CEIG12
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Item WebGL-based Visualization of Voxelized Brain Models(The Eurographics Association, 2012) Torre, J. Cruz de la; Ibáñez, J. Jiménez; Estrella, A. M. López; Miras, J. Ruiz de; Isabel Navazo and Gustavo PatowThis work presents our preliminary results on the interactive construction and visualization of voxelized brain models into Web platforms by using WebGL. Our voxel model is a non-usual level of detail (LOD) representation based on the box-counting algorithm used to calculate the fractal dimension of 3D brain images. Our results to date show a promising solution based on a client-server approach.Item Analysis of Coded Apertures for Defocus Deblurring of HDR Images(The Eurographics Association, 2012) Garcia, Luis; Presa, Lara; Gutierrez, Diego; Masia, Belen; Isabel Navazo and Gustavo PatowIn recent years, research on computational photography has reached important advances in the field of coded apertures for defocus deblurring. These advances are known to perform well for low dynamic range images (LDR), but nothing is written about the extension of these techniques to high dynamic range imaging (HDR). In this paper, we focus on the analysis of how existing coded apertures techniques perform in defocus deblurring of HDR images. We present and analyse three different methods for recovering focused HDR radiances from an input of blurred LDR exposures and from a single blurred HDR radiance, and compare them in terms of the quality of their results, given by the perceptual metric HDR-VDP2. Our research includes the analysis of the employment of different statistical deconvolution priors, made both from HDR and LDR images, performing synthetic experiments as well as real ones.Item Ventricular Puncture Trainer(The Eurographics Association, 2012) Pandiella, Imanol Muñoz; Monclús, Eva; Brunet, Pere; Conesa, Gerard; Isabel Navazo and Gustavo PatowThe learning process in neurosurgery is a large and difficult task based on experimentation, being ventriculostomy not an exception. We have developed a virtual reality system to help training novel surgeons on this kind of operation. The system consists of the simulation of the surgery using a haptic device and a subsequent 3D visual inspection of the surgical trajectory. Our main objective was to proof that the tactile sensation produced by our system was enough realistic for the surgeons. We carried out a demonstration session in a medical workshop where all surgeons attending the workshop used the system with a very enthusiastic response about the perception experimented through the system.Item Design of a Game Creation Environment(The Eurographics Association, 2012) Chover, M.; Folch, F.; González, C.; Gumbau, J.; Quirós, R.; Rebollo, C.; Remolar, I.; Sánchez, I.; Isabel Navazo and Gustavo PatowThere are many tools nowadays for videogame development. Generally, this kind of tools have been created for users with programming skills. This restriction, although is useful to programmers, excludes other professionals like graphics artists or designers. For this reason we propose an intuitive and simple environment that let professionals to design videogames without any programming knowledge. Our design allows to develop complex games visually without writing a single line of code, allowing to create game objects (actors) with complex interaction. The work uses a visual approach with diagrams for the specification of rules which are be defined without need of programming.Item PrimeSense Sensors as a Low-cost Method for Motion Capture on Clinical Tests(The Eurographics Association, 2012) Sanmartín, G.; Flores, J.; Arias, P.; Cudeiro, J.; Méndez, R.; Isabel Navazo and Gustavo PatowVirtual Reality (VR) is the computer recreation of simulated environments that create on the user a sense of physical presence. VR provides the advantages of being highly flexible and controllable, allowing experts to generate the optimal conditions for any given test and isolating any desired variables in the course of an experiment. An important feature of VR is that it allows interaction within the virtual world. Motion capture is one of the most popular technologies, because it contributes to creating in the subject the sense of presence. There are several methods to incorporate these techniques into an VR system, with the challenge of them not being too invasive. We propose a method using PrimeSense sensors and several computer vision techniques to build a low-cost system that has proven to be valid in its application as a support therapy for Parkinson's disease (PD) patients.Item A GPU Based Method for the Automatic Generation of Near-Optimal Navigation Meshes(The Eurographics Association, 2012) Oliva, Ramon; Pelechano, Nuria; Isabel Navazo and Gustavo PatowIn this paper we present a novel, robust and efficient GPU based technique to automatically generate a Navigation Mesh for complex 3D scenes. Our method consists of two steps: firstly, starting with a 3D scene representing a complex environment of one floor with slopes, steps, and other obstacles, it automatically generates a 2D representation based on a single polygon (floor) with holes (obstacles).This step can handle degeneracies of the starting 3D scene model, such as interpenetrating geometry. Secondly, a novel method that exploits the GPU efficiency is used to automatically generate a near-optimal convex decomposition which will represent the cell and portal graph of the environment. Such convex decomposition is a 2D representation of the walkable areas of the environment with portals indicating the crossing borders. The results show that the presented technique not only is more robust than previous CPU methods, but also for the tested environments with up to 1000 vertices, it performs five times faster.Item Multi-resolution Myocardial Architecture Study(The Eurographics Association, 2012) Poveda, F.; Gil, D.; Gurgui, T.; Marti, E.; Isabel Navazo and Gustavo PatowMyocardial complexity has lead to vivid controversy in the interpretation of the cardiac form and function over the years. This complexity has not been clarified yet even with the most recent computational reconstructions of low level MRI data.We propose a data-based multi-resolution methodology and validation to tackle this problem.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 Computing Curvature Information on 3D Meshes from Cultural Heritage Artifacts(The Eurographics Association, 2012) López, L.; Torres, J. C.; Soler, F.; Isabel Navazo and Gustavo PatowThe curvature provides essential information about the features of a object surface. This poster presents an operation that makes it possible to generate the curvature information in the CHiSEL system.Item Differential Ray Marching(The Eurographics Association, 2012) Muñoz, Adolfo; Isabel Navazo and Gustavo PatowSeveral participating media rendering algorithms are based on ray marching: they integrate the variations of radiance along the volume covered by the participating media by splitting the path of light into segments and sampling light contribution at each of those segments. This paper revisits the concept of ray marching not as an integration technique, but as the application of a numerical method to solve an initial value differential equation. We present how to apply different numerical methods as ray marching techniques, analyze a wide range of them and study their applicability under different scenarios. Furthermore, we show how each of them improves over traditional ray marching. Any participating media rendering algorithm that is based on ray marching will benefit from the application of our technique by reducing the number of needed samples (and therefore, rendering time) and/or increasing accuracy.Item Generating Coherent Ray Directions in Path Tracing(The Eurographics Association, 2012) Torres, Roberto; Martín, Pedro J.; Gavilanes, Antonio; Isabel Navazo and Gustavo PatowThe quality of the images produced by a global illumination rendering engine is highly connected to the number of paths that are randomly generated from the camera to the light sources. Graphics Processing Units (GPUs) have been used to implement renderers by typically binding each thread to a ray. Nevertheless, this purely random generation does not fit well on the architecture of current GPUs, due to their SIMD nature. We modify the way paths are extended in order to take the most of GPUs. The arrangement of rays is split into groups of contiguous rays. The hemisphere on each intersection point is divided into spherical patches, and the same patch is chosen for all the rays in the group. The next direction for each path will be randomly chosen on that patch. Thus, if the intersection points of a group are near, the new rays spawned will be similar. We have implemented different configurations of this idea on a path tracer in CUDA and they have been experimentally tested on usual scenes. In the same amount of time, most of our algorithms complete more paths and, therefore, they produce images of higher quality than those obtained by the purely random generation.Item High Resolution Medical 3D Data Sets on Mobile Devices and WebGL(The Eurographics Association, 2012) Jimenez, Juan-Roberto; Noguera, Jose Maria; Isabel Navazo and Gustavo PatowNowadays, mobile devices and the web are being used to deliver 3D graphics to mass users. However, applications such as visualization of high resolution medical models are still impossible to handle in such platforms due to texture limitations, mainly the lack of 3D texture support. In this paper we propose a software architecture and a novel texture storage technique that overcome these limitations. In addition, our proposal allows us to adapt existing direct volume rendering techniques based on 3D textures to mobile devices and WebGL. Our experiments demonstrate the feasibility and validity of our proposal to render high resolution volumetric models on both platforms.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 An Application to Interact with 3D Models Reconstructed from Medical Images(The Eurographics Association, 2012) Paulano, F.; Pulido, R.; Jiménez, J. J.; Isabel Navazo and Gustavo PatowAlthough the reconstruction of 3D models from medical images is not an easy task, there are many algorithms to perform it. However, the reconstructed models are usually large, have a lot of outliers and have not a correct topology. For that reason, the algorithms used to interact with them must be fast and robust. In this paper, we present an application that enables the interaction with models reconstructed from medical images. The application uses Marching Cubes to generate triangle soups from the medical images. Then, the user can define models by selecting a set of triangles. Once the models have been defined, the application allows to interact with them. In addition, a detailed collision detection is calculated between the models in the scene in order not only to avoid that models in the scene collide, but also to determine which triangles are overlapping. In addition, the calculation of distances and nearest points provides visual aid when the user is interacting with the models.Item A Procedural Modeling System for the Creation of Huge Models(The Eurographics Association, 2012) Cubero, Francisco; Mas, Albert; Patow, Gustavo; Isabel Navazo and Gustavo PatowThis paper presents a new general purpose procedural geometrical modeling system. It is focused on providing flexibility, modularity and scalability. Furthermore, it is taylored to manage huge geometric models, with millions of polygons. An out-of-core memory management system assures that any scene size can be generated during the modeling evolution. This generation is performed by a set of rules and operations on geometrical objects, organized as a directed acyclic graph.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 Evaluating Three Versions of an Augmented Reality Mobile Game about Recycling(The Eurographics Association, 2012) Furió, D.; Juan, M.-Carmen; Alem, L.; Ashworth, P.; Isabel Navazo and Gustavo PatowWe present three versions of an Augmented Reality (AR) game (basic, collaborative and competitive) for changing people attitudes with regard to climate change. We present a study in which twenty-eight primary school students have participated. To explore the extent to which the three AR game versions affected different aspects, the children had to answer questionnaires. The results did not show significant differences between the three versions. However, having into account the means and children preference, the competitive version could have had more influence on the participants.Item Lineal Hull: Two Algorithms for Convex Hull(The Eurographics Association, 2012) Sánchez, M. García; Salas, A. León; Cantero, J. C. Torres; Isabel Navazo and Gustavo PatowThis poster proposes a concept that improves the existing algorithms for convex hull. This concept can be applied whether the initial points are sorted or not. The results show a comparation with Quick-Hull (QH) [BDH96]Item Interactive Generation of (Paleontological) Scientific Illustrations from 3D-models(The Eurographics Association, 2012) Schäfer, Sebastian; Knopp, Christoph; Krömker, Detlef; Isabel Navazo and Gustavo PatowScientific illustrations play an important role in the paleontological domain and are complex illustrations that are manually drawn. The artist creates illustrations that feature common expressive painting techniques: outlines, both irregular and periodic stippling as well as an abstract shaded surface in the background. We present a semiautomatic tool to generate these illustrations from 3D-models in real-time. It is based on an extensible GPU-based pipeline to interactively render characteristic into image-layers that are combined in an image-editing fashion. The user can choose the techniques used to render each layer and manipulate its key aspects. Using 3D- and 2D-painting the artist can still interact with the result and adjust it to his or her liking.