the line, a line of similar visual quality can be produced more efficiently. We place no restrictions on the placement of the end points of the line, which may reside anywhere on the two-dimensional plane.
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    A Data-Driven Approach for Real-Time Clothes Simulation
    (The Eurographics Association and Blackwell Publishing Ltd., 2005) Cordier, Frederic; Magnenat-Thalmann, Nadia
    A data-driven approach for the real-time processing of clothes, particularly suitable for simulating dresses worn by virtual characters, is proposed. It starts, prior to real-time simulation, by analyzing cloth behavior in relation to the underlying skeleton movement from a presimulated sequence of the cloth obtained using any high-quality off-line simulators. The idea is to use this analysis to find an optimal combination of physics-based simulation and geometric approximation of the simulator; potentially colliding regions are defined on the cloth such that they will hold true for the skeleton movement that closely matches that of presimulated sequence. At runtime, using these analyses, our simulation process provides both visually pleasing results and performance, as long as the motion of the character remains sufficiently close to the original sequence used for the precomputation.The key contributions of this paper are (1) efficient collision handling that prunes out potentially colliding objects by using the off-line simulation sequence as examples; (2) data-driven fix-up process for the coarse mesh simulation that deduces the gross behavior of the cloth; and (3) geometric approximation of the fine mesh deformation, responsible for details in the shape of the cloth such as wrinkles.
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    Dual Marching Cubes: Primal Contouring of Dual Grids
    (The Eurographics Association and Blackwell Publishing Ltd., 2005) Schaefer, Scott; Warren, Joe
    We present a method for contouring an implicit function using a grid topologically dual to structured grids such as octrees. By aligning the vertices of the dual grid with the features of the implicit function, we are able to reproduce thin features of the extracted surface without excessive subdivision required by methods such as Marching Cubes or Dual Contouring. Dual Marching Cubes produces a crack-free, adaptive polygonalization of the surface that reproduces sharp features. Our approach maintains the advantage of using structured grids for operations such as CSG while being able to conform to the relevant features of the implicit function yielding much sparser polygonalizations than has been possible using structured grids.
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    Editorial
    (The Eurographics Association and Blackwell Publishing Ltd., 2005) Duke, David; Scopigno, Roberto
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    Glare Generation Based on Wave Optics
    (The Eurographics Association and Blackwell Publishing Ltd., 2005) Kakimoto, Masanori; Matsuoka, Kaoru; Nishita, Tomoyuki; Naemura, Takeshi; Harashima, Hiroshi
    This paper proposes a novel and general method of glare generation based on wave optics. A glare image is regarded as a result of Fraunhofer diffraction, which is equivalent to a 2D Fourier transform of the image of given apertures or obstacles. In conventional methods, the shapes of glare images are categorized according to their source apertures, such as pupils and eyelashes and their basic shapes (e.g. halos, coronas, or radial streaks) are manually generated as templates, mainly based on statistical observation. Realistic variations of these basic shapes often depend on the use of random numbers. Our proposed method computes glare images fully automatically from aperture images and can be applied universally to all kinds of apertures, including camera diaphragms. It can handle dynamic changes in the position of the aperture relative to the light source, which enables subtle movement or rotation of glare streaks. Spectra can also be simulated in the glare, since the intensity of diffraction depends on the wavelength of light. The resulting glare image is superimposed onto a given computer-generated image containing high-intensity light sources or reflections, aligning the center of the glare image to the high-intensity areas. Our method is implemented as a multipass rendering software. By precomputing the dynamic glare image set and putting it into texture memory, the software runs at an interactive rate.
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    Modeling Color Properties of Tiled Displays
    (The Eurographics Association and Blackwell Publishing Ltd., 2005) Majumder, Aditi; Gopi, M.
    The concept of tiled displays can be successful only if such displays are made to look like a single display perceptually. The two issues that need to be solved to achieve this goal are geometric correction and color seamlessness of images spanning across tiles. Geometric correction algorithms borrow pin-hole camera models to model projector display geometry. In this paper, we introduce an abstract modeling function that describes the color seen by a viewer when displayed by a display device.Though this function can be used to model color displayed by any common display device, in this paper, we use it to model color in multiprojector display systems. We use the model to explain the reasons for different types of color variations in a multiprojector display, to compare different color correction algorithms, and to derive such algorithms directly from the model.
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    RenderBots-Multi-Agent Systems for Direct Image Generation
    (The Eurographics Association and Blackwell Publishing Ltd., 2005) Schlechtweg, Stefan; Germer, Tobias; Strothotte, Thomas
    The term stroke-based rendering collectively describes techniques where images are generated from elements that are usually larger than a pixel. These techniques lend themselves well for rendering artistic styles such as stippling and hatching. This paper presents a novel approach for stroke-based rendering that exploits multi-agent systems. RenderBots are individual agents each of which in general represents one stroke. They form a multi-agent system and undergo a simulation to distribute themselves in the environment. The environment consists of a source image and possibly additional G-buffers. The final image is created when the simulation is finished by having each RenderBot execute its painting function. RenderBot classes differ in their physical behavior as well as their way of painting so that different styles can be created in a very flexible way.
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    Survey of Real-Time Rendering Techniques for Crowds
    (The Eurographics Association and Blackwell Publishing Ltd., 2005) Ryder, G.; Day, A. M.
    Real-time rendering of photo-realistic humans is considerably outside the scope of current consumer-level computer hardware. There are many techniques, which attempt to bridge the gap between what is desired and what is possible. This paper aims to give an overview of the techniques designed to alter the complexity of the model s geometry (level of detail), or replace it with a flat image (visual impostor) and to improve the lighting model (lighting and shadows). Recent years have shown a boom in the power and availability of consumer-level programmable graphics processors, thus techniques that make use of these features are coming to the forefront.
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    Visual Supercomputing: Technologies, Applications and Challenges
    (The Eurographics Association and Blackwell Publishing Ltd., 2005) Brodlie, Ken; Brooke, John; Chen, Min; Chisnall, David; Fewings, Ade; Hughes, Chris; John, Nigel W.; Jones, Mark W.; Riding, Mark; Roard, Nicolas
    If we were to have a Grid infrastructure for visualization, what technologies would be needed to build such an infrastructure, what kind of applications would benefit from it, and what challenges are we facing in order to accomplish this goal? In this survey paper, we make use of the term visual supercomputing to encapsulate a subject domain concerning the infrastructural technology for visualization. We consider a broad range of scientific and technological advances in computer graphics and visualization, which are relevant to visual supercomputing. We identify the state-of-the-art technologies that have prepared us for building such an infrastructure. We examine a collection of applications that would benefit enormously from such an infrastructure, and discuss their technical requirements. We propose a set of challenges that may guide our strategic efforts in the coming years.