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Item Surfel Octrees: A New Scheme for Interactive Inspection of Anatomy Atlases in Client-Server Applications(The Eurographics Association, 2015) Surinyac, Jordi; Brunet, Pere; Mateu Sbert and Jorge Lopez-MorenoNowadays, an increasing interest on tele-medicine and tele-diagnostic solutions can be observed, with client/server architectures for remote inspection of volume image-based medical data which are becoming more and more popular. The use of portable devices is gradually spreading due to their portability and easy maintenance. In this paper, we present an efficient data model for segmented volume models based on a hierarchical data structure of surfels per anatomical structure. Surfel Octrees are compact enough for transmission through networks with limited bandwidth, and provide good visual quality in the client devices at a limited footprint. Anatomy atlases are represented as octree forests, supporting local interaction in the client device and selection of groups of medical organs. After presenting the octree generation and interaction algorithms, we present several examples and discuss the interest of the proposed approach in low-end devices such as mobiles and tablets.Item GPU Visualization and Voxelization of Yarn-Level Cloth(The Eurographics Association, 2014) Lopez-Moreno, Jorge; Cirio, Gabriel; Miraut, David; Otaduy, Miguel Angel; Adolfo Munoz and Pere-Pau VazquezMost popular methods in cloth rendering rely on volumetric data in order to model complex optical phenomena such as sub-surface scattering. Previous work represents yarns as a sequence of identical but rotated crosssections. While these approaches are able to produce very realistic illumination models, the required volumetric representation is difficult to compute and render, forfeiting any interactive feedback. In this paper, we introduce a method based on the GPU for simultaneous visualization and voxelization, suitable for both interactive and offline rendering. Our method can interactively voxelize millions of polygons into a 3D texture, generating a volume with sub-voxel accuracy which is suitable even for high-density weaving such as linen.Item From the Patient to the Surgery - A Complete Computer Vision and Graphics Process(The Eurographics Association, 2012) Martinez, A.; Jimenez, J.; Isabel Navazo and Gustavo PatowGenerating digital information ready to use on a surgery operation from a patient is a complex process. This process involves computer vision techniques, in order to extract digital information from medical images, and computer graphics techniques in order to generate proper models to interact with the digital information. In this approach a set of techniques covering both fields (computer vision and graphics) have been used to develop a complete process from the medical image to the surgery training.Item A New Approach for Perceptually-based Fitting Strokes into Straight Segments(The Eurographics Association, 2015) Plumed, Raquel; Company, Pedro; Varley, Peter A. C.; Mateu Sbert and Jorge Lopez-MorenoFitting the strokes of a sketch into geometrical primitives is still an open problem, even for sketches which depict bare line-drawings without annotations. Such sketches comprise only discrete strokes, sequences of points obtained between a pen down and a pen up. It is commonly accepted that the best perceptual fittings depend on the context. Hence, we will only be able to extract the best line-drawing from a sketch by considering a complex recognition flow, where lines must be iteratively fitted according to different tentative relationships until the most plausible line-drawing is reached. The recognition task considered in this paper is determining whether a stroke represents a straight line. The goal is doing it in a way that allows for iterative recognition flows. The novel contributions are that our approach is more fast and robust than accurate, uses perceptual criteria to classify strokes, and returns likeliness instead of a simple yes/no.Item Image-Based Flow Transfer(The Eurographics Association, 2014) Bosch, Carles; Patow, Gustavo A.; Adolfo Munoz and Pere-Pau VazquezWeathering phenomena are ubiquitous to urban environments. In particular, fluid flow becomes a specially representative but difficult phenomenon to reproduce. In order to produce realistic flow effects, it is possible to take advantage of the widespread availability of flow images on the internet, which can be used to gather key information about the flow. In this paper we present a technique that allows transferring flow phenomena between photographs, adapting the flow to the target image and giving the user flexibility and control through specifically tailored parameters. This is done through two types of control curves: a fitted theoretical curve for the mass of deposited material, and a control curve extracted from the images for the color. This way, the user has a set of simple and intuitive parameters and tools to control the flow phenomena on the target image. To illustrate our technique, we present a complete set of images that somewhat cover a large range of flow phenomena in urban environments.Item Uncertainty Visualization of Brain Fibers(The Eurographics Association, 2012) Hermosilla, Pedro; Brecheisen, Ralph; Vázquez, Pere-Pau; Vilanova, Anna; Isabel Navazo and Gustavo PatowDiffuse Tensor Imaging (DTI) is an acquisition method based on Magnetic Resonance (MR) that provides information on the white matter fiber pathways in the living human brain. Such knowledge is crucial for understanding the way different parts of the brain work and how they interact with each other. The reconstruction of fiber tracts, however, depends on a number of parameters that introduce a degree of uncertainty in the data. Together with the parameter setting, other elements such as noise, motion, partial volume effects, or image artifacts increase the uncertainty. Therefore, fiber tracking algorithms may produce misleading results. Visualizing such uncertainty is important to avoid taking wrong decisions in medical environments. In this paper we present a set of techniques that provide a better understanding on the visualization of brain fibers by means of textures, silhouettes, ambient occlusion, and animation.Item PREFR: A Flexible Particle Rendering Framework(The Eurographics Association, 2015) Galindo, Sergio E.; Toharia, Pablo; Lopez-Moreno, Jorge; Robles, Oscar D.; Pastor, Luis; Mateu Sbert and Jorge Lopez-MorenoWe present PREFR (Particle REndering FRamework): a first approach to a general-purpose particle rendering framework on the standard OpenGL architecture, designed with the goal of being easily configured by the user without compromising efficiency. In this paper, we analyze and discuss the performance of each stage involved in particle rendering in order to improve its efficiency for future versions with additional GPGPU computation steps or multicore parallelization techniques. Finally, we show the potential of our particle engine by tackling two very different problems: The rendering of neuronal electrical impulses in physiological models of the human brain, and the visualization of emergent patterns for information analysis, specifically emphasizing structured information in a complex data set.Item Locating Companies in 3D Urban Environments on the Internet(The Eurographics Association, 2012) Estrella, Ana M. López; Ortega, M. Dolores Robles; Alvarado, Lidia Ortega; Higueruela, Francisco R. Feito; Isabel Navazo and Gustavo Patow3D visualization is being incorporated in a lot of fields, including Geographic Information Systems (GIS). In addition, the Internet is the most popular method to find information, due to its accessibility. For this reason, most companies and businesses are interested in showing their products on the Web to make them well-known to many people. Considering all these concepts, this paper explains the process of developing a web application prototype with some GIS features. The main goal is to obtain business information, the location and the 2.5D navigation in an urban environment. In this way, through a web browser, the user will be able to search for companies by category, get information and see the scene from different levels of detail.Item Management of 3D Geometry on Portable Devices(The Eurographics Association, 2012) Martínez, José Olmos; Romero, Francisco Ramos; Gonzalez, Carlos; Isabel Navazo and Gustavo PatowThe mobile devices has evolutioned quickly in the recent years. The Games industry realized the great potential of these devices and made many developments whose requirements makes devices reach their hardware limits so there is a need to improve performance. One way is to study different forms for efficient 3D models visualizations.Item A System Proposal for Interactive Deformation of Large Medical Volumes(The Eurographics Association, 2014) Aguilera, Alejandro Rodríguez; Leon, Alejandro; Escudero, Luis López; Sánchez, Manuel García; Adolfo Munoz and Pere-Pau VazquezIn the field of volume deformation, an open research topic is the interactive and physically plausible deformation and rendering of large medical volumes. Many approaches to deform volumetric models have been proposed, offering a trade-off between realism and model resolution depending on the goal. In this paper, we study the main techniques to deform volumetric models, focusing on the works that address interactive realistic deformation of large models and we outline the requirements needed to build an integrated system to interactively deform and visualize large volumes using the GPU. We also present a prototype of application that shows the viability of implementing such a system. For this prototype, we propose an enhanced deformation technique and a new fast deformed volume visualization scheme, assuring the system interactivity at any time.