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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 Polynomial Approximation of Blinn-Phong Model(The Eurographics Association, 2006) Öztürk, Aydin; Bilgili, Ahmet; Kurt, Murat; Louise M. Lever and Mary McDerbyThe Phong model has been one of the oldest and the most popular reflection models in Computer Graphics. It can be used to model specular highlights of various materials. In this paper, we consider a polynomial model and obtain a linear approximation of the Blinn-Phong model. Approximation errors were obtained for the proposed model and empirical comparisons were made using a measured BRDF data set. Based on the empirical results, it is shown that proposed model provides visually convincing representation of BRDF and performs well for modeling the surface reflectance.Item Perception-based Lighting Design(The Eurographics Association, 2006) Ha, Hai Nam; Olivier, Patrick; Louise M. Lever and Mary McDerbyPerception-based lighting design approaches model image quality using a cognitively grounded objective function which is in turn optimised through manipulation of the lighting parameters of a scene. We present, and demonstrate, a detailed implementation of perception-based lighting design, including the application and evaluation of stochastic optimisation using genetic algorithms.Item Perceived Rendering Thresholds for High-Fidelity Graphics on Small Screen Devices(The Eurographics Association, 2006) Aranha, M.; Debattista, K.; Chalmers, A.; Hill, S.; Louise M. Lever and Mary McDerbySmall screen devices, also known as small-form-factor (SFF) devices including mobile phones and ultra mobile PCs are increasingly ubiquitous. Their uses includes gaming, navigation and interactive visualisation. SFF devices are, however, inherently limited by their physical characteristics for perception as well as limited processing and battery power. High-fidelity graphic systems have significant computational requirements which can be reduced through use of perceptually-based rendering techniques. In order to exploit these techniques on SFF devices a sound understanding of the perceptual characteristics of the display device is needed. This paper investigates the perceived rendering threshold specific for SFF devices in comparison to traditional display devices. We show that the threshold for SFF systems differs significantly from typical displays indicating substantial savings in rendering quality and thus computational resources can be achieved for SFF devices.Item 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 Physically Based Simulation and Visualization of Fire in Real-Time using the GPU(The Eurographics Association, 2006) Rødal, Samuel; Storli, Geir; Gundersen, Odd Erik; Louise M. Lever and Mary McDerbyIn this paper we present a physically based framework for real-time simulation and visualization of fire using the GPU. The physics of fire is modeled through a combination of a fluid solver and a combustion process causing the characteristic motion of fire. The simulation results are then rendered using a particle system combined with a black-body radiation model where the physically based simulation governs both the motion and appearance of the particles. By performing individual slice simulations in 2D and combining them using volumetric extrusion we achieve better performance than by performing the simulation in 3D without compromising the visual quality. Thus, achieving our goal of visualizing bonfire and torch-like fire effects with high visual quality in real-time.Item Fast Rendering of Complex Dynamic Scenes(The Eurographics Association, 2006) KovalcÃk, Vit; Sochor, Jiri; Louise M. Lever and Mary McDerbyWe present a novel algorithm capable of rendering complex dynamic scenes at high frame rates. The key part of the algorithm is occlusion culling which is performed by an optimized usage of the hardware occlusion queries. The spatial organization of the scene using 2-level BSP-like hierarchy helps to speed up evaluating full and partial occlusion of the objects. The algorithm handles both static and dynamic objects and places no restrictions on the shape of objects.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.Item Structured Image Techniques for Efficient High-Fidelity Graphics(The Eurographics Association, 2006) Yang, X.; Debattista, K.; Chalmers, A.; Louise M. Lever and Mary McDerbyGlobal illumination rendering in real-time for high-fidelity graphics remains one of the biggest challenges for computer graphics in the foreseeable future. Recent work has shown that significant amounts of time can be saved by selectively rendering in high quality only those parts of the image that are considered perceptually more important. Regions of the final rendering that are deemed more perceptually important can be identified through lower quality, but rapid, rasterisation rendering. By exploiting this prior knowledge of the scene and taking advantage of image space based algorithms to concentrate rendering on the more salient areas higher performance rendering may be achieved. In this paper, we present a selective rendering framework based on ray tracing for global illumination which uses a rapid image preview of the scene to identify important image regions, structures these regions and uses this knowledge to direct a fraction of the rays traditionally shot. The undersampled image is then reconstructed using algorithms from image processing. We demonstrate that while this approach is able to significantly reduce the amount of computation it still maintains a high perceptual image quality.