Modelado de terrenos para dispositivos móviles

El modelado de terrenos es un elemento importante en la representación de muchas escenas virtuales. A menudo, los terrenos son representados en base a grandes conjuntos de datos, lo cual es un punto importante a tener en cuenta cuando se hace el renderizado para un dispositivo móvil. Dentro del ámbito de las PCs, una de las técnicas más usadas para la representación de terrenos irregulares es conocida como TINs (Triangulated Irregular Networks) pues permite hacer un seguimiento fiel a las variaciones que posee un terreno. Cabe destacar que la aplicación de la técnica por si sola no es viable para el modelado en un dispositivo móvil por las limitaciones que posee tal dispositivo. Es por esto que en este trabajo se llevó a cabo el estudio de un modelo de datos de terrenos adecuado para los dispositivos móviles y actualmente se está desarrollando una alternativa viable para los mismos.Eje: Computación gráfica, imágenes y visualizaciónRed de Universidades con Carreras en Informática (RedUNCI

Modelado de terrenos para dispositivos móviles

El modelado de terrenos es un elemento importante en la representación de muchas escenas virtuales. A menudo, los terrenos son representados en base a grandes conjuntos de datos, lo cual es un punto importante a tener en cuenta cuando se hace el renderizado para un dispositivo móvil. Dentro del ámbito de las PCs, una de las técnicas más usadas para la representación de terrenos irregulares es conocida como TINs (Triangulated Irregular Networks) pues permite hacer un seguimiento fiel a las variaciones que posee un terreno. Cabe destacar que la aplicación de la técnica por si sola no es viable para el modelado en un dispositivo móvil por las limitaciones que posee tal dispositivo. Es por esto que en este trabajo se llevó a cabo el estudio de un modelo de datos de terrenos adecuado para los dispositivos móviles y actualmente se está desarrollando una alternativa viable para los mismos.Eje: Computación gráfica, imágenes y visualizaciónRed de Universidades con Carreras en Informática (RedUNCI

Modelado de terrenos para dispositivos móviles

El modelado de terrenos es un elemento importante en la representación de muchas escenas virtuales. A menudo, los terrenos son representados en base a grandes conjuntos de datos, lo cual es un punto importante a tener en cuenta cuando se hace el renderizado para un dispositivo móvil. Dentro del ámbito de las PCs, una de las técnicas más usadas para la representación de terrenos irregulares es conocida como TINs (Triangulated Irregular Networks) pues permite hacer un seguimiento fiel a las variaciones que posee un terreno. Cabe destacar que la aplicación de la técnica por si sola no es viable para el modelado en un dispositivo móvil por las limitaciones que posee tal dispositivo. Es por esto que en este trabajo se llevó a cabo el estudio de un modelo de datos de terrenos adecuado para los dispositivos móviles y actualmente se está desarrollando una alternativa viable para los mismos.Eje: Computación gráfica, imágenes y visualizaciónRed de Universidades con Carreras en Informática (RedUNCI

A Framework for Dynamic Terrain with Application in Off-road Ground Vehicle Simulations

The dissertation develops a framework for the visualization of dynamic terrains for use in interactive real-time 3D systems. Terrain visualization techniques may be classified as either static or dynamic. Static terrain solutions simulate rigid surface types exclusively; whereas dynamic solutions can also represent non-rigid surfaces. Systems that employ a static terrain approach lack realism due to their rigid nature. Disregarding the accurate representation of terrain surface interaction is rationalized because of the inherent difficulties associated with providing runtime dynamism. Nonetheless, dynamic terrain systems are a more correct solution because they allow the terrain database to be modified at run-time for the purpose of deforming the surface. Many established techniques in terrain visualization rely on invalid assumptions and weak computational models that hinder the use of dynamic terrain. Moreover, many existing techniques do not exploit the capabilities offered by current computer hardware. In this research, we present a component framework for terrain visualization that is useful in research, entertainment, and simulation systems. In addition, we present a novel method for deforming the terrain that can be used in real-time, interactive systems. The development of a component framework unifies disparate works under a single architecture. The high-level nature of the framework makes it flexible and adaptable for developing a variety of systems, independent of the static or dynamic nature of the solution. Currently, there are only a handful of documented deformation techniques and, in particular, none make explicit use of graphics hardware. The approach developed by this research offloads extra work to the graphics processing unit; in an effort to alleviate the overhead associated with deforming the terrain. Off-road ground vehicle simulation is used as an application domain to demonstrate the practical nature of the framework and the deformation technique. In order to realistically simulate terrain surface interactivity with the vehicle, the solution balances visual fidelity and speed. Accurately depicting terrain surface interactivity in off-road ground vehicle simulations improves visual realism; thereby, increasing the significance and worth of the application. Systems in academia, government, and commercial institutes can make use of the research findings to achieve the real-time display of interactive terrain surfaces

Métricas para simplificaçao de malhas triangulares

Orientador: Hélio PedriniDissertaçao (mestrado) - Universidade Federal do Paraná, Setor de Ciencias Exatas, Programa de Pós-Graduaçao em Informática. Defesa: Curitiba, 2005Inclui bibliografia e apendiceResumo: Malhas triangulares são uma das representações de dados espaciais mais utilizadas, pois possibilitam a manipulação e visualização de superfícies de alta complexidade, além de apresentarem diversas vantagens, como suporte direto em software e hardware. O problema de como transformar conjuntos de dados espaciais distintos, entre eles modelos de terrenos, conjuntos de pontos tridimensionais e dados volumétricos, em malhas triangulares é amplamente estudado. Além disso, com o aumento da capacidade de coleta desse tipo de dados, torna-se cada vez mais comum a necessidade de manipulação de modelos com altíssima resolução. Uma abordagem para a solução desses dois problemas é a simplificação de malhas triangulares. Esta consiste em primeiramente transformar um determinado conjunto de dados em uma malha triangular e, então, simplificá-la reduzindo-se o número de vértices, arestas e triângulos, de forma que a malha simplificada aproxime a malha original com o menor erro possível. Assim, torna-se possível manipular os dados em questão e, aplicando-se o método de simplificação repetidamente com diferentes requisitos de qualidade, obtêm-se representações da malha triangular em diversas resoluções. Dentro do âmbito da simplificação de malhas triangulares, este trabalho se propõe a verificar experimentalmente quais métricas de caráter local existentes na literatura possibilitam uma simplificação rápida e gerando aproximações de alta qualidade. Além disso, este trabalho também propõe duas novas métricas que geram aproximações de grande qualidade e são uma alternativa mais adequada para certas aplicações. Outros aspectos dos métodos de simplificação de malhas triangulares também são investigados, bem como o seu efeito na qualidade das aproximações geradas. Para que as diferentes opções do método de simplificação pudessem ser investigadas sem a interferência de implementações distintas, um programa para a simplificação de malhas triangulares foi implementado, de forma que o resultado da mudança de apenas opções específicas do método de simplificação é adequadamente verificado. Também são discutidos os diversos trabalhos da literatura que utilizam as operações de simplificação para a construção de uma representação em múltiplas resoluções, da qual 'e possível então extrair uma malha triangular com determinado nível de detalhe, sem a necessidade da aplicação de um método de simplificação.Abstract: Triangle meshes are one of the mostly employed spatial data representations, since they allow the manipulation and visualization of highly complex surfaces, apart from presenting many advantages, including direct software and hardware support. The problem of converting distinct spatial datasets, among them terrain models, tridimensional point sets, and volumetric data, into triangle meshes is widely studied. Furthermore, with the increase in the collection capacity of such type of data, the manipulation of models with high resolution has become a common task. One approach for the solution of these two problems is triangle mesh simplification, which consists in firstly converting a specific dataset into a triangle mesh and then simplifying it to reduce the number of vertices, edges, and faces, in a way that the simplified mesh approximates the original mesh with the lowest error. Therefore, it is possible to manipulate the data and, by applying repeatedly the simplification method with different quality requirements, a representation in multiple resolutions is obtained. In the scope of triangle mesh simplification, this work presents an experimental study to establish which local metrics that exist in the literature allow fast simplification generating high quality approximations. This work also proposes two new metrics that are an adequate alternative for certain applications, and also generate great quality approximations. Other aspects of triangle mesh simplification are also studied, including their impact in the quality of the approximations. For the investigation of the different options of the simplification method, without the interference of distinct implementations, a program for triangle mesh simplification was implemented, allowing that the change in specific simplification options can be properly verified. Different works from the literature are also discussed, that employ the simplification operations for the creation of a multi-resolution representation, from which it is possible to extract a triangle mesh with a required level of detail, without the necessity of applying a simplification method

Multiskalenmethoden zur Kompression und interaktiven Verarbeitung großer Datenmengen

Die vorliegende Arbeit beschaeftigt sich mit der Entwicklung von Verfahren zur interaktiven graphischen Darstellung (Visualisierung) grosser Datenmengen. Insbesondere betrifft dies adaptiv hierarchische Verfahren zur Darstellung von Oberflaechen und Isolinien, sowie zur Schnittbildung, Isoflaechen- Extraktion und Volumendarstellung. Zum einen wird die Berechnung von Fehlerindikatoren und Fehlerschranken zur Steuerung der adaptiven Verfeinerung, insbesondere Saturierungstechniken zur Vermeidung haengender Knoten und Berechnung von minmax-Schranken, zur Fokussierung, sowie zur Topologie-Erhaltung und kontrollierten Topologie- Vereinfachung betrachtet. Weiterhin werden Kompressionsverfahren basierend auf Wavelets mit Hilfe des lifting Schemas, sowie raumfuellenden Kurven und relativen Sprungzeigern fuer hierarchische Triangulierungen entwickelt. Schliesslich wird die Beschleunigung der Visualisierungsalgorithmen durch Parallelisierung am Beispiel der Isoflaechen-Extraktion, sowie durch hierarchische Sortierung bei der Darstellung mehrerer transparenter Isoflaechen untersucht. Die Anwendungsgebiete der Verfahren liegen dabei in den Bereichen GIS, Meteorologie, Bildkompression, medizinische Bildverarbeitung und Chemie.This work is concerned with the development of methods for the interactive visualization of large data sets. Of special concern are adaptive hierarchical methods for the respresentation of surfaces, isolines, slicing, isosurface extraction and volume rendering. One major focus is the computation of error indicators and error bounds to guide the adaptive refinement. This especially concerns saturation techniques for the preventon of hanging nodes, for the computation of minmax bounds, for focussing, and for topology preservation and controlled topology simplification. The second emphasis are compression methods based on wavelets using the lifting scheme as well as space-filling curves and relative branch pointers for hierarchical triangulations. Furthermore, the acceleration of the visualization algorithms by parallelization for example in isosurface extraction and hierarchical sorting for the rendering of multiple transparent isosurfaces is considered. The application areas of the presented methods are geographical information systems, meteorology, image compression, medical imaging, and chemistry

Hydrologic modeling using triangulated irregular networks : terrain representation, flood forecasting and catchment response

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2003.Includes bibliographical references.Numerical models are modern tools for capturing the spatial and temporal variability in the land-surface hydrologic response to rainfall and understanding the physical relations between internal watershed processes and observed streamflow. This thesis presents the development and application of a distributed hydrologic model distinguished by its representation of topography through a triangulated irregular network (TIN) and its coupling of the surface and subsurface processes leading to the catchment response. As a research tool for hydrologic forecasting and experimentation, the TIN-based Real-time Integrated Basin Simulator (tRIBS) fully incorporates spatial heterogeneities in basin topography, surface descriptors and hydrometeorological forcing to produce dynamic maps of hydrologic states and fluxes. These capabilities allow investigation of theoretical questions and practical problems in hydrologic science and water resources engineering. Three related themes are developed in this thesis. First, a set of methods are developed for constructing TIN topographic models from raster digital elevation models (DEM) for hydrologic and geomorphic applications. A new approach for representing a steady-state estimate of a particular watershed process within the physical mesh is introduced. Hydrologic comparisons utilizing different terrain models are made to investigate the suitable level of detail required for capturing process dynamics accurately. Second, the TIN-based model is utilized in conjunction with a rainfall forecasting algorithm to assess the space-time flood predictability. For two hydrometeorological case studies, the forecast skill is assessed as a function of rainfall forecast lead time, catchment scale and the spatial variability in the quantitative precipitation forecasts (QPF). Third, the surface and subsurface runoff response in a complex basin is investigated with respect to changes in storm properties and the initial water table position.The partitioning of rainfall into runoff production mechanisms is found to be a causative factor in the nonlinearity and scale-dependence observed in the basin hydrograph response. The model applications presented in this thesis highlight the advantages of TIN- based modeling for hydrologic forecasting and process-oriented studies over complex terrain. In particular, the multi-resolution and multi-scale capabilities are encouraging for a range of applied and scientific problems in catchment hydrology.by Enrique R. Vivoni.Ph.D