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Now showing 1 - 10 of 23
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    Multimodal Visualization with Interactive Closeups
    (The Eurographics Association, 2009) Ropinski, Timo; Viola, Ivan; Biermann, Martin; Hauser, Helwig; Hinrichs, Klaus; Wen Tang and John Collomosse
    Abstract Closeups are used in illustrations to provide detailed views on regions of interest. They are integrated into the rendering of the whole structure in order to reveal their spatial context. In this paper we present the concept of interactive closeups for medical reporting. Each closeup is associated with a region of interest and may show a single modality or a desired combination of the available modalities using different visualization styles. Thus it becomes possible to visualize multiple modalities simultaneously and to support doctor-to-doctor communication on the basis of interactive multimodal closeup visualizations. We discuss how to compute a layout for 2D and 3D closeups, and how to edit a closeup configuration to prepare a presentation or a subsequent doctor-to-doctor communication. Furthermore, we introduce a GPU-based rendering algorithm, which allows to render multiple closeups at interactive frame rates. We demonstrate the application of the introduced concepts to multimodal PET/CT data sets additionally co-registered with MRI.
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    NURBS-based Inverse Reflector Design
    (The Eurographics Association, 2008) Anson, Oscar; Seron, Francisco J.; Gutierrez, Diego; Luis Matey and Juan Carlos Torres
    Commonly used direct rendering techniques simulate light transport for a complete scene, specified in terms of light sources, geometry, materials, participating media, etc. On the other hand, inverse rendering problems take as input a desired light distribution and try to find the unknown parts of the scene needed to get such light field. The latter kind, where inverse reflector design is included, is traditionally solved by simulation optimization methods, due to the high complexity of the inverse problem. In this paper we present an inverse reflector design method which handles surfaces as NURBS and simulates accurately the light transport by means of a modified photon mapping algorithm. The proposed method is based on an optimization method, called pattern search, in order to compute the reflector needed to generate a target near light field. Some assumptions are determined in order to reduce the complexity of the problem, such as a rotationally symmetric reflector or its perfectly specular reflective behavior. The optimization method specifies the reflector shape by handling a NURBS curve as a generatrix, sequentially modifying the position and weights of its control points in order to obtain the reflector solution. Areas of applications of inverse reflector design span from architectural lighting design to car headlamps design
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    Rendering Discrete Random Media Using Precomputed Scattering Solutions
    (The Eurographics Association, 2007) Moon, Jonathan T.; Walter, Bruce; Marschner, Stephen R.; Jan Kautz and Sumanta Pattanaik
    This paper addresses light transport through a discrete random medium, which we define as a volume filled with macroscopic scattering geometry generated by a random process. This formulation is more general than standard radiative transport, because it can be applied to media that are made up of closely packed scatterers. A new approach to rendering these media is introduced, based on precomputed solutions to a local multiple scattering problem, including a new algorithm for generating paths through random media that moves through the interior of the medium in large strides without considering individual scattering events. A method for rendering homogeneous isotropic random media is described that generates paths using precomputed scattering solutions compressed and randomly sampled using Nonnegative Matrix Factorization. It can efficiently render discrete media, such as a large pile of glass objects, in which the individual scatterers are visible. The method is demonstrated on scenes containing tens of thousands of transparent, specular objects that are nearly impossible to render with standard global illumination techniques.
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    Evolving Sub-Grid Turbulence for Smoke Animation
    (The Eurographics Association, 2008) Schechter, Hagit; Bridson, Robert; Markus Gross and Doug James
    We introduce a simple turbulence model for smoke animation, qualitatively capturing the transport, diffusion, and spectral cascade of turbulent energy unresolved on a typical simulation grid. We track the mean kinetic energy per octave of turbulence in each grid cell, and a novel 'net rotation' variable for modeling the self-advection of turbulent eddies. These additions to a standard fluid solver drive a procedural post-process, layering plausible dynamically evolving turbulent details on top of the large-scale simulated motion. Finally, to make the most of the simulation grid before jumping to procedural sub-grid models, we propose a new multistep predictor to alleviate the nonphysical dissipation of angular momentum in standard graphics fluid solvers.
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    Real Positioning in Virtual Environments Using Game Engines
    (The Eurographics Association, 2007) Chiara, Rosario De; Santo, Valentina Di; Erra, Ugo; Scarano, Vittorio; Raffaele De Amicis and Giuseppe Conti
    Immersive virtual environments offer a natural setting for educational and instructive experiences for users, and game engine technology offers an interesting, cost-effective and efficient solution for building them. In this paper we describe an ongoing project whose goal is to provide a virtual environment where the real location of the user is used to position the user's avatar into the virtual environment.
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    Eulerian Motion Blur
    (The Eurographics Association, 2007) Kim, Doyub; Ko, Hyeong-Seok; D. Ebert and S. Merillou
    This paper describes a motion blur technique which can be applied to rendering fluid simulations that are carried out in the Eulerian framework. Existing motion blur techniques can be applied to rigid bodies, deformable solids, clothes, and several other kinds of objects, and produce satisfactory results. As there is no specific reason to discriminate fluids from the above objects, one may consider applying an existing motion blur technique to render fluids. However, here we show that existing motion blur techniques are intended for simulations carried out in the Lagrangian framework, and are not suited to Eulerian simulations. Then, we propose a new motion blur technique that is suitable for rendering Eulerian simulations.
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    Perception of Clones in Forest Rendering
    (The Eurographics Association, 2010) Purvis, Alan; Sundstedt, Veronica; John Collomosse and Ian Grimstead
    The application of instanced clones represents a powerful technique for reducing the time and space requirements of the storage and visualization of large populations of similar objects. This paper presents the results of several perceptual experiments into the application of cloning to plant populations, within the context of a project to explore the use of resource-acquisition based techniques to model plant distributions. The perceptive effects of clone rotation on human subjects will be explored, with the goal of stratifying clone rotations and minimizing their detection. The perceptual effects of clone number, plant species heterogeneity and appearance will also be explored.
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    Animating Horse Gaits and Transitions
    (The Eurographics Association, 2010) Murphy, James E.; Carr, Hamish; O'Neill, Michael; John Collomosse and Ian Grimstead
    Animations of horses are commonly used for entertainment purposes. A realistic animated model must move with a gait appropriate to its velocity. We present a kinematic animation system in which a horse model moves using gaits and transitions based on predictions from Dynamic Similarity theory. A Genetic Programming technique is used to evolve gait motion with dynamically adjustable limb extent. The system is controlled in real-time using a MIDI controller system based around the model's Froude number. We were successful in producing high quality animations of the horse's natural gaits and transitions.
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    Obscurance-based Volume Rendering Framework
    (The Eurographics Association, 2008) Ruiz, M.; Boada, I.; Viola, I.; Bruckner, S.; Feixas, M.; Sbert, M.; Hans-Christian Hege and David Laidlaw and Renato Pajarola and Oliver Staadt
    Obscurances, from which ambient occlusion is a particular case, is a technology that produces natural-looking lighting effects in a faster way than global illumination. Its application in volume visualization is of special interest since it permits us to generate a high quality rendering at a low cost. In this paper, we propose an obscurancebased framework that allows us to obtain realistic and illustrative volume visualizations in an interactive manner. Obscurances can include color bleeding effects without additional cost. Moreover, we obtain a saliency map from the gradient of obscurances and we show its application to enhance volume visualization and to select the most salient views.
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    Synthesis of Interactive Hand Manipulation
    (The Eurographics Association, 2008) Liu, C. Karen; Markus Gross and Doug James
    We present an interactive physics-based motion synthesis technique for creating hand manipulation across a wide variety of tasks, objects, user interventions, and stylistic preferences. Given an object being manipulated, a single pose specifying the desired initial contact, and the kinematic goals of the manipulation, our algorithm automat- ically generates hand-object manipulation that is responsive to unscripted external disturbances. Our algorithm simulates the dynamic coupling between a passive dynamic system and an active dynamic system by formulating a sequence of constrained optimizations. This formulation allows the user to synthesize a manipulation task by describing simple, keyframe-like kinematic goals in the domain of object configuration. The algorithm will auto- matically produce the hand motion that achieves the kinematic goals via coupled dynamic equations of motion.