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Item 12th Eurographics Symposium on Virtual Environments(The Eurographics Association and Blackwell Publishing Ltd, 2007) Hubbold, Roger; Jorge, Joaquim; Lin, MingItem 2nd EG workshop on Natural Phenomena September 5th, 2007 Vienna (Austria)(The Eurographics Association and Blackwell Publishing Ltd, 2007) Chiba, Norishige; Galin, EricItem Accelerating Refractive Rendering of Transparent Objects(The Eurographics Association and Blackwell Publishing Ltd, 2007) Hui, K. C.; Lee, A. H. C.; Lai, Y. H.In this paper, a technique is proposed for the rendering of transparent objects interactively using the method of refractive rendering. In the proposed technique, the refractive rendering algorithm is performed in two stages, namely the pre-computation stage and the shading stage. In the pre-computation stage, ray-traced information, including directions and positions of rays, are generated by a ray tracing process and are stored in a set of ray lists. In the shading stage, these data are retrieved from the ray lists for computing the shading of an object. Using the proposed technique, photorealistic image of transparent objects and gemstones with various cuttings, material properties, lighting and background can be rendered interactively. By combining the refractive rendering technique with conventional shading techniques, jewelry and crystal designs can be rendered at a much higher speed comparing with conventional ray tracing techniques.Item Accurate Depth of Field Simulation in Real Time(The Eurographics Association and Blackwell Publishing Ltd, 2007) Zhou, Tianshu; Chen, Jim X.; Pullen, MarkWe present a new post processing method of simulating depth of field based on accurate calculations of circles of confusion. Compared to previous work, our method derives actual scene depth information directly from the existing depth buffer, requires no specialized rendering passes, and allows easy integration into existing rendering applications. Our implementation uses an adaptive, two-pass filter, producing a high quality depth of field effect that can be executed entirely on the GPU, taking advantage of the parallelism of modern graphics cards and permitting real time performance when applied to large numbers of pixels.Item CGForum 2007 Cover Image Trillion Triangle Terrain by Andreas Dietrich, Gerd Marmitt and Philipp Slusallek(The Eurographics Association and Blackwell Publishing Ltd, 2007)Item Editorial(The Eurographics Association and Blackwell Publishing Ltd, 2007) Duke, David; Scopigno, RobertoItem Effective Derivation of Similarity Transformations for Implicit Laplacian Mesh Editing(The Eurographics Association and Blackwell Publishing Ltd, 2007) Fu, Hongbo; Kin-Chung Au, Oscar; Tai, Chiew-LanLaplacian coordinates as a local shape descriptor have been employed in mesh editing. As they are encoded in the global coordinate system, they need to be transformed locally to reflect the changed local features of the deformed surface. We present a novel implicit Laplacian editing framework which is linear and effectively captures local rotation information during editing. Directly representing rotation with respect to vertex positions in 3D space leads to a nonlinear system. Instead, we first compute the affine transformations implicitly defined for all the Laplacian coordinates by solving a large sparse linear system, and then extract the rotation and uniform scaling information from each solved affine transformation. Unlike existing differential-based mesh editing techniques, our method produces visually pleasing deformation results under large angle rotations or big-scale translations of handles. Additionally, to demonstrate the advantage of our editing framework, we introduce a new intuitive editing technique, called configuration-independent merging, which produces the same merging result independent of the relative position, orientation, scale of input meshes.Item EUROGRAPHICS 2006 4 - 8 September, 2006 Vienna, Austria(The Eurographics Association and Blackwell Publishing Ltd, 2007) Purgathofer, WernerItem Eurographics Fellow(The Eurographics Association and Blackwell Publishing Ltd, 2007)Item Eurographics Honorary Fellowship(The Eurographics Association and Blackwell Publishing Ltd, 2007)Item Eurographics Honorary Fellowship(The Eurographics Association and Blackwell Publishing Ltd, 2007)Item A framework for quad/triangle subdivision surface fitting: Application to mechanical objects(The Eurographics Association and Blackwell Publishing Ltd, 2007) Lavoue, Guillaume; Dupont, Florent; Baskurt, AtillaIn this paper we present a new framework for subdivision surface approximation of three-dimensional models represented by polygonal meshes. Our approach, particularly suited for mechanical or Computer Aided Design (CAD) parts, produces a mixed quadrangle-triangle control mesh, optimized in terms of face and vertex numbers while remaining independent of the connectivity of the input mesh. Our algorithm begins with a decomposition of the object into surface patches. The main idea is to approximate the region boundaries first and then the interior data. Thus, for each patch, a first step approximates the boundaries with subdivision curves (associated with control polygons) and creates an initial subdivision surface by linking the boundary control points with respect to the lines of curvature of the target surface. Then, a second step optimizes the initial subdivision surface by iteratively moving control points and enriching regions according to the error distribution. The final control mesh defining the whole model is then created assembling every local subdivision control meshes. This control polyhedron is much more compact than the original mesh and visually represents the same shape after several subdivision steps, hence it is particularly suitable for compression and visualization tasks. Experiments conducted on several mechanical models have proven the coherency and the efficiency of our algorithm, compared with existing methods.Item Modeling and Rendering of Heterogeneous Granular Materials: Granite Application(The Eurographics Association and Blackwell Publishing Ltd, 2007) Soulie, Romain; Merillou, Stephane; Terraz, Olivier; Ghazanfarpour, DjamchidLight-matter interactions is one of the most important factors of realistic rendering. While a lot of work has already been performed in the light transport and simulation area, we believe that virtual materials have not yet been studied enough to achieve a high degree of realism. Some good models exist in order to take into account homogeneous materials. However, there are only a few studies of heterogeneous granular materials. In this paper, we propose a method based on mimicking natural phenomena to take into account these materials. Our study focuses on granite, which can be considered as a heterogeneous agglomerate of individually homogeneous grains. First we present a nucleation/growth process inspired technique giving a full 3D model of granite. Then, we use a rendering process taking into account each material component and subsurface scattering in a simple way.Item Siggraph 2006 Boston, Massachusetts, 30th July-3rd August 2006(The Eurographics Association and Blackwell Publishing Ltd, 2007) Laycock, R.G.; Laycock, S.D.; Ryder, G.; Day, A.M.Item A Survey of General-Purpose Computation on Graphics Hardware(The Eurographics Association and Blackwell Publishing Ltd, 2007) Owens, John D.; Luebke, David; Govindaraju, Naga; Harris, Mark; Krueger, Jens; Lefohn, Aaron E.; Purcell, Timothy J.The rapid increase in the performance of graphics hardware, coupled with recent improvements in its programmability, have made graphics hardware a compelling platform for computationally demanding tasks in a wide variety of application domains. In this report, we describe, summarize, and analyze the latest research in mapping general-purpose computation to graphics hardware.We begin with the technical motivations that underlie general-purpose computation on graphics processors (GPGPU) and describe the hardware and software developments that have led to the recent interest in this field. We then aim the main body of this report at two separate audiences. First, we describe the techniques used in mapping general-purpose computation to graphics hardware. We believe these techniques will be generally useful for researchers who plan to develop the next generation of GPGPU algorithms and techniques. Second, we survey and categorize the latest developments in general-purpose application development on graphics hardware.Item A Survey of Haptic Rendering Techniques(The Eurographics Association and Blackwell Publishing Ltd, 2007) Laycock, S.D.; Day, A.M.Computer Graphics technologies have developed considerably over the past decades. Realistic virtual environments can be produced incorporating complex geometry for graphical objects and utilising hardware acceleration for per pixel effects. To enhance these environments, in terms of the immersive experience perceived by users, the human s sense of touch, or haptic system, can be exploited. To this end haptic feedback devices capable of exerting forces on the user are incorporated. The process of determining a reaction force for a given position of the haptic device is known as haptic rendering. For over a decade users have been able to interact with a virtual environment with a haptic device. This paper focuses on the haptic rendering algorithms which have been developed to compute forces as users manipulate the haptic device in the virtual environment.Item Unpopping: Solving the Image-Space Blend Problem for Smooth Discrete LOD Transitions(The Eurographics Association and Blackwell Publishing Ltd, 2007) Giegl, Markus; Wimmer, MichaelThis paper presents a new, simple and practical algorithm to avoid artifacts when switching between discrete levels of detail (LOD) by smoothly blending LOD representations in image space. We analyse the alternatives of conventional alpha-blending and so-called late-switching (the switching of LODs far enough from the eye-point), widely thought to solve the LOD switching discontinuity problem, and conclude that they either do not work in practice, or defeat the concept of LODs. In contrast we show that our algorithm produces visually pleasing blends for static and animated discrete LODs, for discrete LODs with different types of LOD representations (e.g. billboards and meshes) and even to some extent totally different objects with similar spatial extent, with a very small runtime overhead.