Brunet Crosa, Pere
Total activity: 215
Department
Department of Software
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perelsi.upc.edu
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1 to 50 of 215 results
  • Cage-free spatial deformations

     Cervero Abello, Maria Angels; Vinacua Pla, Alvaro; Brunet Crosa, Pere
    International Conference on Computer Graphics Theory and Applications and International Conference on Information Visualization Theory and Applications
    Presentation's date: 2013-02
    Presentation of work at congresses

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    We propose a new deformation scheme for polygonal meshes through generalized barycentric coordinates that does not require any explicit cage definition. Our system infers the connectivity of the control points defined by the user and computes the coordinates using this structure. This allows the user to incrementally position the control points (or delete them) wherever he considers more suitable. This freedom gives more control, precision and locality to the deformation process.

  • Enhanced Perception in Volume Visualization  Open access

     Díaz Iriberri, José
    Defense's date: 2013-04-26
    Universitat Politècnica de Catalunya
    Theses

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    Due to the nature of scientic data sets, the generation of convenient visualizations may be a difficult task, but crucial to correctly convey the relevant information of the data. When working with complex volume models, such as the anatomical ones, it is important to provide accurate representations, since a misinterpretation can lead to serious mistakes while diagnosing a disease or planning surgery. In these cases, enhancing the perception of the features of interest usually helps to properly understand the data. Throughout years, researchers have focused on different methods to improve the visualization of volume data sets. For instance, the definition of good transfer functions is a key issue in Volume Visualization, since transfer functions determine how materials are classified. Other approaches are based on simulating realistic illumination models to enhance the spatial perception, or using illustrative effects to provide the level of abstraction needed to correctly interpret the data. This thesis contributes with new approaches to enhance the visual and spatial perception in Volume Visualization. Thanks to the new computing capabilities of modern graphics hardware, the proposed algorithms are capable of modifying the illumination model and simulating illustrative motifs in real time. In order to enhance local details, which are useful to better perceive the shape and the surfaces of the volume, our first contribution is an algorithm that employs a common sharpening operator to modify the lighting applied. As a result, the overall contrast of the visualization is enhanced by brightening the salient features and darkening the deeper regions of the volume model. The enhancement of depth perception in Direct Volume Rendering is also covered in the thesis. To do this, we propose two algorithms to simulate ambient occlusion: a screen-space technique based on using depth information to estimate the amount of light occluded, and a view-independent method that uses the density values of the data set to estimate the occlusion. Additionally, depth perception is also enhanced by adding halos around the structures of interest. Maximum Intensity Projection images provide a good understanding of the high intensity features of the data, but lack any contextual information. In order to enhance the depth perception in such a case, we present a novel technique based on changing how intensity is accumulated. Furthermore, the perception of the spatial arrangement of the displayed structures is also enhanced by adding certain colour cues. The last contribution is a new manipulation tool designed for adding contextual information when cutting the volume. Based on traditional illustrative effects, this method allows the user to directly extrude structures from the cross-section of the cut. As a result, the clipped structures are displayed at different heights, preserving the information needed to correctly perceive them.

    Debido a la naturaleza de los datos científicos, visualizarlos correctamente puede ser una tarea complicada, pero crucial para interpretarlos de forma adecuada. Cuando se trabaja con modelos de volumen complejos, como es el caso de los modelos anatómicos, es importante generar imágenes precisas, ya que una mala interpretación de las mismas puede producir errores graves en el diagnóstico de enfermedades o en la planificación de operaciones quirúrgicas. En estos casos, mejorar la percepción de las zonas de interés, facilita la comprensión de la información inherente a los datos. Durante décadas, los investigadores se han centrado en el desarrollo de técnicas para mejorar la visualización de datos volumétricos. Por ejemplo, los métodos que permiten definir buenas funciones de transferencia son clave, ya que éstas determinan cómo se clasifican los materiales. Otros ejemplos son las técnicas que simulan modelos de iluminación realista, que permiten percibir mejor la distribución espacial de los elementos del volumen, o bien los que imitan efectos ilustrativos, que proporcionan el nivel de abstracción necesario para interpretar correctamente los datos. El trabajo presentado en esta tesis se centra en mejorar la percepción de los elementos del volumen, ya sea modificando el modelo de iluminación aplicado en la visualización, o simulando efectos ilustrativos. Aprovechando la capacidad de cálculo de los nuevos procesadores gráficos, se describen un conjunto de algoritmos que permiten obtener los resultados en tiempo real. Para mejorar la percepción de detalles locales, proponemos modificar el modelo de iluminación utilizando una conocida herramienta de procesado de imágenes (unsharp masking). Iluminando aquellos detalles que sobresalen de las superficies y oscureciendo las zonas profundas, se mejora el contraste local de la imagen, con lo que se consigue realzar los detalles de superficie. También se presentan diferentes técnicas para mejorar la percepción de la profundidad en Direct Volume Rendering. Concretamente, se propone modificar la iluminación teniendo en cuenta la oclusión ambiente de dos maneras diferentes: la primera utiliza los valores de profundidad en espacio imagen para calcular el factor de oclusión del entorno de cada pixel, mientras que la segunda utiliza los valores de densidad del volumen para aproximar dicha oclusión en cada vóxel. Además de estas dos técnicas, también se propone mejorar la percepción espacial y de la profundidad de ciertas estructuras mediante la generación de halos. La técnica conocida como Maximum Intensity Projection (MIP) permite visualizar los elementos de mayor intensidad del volumen, pero no aporta ningún tipo de información contextual. Para mejorar la percepción de la profundidad, proponemos una nueva técnica basada en cambiar la forma en la que se acumula la intensidad en MIP. También se describe un esquema de color para mejorar la percepción espacial de los elementos visualizados. La última contribución de la tesis es una herramienta de manipulación directa de los datos, que permite preservar la información contextual cuando se realizan cortes en el modelo de volumen. Basada en técnicas ilustrativas tradicionales, esta técnica permite al usuario estirar las estructuras visibles en las secciones de los cortes. Como resultado, las estructuras de interés se visualizan a diferentes alturas sobre la sección, lo que permite al observador percibirlas correctamente.

  • Ventricular puncture trainer

     Monclús Lahoya, Eva; Muñoz Pandiella, Imanol; Brunet Crosa, Pere; Conesa, Gerard
    Congreso Español de Informática Gráfica
    Presentation's date: 2012
    Presentation of work at congresses

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  • Example-guided segmentation

     Chica Calaf, Antonio; Monclús Lahoya, Eva; Brunet Crosa, Pere; Navazo Alvaro, Isabel; Vinacua Pla, Alvaro
    Graphical models
    Date of publication: 2012-11
    Journal article

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  • Haptics Illusion in Virtual Environments

     Brogni, Andrea
    Defense's date: 2011-12-19
    Department of Software, Universitat Politècnica de Catalunya
    Theses

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  • POINTING FACILITATION TECHNIQUES FOR 3D OBJECT SELECTION ON VIRTUAL ENVIRONMENTS  Open access

     Argelaguet Sanz, Fernando
    Defense's date: 2011-07-04
    Department of Software, Universitat Politècnica de Catalunya
    Theses

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    Les contribucions d’aquesta tesi s’emmarquen en la interacció home-computador en entorns de realitat virtual. Concretament, en la millora de tasques de selecció d’objectes tridimensionals. La selecció d’objectes és una tasca primordial en la interacció en entorns virtuals, doncs defineixen el curs de les accions de l’usuari envers l’entorn virtual. En aquesta tesi s’analitzen els factors que determinen l’eficiència de les tasques de selecció i es proposen millores en la seva usabilitat incrementant, tant la productivitat de l’usuari, com el seu confort. Al ser una tasca crítica, la seva millora és un factor prioritari. Les tasques de selecció en un entorn tridimensional requereixen la interacció mitjançant gestos, per exemple, agafar un objecte amb les mans o apuntar-lo amb el dit. L’efectivitat d’una tasca de selecció depèn de múltiples factors, com podria ser l’habilitat de l’usuari o en la percepció espacial de l’entorn. La tesi es centra en l’estudi de les limitacions de les tasques de selecció i de com els models d’interacció home-màquina existents, permeten el seu replantejament per a millorar la seva eficiència. Al llarg de la tesi es proposen diverses tècniques de selecció basades en la llei de Fitts, i s’analitza com evitar la dependència en la percepció espacial. Els anàlisis teòrics es complementen amb estudis d’usabilitat on s’avalua, tant l’efectivitat de les solucions proposades, com les ja existents. Encara que la major part de contribucions es centren en la selecció d’objectes tridimensionals, també s’estudia la selecció i manipulació d’interfícies gràfiques d’usuari 2D en entorns virtuals, i en la millora de la transferència d’informació entre usuaris en entorns col·laboratius. En aquests tipus d’entorns, és comú l’ús de la selecció per fer referència a determinats objectes o característiques del medi, a altres usuaris. No obstant, la impossibilitat de veure els objectes amb els què d’altres usuaris estan interactuant, dificulta l’intercanvi d’informació entre ells. S’ha fet un estudi de les eines utilitzades per a la gestió de l’oclusió i de com milloren l’intercanvi d’informació entre usuaris. Lloc i

    Les contribucions d’aquesta tesi s’emmarquen en la interacció home-computador en entorns de realitat virtual. Concretament, en la millora de tasques de selecció d’objectes tridimensionals. La selecció d’objectes és una tasca primordial en la interacció en entorns virtuals, doncs defineixen el curs de les accions de l’usuari envers l’entorn virtual. En aquesta tesi s’analitzen els factors que determinen l’eficiència de les tasques de selecció i es proposen millores en la seva usabilitat incrementant, tant la productivitat de l’usuari, com el seu confort. Al ser una tasca crítica, la seva millora és un factor prioritari. Les tasques de selecció en un entorn tridimensional requereixen la interacció mitjançant gestos, per exemple, agafar un objecte amb les mans o apuntar-lo amb el dit. L’efectivitat d’una tasca de selecció depèn de múltiples factors, com podria ser l’habilitat de l’usuari o en la percepció espacial de l’entorn. La tesi es centra en l’estudi de les limitacions de les tasques de selecció i de com els models d’interacció home-màquina existents, permeten el seu replantejament per a millorar la seva eficiència. Al llarg de la tesi es proposen diverses tècniques de selecció basades en la llei de Fitts, i s’analitza com evitar la dependència en la percepció espacial. Els anàlisis teòrics es complementen amb estudis d’usabilitat on s’avalua, tant l’efectivitat de les solucions proposades, com les ja existents. Encara que la major part de contribucions es centren en la selecció d’objectes tridimensionals, també s’estudia la selecció i manipulació d’interfícies gràfiques d’usuari 2D en entorns virtuals, i en la millora de la transferència d’informació entre usuaris en entorns col·laboratius. En aquests tipus d’entorns, és comú l’ús de la selecció per fer referència a determinats objectes o característiques del medi, a altres usuaris. No obstant, la impossibilitat de veure els objectes amb els què d’altres usuaris estan interactuant, dificulta l’intercanvi d’informació entre ells. S’ha fet un estudi de les eines utilitzades per a la gestió de l’oclusió i de com milloren l’intercanvi d’informació entre usuaris. Lloc i

  • Avances en realidad virtual para aplicaciones punteras

     Lligadas Rodriguez, Xavier; Susin Sanchez, Antonio; Brunet Crosa, Pere; Vinacua Pla, Alvaro; Fairen Gonzalez, Marta; Andujar Gran, Carlos A.; Monclús Lahoya, Eva; Vazquez Alcocer, Pere Pau; Campoalegre Vera, Lazaro; Argelaguet Sanz, Fernando; Pelechano Gomez, Nuria; Díaz Iriberri, José; Chica Calaf, Antonio; Cervero Abello, Maria Angels; Ojeda Contreras, Jesus; Beacco Porres, Alejandro; Navazo Alvaro, Isabel
    Participation in a competitive project

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  • Mesh repair with user-friendly topology control

     Hétroy, Franck; Rey, Stéphanie; Andujar Gran, Carlos A.; Brunet Crosa, Pere; Vinacua Pla, Alvaro
    Computer Aided Design
    Date of publication: 2011-01
    Journal article

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    Limitations of current 3D acquisition technology often lead to polygonal meshes exhibiting a number of geometrical and topological defects which prevent them from widespread use. In this paper we present a new method for model repair which takes as input an arbitrary polygonal mesh and outputs a valid 2-manifold triangle mesh. Unlike previous work, our method allows users to quickly identify areas with potential topological errors and to choose how to fix them in a user-friendly manner. Key steps of our algorithm include the conversion of the input model into a set of voxels, the use of morphological operators to allow the user to modify the topology of the discrete model, and the conversion of the corrected voxel set back into a 2-manifold triangle mesh. Our experiments demonstrate that the proposed algorithm is suitable for repairing meshes of a large class of shapes.

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    Volume-preserving deformation using generalized barycentric coordinates  Open access

     Cervero Abello, Maria Angels; Vinacua Pla, Alvaro; Brunet Crosa, Pere
    Congreso Español de Informática Gráfica
    Presentation's date: 2010-09
    Presentation of work at congresses

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    The cage-based deformation of a 3D object through generalized barycentric coordinates is a simple, e fficient, effective and hence widely used shape manipulation scheme. Editing vertices of the polyhedral cage induces a smooth space deformation of its interior; the vertices thus become control handles of the final deformation. However, in some application fi elds, as medicine, constrained volume preserving deformations are required. In this paper, we present a solution that takes advantage of the potential of the deformations based on generalized barycentric coordinates while adding the constraint of keeping a volume constant. An implementation of the proposed scheme is presented and discussed. A measure of local stress of the deformed volume is also proposed.

    Postprint (author’s final draft)

  • Visualization of large-scale urban models through multi-level relief impostors

     Andujar Gran, Carlos A.; Brunet Crosa, Pere; Chica Calaf, Antonio; Navazo Alvaro, Isabel
    Computer graphics forum
    Date of publication: 2010-12
    Journal article

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    In this paper, we present an efficient approach for the interactive rendering of large-scale urban models, which can be integrated seamlessly with virtual globe applications. Our scheme fills the gap between standard approaches for distant views of digital terrains and the polygonal models required for close-up views. Our work is oriented towards city models with real photographic textures of the building facades. At the heart of our approach is a multi-resolution tree of the scene defining multi-level relief impostors. Key ingredients of our approach include the pre-computation of a small set of zenithal and oblique relief maps that capture the geometry and appearance of the buildings inside each node, a rendering algorithm combining relief mapping with projective texture mapping which uses only a small subset of the pre-computed relief maps, and the use of wavelet compression to simulate two additional levels of the tree. Our scheme runs considerably faster than polygonal-based approaches while producing images with higher quality than competing relief-mapping techniques. We show both analytically and empirically that multi-level relief impostors are suitable for interactive navigation through large urban models.

  • Premio Nacional de Informática 2010

     Brunet Crosa, Pere
    Award or recognition

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  • Entre el método convencional y los sistemas innovadores de trabajo

     Brunet Crosa, Pere; Alonso, Fernando; Herrero, Javier; Torroja, Jaime
    Date of publication: 2009
    Book chapter

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  • GRUP DE RECERCA EN VISUALITZACIO, REALITAT VIRTUAL I INTERACCIO GRAFICA (VIRVIG)

     Vinacua Pla, Alvaro; Chica Calaf, Antonio; Díaz Iriberri, José; Vazquez Alcocer, Pere Pau; Susin Sanchez, Antonio; Monclús Lahoya, Eva; Andujar Gran, Carlos A.; Fairen Gonzalez, Marta; Cervero Abello, Maria Angels; Ojeda Contreras, Jesus; Lligadas Rodriguez, Xavier; Argelaguet Sanz, Fernando; Pelechano Gomez, Nuria; Campoalegre Vera, Lazaro; Navazo Alvaro, Isabel; Brunet Crosa, Pere
    Participation in a competitive project

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  • Dynamic Terrains: Cities and Real-Time Video on Gigantic Terrain Models

     Andujar Gran, Carlos A.; Brunet Crosa, Pere; Díaz Iriberri, José
    Geographical Information Processing and Visual Analytics for Environmental Security NATO - ADVANCED RESEARCH WORKSHOP
    Presentation of work at congresses

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    La realidad virtual en el aprendizaje de historia mediante la interacción con humanoides virtuales  Open access

     Muñoz, Albert; Besora, Isaac; Creus Lopez, Carles; Pelechano Gomez, Nuria; Brunet Crosa, Pere; Beacco Porres, Alejandro
    Jornadas sobre Realidad Virtual y Entornos Virtuales
    Presentation's date: 2009-09-07
    Presentation of work at congresses

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    La realidad virtual ofrece la posibilidad de interactuar de manera inmersiva en mundos virtuales 3D. Estos mundos virtuales pueden ser representaciones de otros momentos históricos que permiten al usuario explorar los modelos virtuales como si de una visita turística al pasado se tratase. En este proyecto se ha realizado una reconstrucción virtual de la antigua ciudad romana de Tarragona (Tarraco) para ofrecer un entorno interactivo en el que los visitantes a la exposición puedan navegar por diferentes partes de la ciudad así como interactuar con humanoides virtuales representando romanos que ayudarán al usuario a recopilar información histórica y aprender mediante un sencillo juego interactivo.

    Postprint (author’s final draft)

  • Massive mesh hole repair minimizing user intervention

     Brunet Crosa, Pere; Chica Calaf, Antonio; Navazo Alvaro, Isabel; Vinacua Pla, Alvaro
    Computing
    Date of publication: 2009-10
    Journal article

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    Piecewise algebraic surface computation and smoothing from a discrete model  Open access

     Esteve Cusine, Jordi; Vinacua Pla, Alvaro; Brunet Crosa, Pere
    Computer aided geometric design
    Date of publication: 2008-08
    Journal article

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    This paper describes a contrained fairing method for implicit surfaces defined on a voxelization. This method is suitable for computing a closed smooth surface that approximates an initial set of face connected

  • Pressing: Smooth Isosurfaces with Flats from Binary Grids

     Chica Calaf, Antonio; Williams, J; Andujar Gran, Carlos A.; Brunet Crosa, Pere; Navazo Alvaro, Isabel; Rossignac, J; Vinacua Pla, Alvaro
    Computer graphics forum
    Date of publication: 2008-01
    Journal article

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  • The distinguished Career Award

     Brunet Crosa, Pere
    Award or recognition

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  • Real-time exploration of the virtual reconstruction of the entrance of the Ripoll Monastery

     Besora, Isaac; Brunet Crosa, Pere; Chica Calaf, Antonio; Morales, Daniel; Moyés, Jordi
    Congreso Español de Informática Gráfica
    Presentation's date: 2008
    Presentation of work at congresses

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    Relief impostor selection for large scale urban rendering  Open access

     Andujar Gran, Carlos A.; Díaz Iriberri, José; Brunet Crosa, Pere
    IEEE Virtual Reality Workshop on Virtual Cityscapes: Key Research Issues in Modeling Large-Scale Immersive Urban Environments
    Presentation's date: 2008-03-08
    Presentation of work at congresses

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    Image-based rendering techniques are often the preferred choice to accelerate the exploration of massive outdoor models and complex human-made structures. In the last few years, relief mapping has been shown to be extremely useful as a compact representation of highly-detailed 3D models. In this paper we describe a rendering system for interactive, high-quality visualization of large scale urban models through a hierarchical collection of properly-oriented relief-mapped polygons. At the heart of our approach is a visibilityaware algorithm for the selection of the set of viewing planes supporting the relief maps. Our selection algorithm optimizes both the sampling density and the coverage of the relief maps and its running time is mostly independent on the underlying geometry. We show that our approach is suitable for navigating through large scale urban models at interactive rates while preserving both geometric and appearance details.

  • A comparison among three low cost VR systems

     Brunet Crosa, Pere; Fairen Gonzalez, Marta; Moyés, J
    Jornadas sobre Realidad Virtual y Entornos Virtuales
    Presentation of work at congresses

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  • Portalada: a virtual reconstruction of the entrance of the Ripoll Monastery

     Besora, Isaac; Brunet Crosa, Pere; Callieri, Marco; Chica Calaf, Antonio; Corsini, Massimiliano; Dellepiane, Matteo; Morales, Daniel; Moyés, Jordi; Ranzuglia, Guido; Scopigno, Roberto
    International Symposium on 3D Data Processing, Visualization and Transmission
    Presentation's date: 2008
    Presentation of work at congresses

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    The dichotomy between detail representation and data management is still a big issue in the context of the acquisition and visualization of 3D objects, especially in the field of Cultural Heritage. New technologies give the possibility to acquire very detailed geometry, but very often it’s very hard to process the amount of data produced. In this paper we present a project which aimed at virtually reconstructing the impressive (7x11 m.) portal of the Ripoll Monastery, Spain. The monument was acquired using triangulation laser scanning technology, producing a dataset of more than 2000 range maps for a total of more than 1 billion triangles. All the steps of the entire project are described, from the acquisition planning to the final setup for the dissemination to the public. In particular, we show how timeof-flight laser scanning data can be used to obtain a speed up in the alignment process, and how, after model creation and imperfections repairing, an interactive and immersive setup gives the public the possibility to navigate and visualize the high detail representation of the portal. This paper shows that, after careful planning and with the aim of new algorithms, it’s now possible to preserve and visualize the highly detailed information provided by triangulation laser scanning also for very large surfaces.

  • Omni-directional relief impostors

     Andujar Gran, Carlos A.; Boo, J; Brunet Crosa, Pere; Fairen Gonzalez, Marta; Navazo Alvaro, Isabel; Vazquez Alcocer, Pere Pau; Vinacua Pla, Alvaro
    Computer graphics forum
    Date of publication: 2007-07
    Journal article

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  • Buque Autónomo Polivalente para la Pesca 2020 (BAIP 2020)

     González Blanco, Ricardo; Garcia Espinosa, Julio; Mari Sagarra, Ricardo; Brunet Crosa, Pere; Vinacua Pla, Alvaro; Navazo Alvaro, Isabel
    Participation in a competitive project

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  • Modelling Very Complex Assemblies: The Use of Discrete and Hierarchical Models

     Brunet Crosa, Pere; Navazo Alvaro, Isabel; Vinacua Pla, Alvaro
    Computer-aided design and applications
    Date of publication: 2006-06
    Journal article

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  • IST-027731 PRESENCCIA coordinació

     Slater, Melvyn; Navazo Alvaro, Isabel; Brunet Crosa, Pere; Vinacua Pla, Alvaro; Andujar Gran, Carlos A.
    Participation in a competitive project

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  • Pressing: Smooth Isosurfaces with Flats from Binary Grids

     Andujar Gran, Carlos A.; Brunet Crosa, Pere; Navazo Alvaro, Isabel; Vinacua Pla, Alvaro
    Date: 2006-02
    Report

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    A topological comparison of surface extraction algorithms  Open access

     Andujar Gran, Carlos A.; Brunet Crosa, Pere; Fairen Gonzalez, Marta; Navazo Alvaro, Isabel; Vinacua Pla, Alvaro
    Date: 2006-01
    Report

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    In many application areas, it is useful to convert the discrete information stored in the nodes of a regular grid into a continuous boundary model. Isosurface extraction algorithms di er on how the discrete information in the grid is generated, on what information does the grid store and on the properties of the output surface.

  • Approximation of a variable density cloud of points by shrinking a discrete membrane

     Esteve Cusine, Jordi; Brunet Crosa, Pere; Vinacua Pla, Alvaro
    Computer graphics forum
    Date of publication: 2005-12
    Journal article

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    This paper describes a method to obtain a closed surface that approximates a general 3D data point set with nonuniform density. Aside from the positions of the initial data points, no other information is used. Particularly, neither the topological relations between the points nor the normal to the surface at the data points are needed. The reconstructed surface does not exactly interpolate the initial data points, but approximates them with a bounded maximum distance. The method allows one to reconstruct closed surfaces with arbitrary genus and closed surfaces with disconnected shells

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    Optimizing the topological and combinatorial complexity of isosurfaces  Open access

     Andujar Gran, Carlos A.; Brunet Crosa, Pere; Chica Calaf, Antonio; Navazo Alvaro, Isabel; Rossignac, Jarek; Vinacua Pla, Alvaro
    Computer Aided Design
    Date of publication: 2005-07
    Journal article

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    Since the publication of the original Marching Cubes algorithm, numerous variations have been proposed for guaranteeing water-tight constructions of triangulated approximations of isosurfaces. Most approaches divide the 3D space into cubes that each occupy the space between eight neighboring samples of a regular lattice. The portion of the isosurface inside a cube may be computed independently of what happens in the other cubes, provided that the constructions for each pair of neighboring cubes agree along their common face. The portion of the isosurface associated with a cube may consist of one or more connected components, which we call sheets. The topology and combinatorial complexity of the isosurface is influenced by three types of decisions made during its construction: (1) how to connect the four intersection points on each ambiguous face, (2) how to form interpolating sheets for cubes with more than one loop, and (3) how to triangulate each sheet. To determine topological properties, it is only relevant whether the samples are inside or outside the object, and not their precise value, if there is one. Previously reported techniques make these decisions based on local —per cube— criteria, often using precomputed look-up tables or simple construction rules. Instead, we propose global strategies for optimizing several topological and combinatorial measures of the isosurfaces: triangle count, genus, and number of shells. We describe efficient implementations of these optimizations and the auxiliary data structures developed to support them.

  • Hierarchical model for pipe design and editing

     Surinyac, Jordi; Brunet Crosa, Pere
    Congreso Español de Informática Gráfica
    Presentation's date: 2005
    Presentation of work at congresses

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  • Error-Bounded Simplification of Topologically-Complex Assemblies

     Andujar Gran, Carlos A.; Brunet Crosa, Pere; Fairen Gonzalez, Marta; Cebollada, V
    Date of publication: 2005-01
    Book chapter

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  • TIN2004-20255-E

     Brunet Crosa, Pere
    Participation in a competitive project

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  • Minimizing isosurface area

     Iordache, Costin; Brunet Crosa, Pere
    Congreso Español de Informática Gráfica
    Presentation's date: 2005
    Presentation of work at congresses

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  • Use of Augmented Reality in treatment of vision defects

     Rodriguez, J.; Brunet Crosa, Pere; Ezquerra, N.
    Date: 2005-09
    Report

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    Piecewise algebraic surface computation and fairing from a discrete model  Open access

     Esteve Cusine, Jordi; Vinacua Pla, Alvaro; Brunet Crosa, Pere
    Date: 2005-10
    Report

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    This paper describes a constrained fairing method for implicit surfaces defined on a voxelization. This method is suitable for computing a closed smooth surface that approximates an initial set of face connected voxels.

  • A Virtual Reality approach to progressive lenses simulation

     Rodríguez Celaya, Jose Antonio; Brunet Crosa, Pere; Ezquerra, Norberto; Palomar, J.E.
    Congreso Español de Informática Gráfica
    Presentation's date: 2005-09
    Presentation of work at congresses

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  • Computing maximal tiles and application to impostor-based simplification

     Andujar Gran, Carlos A.; Brunet Crosa, Pere; Chica Calaf, Antonio; Navazo Alvaro, Isabel; Rossignac, J; Vinacua Pla, Alvaro
    Computer graphics forum
    Date of publication: 2004-08
    Journal article

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    The computation of the largest planar region approximating a 3D object is an important problem with wide applications in modeling and rendering. Given a voxelization of the 3D object, we propose an efficient algorithm to solve a discrete version of this problem. The input of the algorithm is the set of grid edges connecting the interior and the exterior of the object (called sticks). Using a voting-based approach, we compute the plane that slices the largest number of sticks and is orientation-compatible with these sticks. The robustness and efficiency of our approach rests on the use of two different parameterizations of the planes with suitable properties. The first of these is exact and is used to retrieve precomputed local solutions of the problem. The second one is discrete and is used in a hierarchical voting scheme to compute the global maximum. This problem has diverse applications that range from finding object signatures to generating simplified models. Here we demonstrate the merits of the algorithm for efficiently computing an optimized set of textured impostors for a given polygonal model.

  • MiniVR: a portable virtual reality system

     Fairen Gonzalez, Marta; Brunet Crosa, Pere; Techmann, Torsten
    Computers & graphics
    Date of publication: 2004-04
    Journal article

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  • Collision Detection in Large Environments using Multiresolution KdTrees

     Franquesa Niubo, Marta
    Defense's date: 2004-05-05
    Department of Software, Universitat Politècnica de Catalunya
    Theses

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    Optimal iso-surfaces  Open access

     Andujar Gran, Carlos A.; Brunet Crosa, Pere; Chica Calaf, Antonio; Navazo Alvaro, Isabel; Rossignac, Jarek; Vinacua Pla, Alvaro
    Computer-aided design and applications
    Date of publication: 2004-05
    Journal article

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    Since the publication of the original Marching Cubes algorithm, numerous variations have been proposed for guaranteeing water-tight constructions of triangulated approximations of iso-surfaces. Most approaches divide the 3D space into cubes that each occupies the space between eight neighboring samples of a regular lattice. The portion of the iso-surface inside a cube may be computed independently of what happens in the other cubes, provided that the constructions for each pair of neighboring cubes agree along their common face. The portion of the iso-surface associated with a cube may consist of one or more connected components, which we call sheets. We distinguish three types of decisions in the construction of the iso-surface connectivity: (1) how to split the X-faces, which have alternating in/out samples, (2) how many sheets to use in a cube, and (3) how to triangulate each sheet. Previously reported techniques make these decisions based on local criteria, often using pre-computed look-up tables or simple construction rules. Instead, we propose global strategies for optimizing several topological and combinatorial measures of the isosurfaces: triangle count, genus, and number of shells. We describe efficient implementations of these optimizations and the auxiliary data structures developed to support them.

  • Solid Modeling and Applications

     Gershon, Elber; Patrikalakis, Nick; Brunet Crosa, Pere
    Date of publication: 2004-06
    Book

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  • TIN2004-08065-C02-01 INTERFACES AVANZADAS PARA LA INTERACION TRANSPARENTE CON MODELOS ALTAMENTE COMPLEJOS EN ENTORNOS DE REALIDAD VI

     Navazo Alvaro, Isabel; Brunet Crosa, Pere; Susin Sanchez, Antonio
    Participation in a competitive project

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  • Collision prediction using MKtrees

     Franquesa Niubo, Marta; Brunet Crosa, Pere
    Winter School on Computer Graphics
    Presentation's date: 2004-02-03
    Presentation of work at congresses

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  • On the Selection of Good Views and its Application To Computer Graphics  awarded activity

     Vazquez Alcocer, Pere Pau
    Defense's date: 2003-05-26
    Department of Software, Universitat Politècnica de Catalunya
    Theses

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  • Collision Detection using Multiresolution KdTrees

     Franquesa Niubo, Marta; Brunet Crosa, Pere
    XIII Congreso Español de Informática Gràfica
    Presentation of work at congresses

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  • Robust Face Recovery for Hybrid Surface Visualization

     Andujar Gran, Carlos A.; Brunet Crosa, Pere; Esteve Cusine, Jordi; Monclús Lahoya, Eva; Navazo Alvaro, Isabel; Vinacua Pla, Alvaro
    Vision Modeling and Visualization 2003
    Presentation of work at congresses

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  • Error-bounded simplification of topologically-complex assemblies

     Andujar Gran, Carlos A.; Fairen Gonzalez, Marta; Brunet Crosa, Pere; Cebollada, V
    4th Workshop on Multiresolution and Geometric Modelling
    Presentation of work at congresses

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