CEIG14

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https://diglib.eg.org/handle/10.2312/7709

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    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 Vazquez
    In 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.
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    CLIKSA - An Application for Physics Education in Secondary School
    (The Eurographics Association, 2014) Marín-Lora, Carlos; García-Fernández, Ignacio; Adolfo Munoz and Pere-Pau Vazquez
    In this paper we present an application for teaching Physics courses in secondary education. It is a web application, based on HTML5 and on JavaScript. We rely on the graphical capabilities of this technology, including rendering on 2D canvas context and SVG rendering, and we develop a framework for simulating physics behavior. We review other applications with similar features, explaining the motivations of the current development. The system architecture and the software design are discussed and the simulation techniques are explained. We finish with a discussion on some possible examples of use for the application and on the future development plans.
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    CEIG 2014 Frontmatter
    (Eurographics Assiciation, 2014) Muñoz, Adolfo; Vázquez, Pere-Pau
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    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 Vazquez
    Most 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.
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    Low Cost Recovery of Spectral Power Distributions
    (The Eurographics Association, 2014) Alvarez, Sara; Presa, Lara; Kunkel, Timo; Masia, Belen; Adolfo Munoz and Pere-Pau Vazquez
    Measuring the spectral power distribution of a light source, that is, the emission as a function of wavelength, typically requires the use of spectrophotometers or multispectral cameras. Here, we propose a low-cost system that enables the recovery of the visible light spectral signature of different types of light sources without requiring highly complex or specialized equipment and using just off-the-shelf, widely available components. To do this, a standard DSLR camera and a diffraction filter are used, sacrificing the spatial dimension for spectral resolution. We present here the image formation model and the calibration process necessary to recover the spectrum, including spectral calibration and amplitude recovery. We also show applications of the system in image processing and rendering.
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    CAVAST: The Crows Animation, Visualization, and Simulation Testbed
    (The Eurographics Association, 2014) Beacco, Alejandro; Pelechano, Nuria; Adolfo Munoz and Pere-Pau Vazquez
    Simulation, animation and rendering of crowds has become an important part of real-time applications such as videogames. Virtual environments achieve higher realism when being populated by virtual crowds as opposed to appearing uninhabited. There has been a large amount of research on simulation, animation and rendering of crowds, but in most cases they seem to be treated separately as if the limitations in one area did not affect the others. At the end of the day the goal is to populate environments with as many characters as possible in real time, and it is of little use if one can for instance render thousands of characters in real time, but you cannot move more than a hundred due to a simulation bottleneck. The goal of our work is to provide a framework that lets the researcher focus on each of these topics at a time (simulation, animation, or rendering) and be able to explore and push the boundaries on one topic without being strongly limited by the other related issues. This paper presents therefore a new prototyping testbed for crowds that lets the researcher focus on one of these areas of research at a time without loosing sight of the others. We offer default representations, animation and simulation controllers for real time crowd simulation, that can easily be replaced or extended. Fully configurable level-of-detail for both rendering and simulation is also available.
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    Image-Based Flow Transfer
    (The Eurographics Association, 2014) Bosch, Carles; Patow, Gustavo A.; Adolfo Munoz and Pere-Pau Vazquez
    Weathering 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.
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    Depth from a Single Image Through User Interaction
    (The Eurographics Association, 2014) Lopez, Angeles; Garces, Elena; Gutierrez, Diego; Adolfo Munoz and Pere-Pau Vazquez
    In this paper we present a method to obtain a depth map from a single image of a scene by exploiting both image content and user interaction. Assuming that regions with low gradients will have similar depth values, we formulate the problem as an optimization process across a graph, where pixels are considered as nodes and edges between neighbouring pixels are assigned weights based on the image gradient. Starting from a number of userdefined constraints, depth values are propagated between highly connected nodes i.e. with small gradients. Such constraints include, for example, depth equalities and inequalities between pairs of pixels, and may include some information about perspective. This framework provides a depth map of the scene, which is useful for a number of applications.
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    Improving Depth Estimation Using Superpixels
    (The Eurographics Association, 2014) Cambra, Ana B.; Muñoz, Adolfo; Murillo, Ana C.; Guerrero, José J.; Gutierrez, Diego; Adolfo Munoz and Pere-Pau Vazquez
    This work is focused on assigning a depth label to each pixel in the image. We consider off-the-shelf algorithms that provide depth information from multiple views or depth information directly obtained from RGB-d sensors. Both of them are common scenarios of a well studied problem where many times we get incomplete depth information. Then, user interaction becomes necessary to finish, improve or correct the solution for certain applications where accurate and dense depth information for all pixels in the image is needed. This work presents our approach to improve the depth assigned to each pixel in an automated manner. Our proposed pipeline combines state-of-the art methods for image superpixel segmentation and energy minimization. Superpixel segmentation reduces complexity and provides more robustness to the labeling decisions. We study how to propagate the depth information to incomplete or inconsistent regions of the image using a Markov Random Field (MRF) energy minimization framework. We propose and evaluate an energy function and validate it together with the designed pipeline. We present a quantitative evaluation of our approach with different variations to show the improvements we can obtain. This is done using a publicly available stereo dataset that provides ground truth information. We show additional qualitatively results, with other tests cases and scenarios using different input depth information, where we also obtain significant improvements on the depth estimation compared to the initial one.