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Item Multimodal Visualization with Interactive Closeups(The Eurographics Association, 2009) Ropinski, Timo; Viola, Ivan; Biermann, Martin; Hauser, Helwig; Hinrichs, Klaus; Wen Tang and John CollomosseAbstract 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.Item NURBS-based Inverse Reflector Design(The Eurographics Association, 2008) Anson, Oscar; Seron, Francisco J.; Gutierrez, Diego; Luis Matey and Juan Carlos TorresCommonly 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 designItem Perception of Clones in Forest Rendering(The Eurographics Association, 2010) Purvis, Alan; Sundstedt, Veronica; John Collomosse and Ian GrimsteadThe 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.Item Animating Horse Gaits and Transitions(The Eurographics Association, 2010) Murphy, James E.; Carr, Hamish; O'Neill, Michael; John Collomosse and Ian GrimsteadAnimations 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.Item Estimación de Densidades usando GPUs(The Eurographics Association, 2008) Lastra, M.; Urena, C.; Bittner, J.; García, R.; Montes, R.; Luis Matey and Juan Carlos TorresEste artículo presenta un método de estimación de densidades basado en rayos que ha sido implementado completamente en la GPU. La estimación de densidades basada en rayos reduce el sesgo de los enfoques clásicos basados en fotones aunque tiene un costo computacional más alto. Proponemos algoritmos y estructuras de datos para la implementación en GPUs de la estimación de densidades basada en rayos y mostramos que la técnica propuesta da hasta un orden de magnitud de aceleración comparada con su variante CPU. La aceleración obtenida se incrementa al aumentar el número de rayos y por tanto el método es muy útil en aplicaciones que requieran renderización de alta calidad.Item Grammatical Evolution for Gait Retargeting(The Eurographics Association, 2008) Murphy, James E.; Carr, Hamish; O'Neill, Michael; Ik Soo Lim and Wen TangArtists and scientists require tools to construct physics-based animal models. However, animating these models requires motion data for realistic movement. Motion data may either be measured from real-life animals-in-motion or generated using an optimisation approach. We propose a solution for retargeting gait data from one animal to another. The retargeted gait cycles are generated using a Grammatical Evolution optimisation approach and the search space is constrained based on dynamic similarity principles.