442 research outputs found
Procedural textures generation: adaptation into a Unity tool
This is a description document that explains the procedure and development of the “Procedural Texture Generator” tool for Unity. It is a node-based editor that allows the user to create textures by generating different types of noises, combining them, and using several filters to generate the different textures needed for PBR materials. In this document there are described the techniques and procedures used for procedural texturing and the adaptation into a Unity tool, as well as all the difficulties encountered during the development
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Surface Splatting
Modern laser range and optical scanners need rendering techniques that can handle millions of points with high resolution textures. This paper describes a point rendering and texture filtering technique called surface splatting which directly renders opaque and transparent surfaces from point clouds without connectivity. It is based on a novel screen space formulation of the Elliptical Weighted Average (EWA) filter. Our rigorous mathematical analysis extends the texture resampling framework of Heckbert to irregularly spaced point samples. To render the points, we develop a surface splat primitive that implements the screen space EWA filter. Moreover, we show how to optimally sample image and procedural textures to irregular point data during pre-processing. We also compare the optimal algorithm with a more efficient view-independent EWA pre-filter. Surface splatting makes the benefits of EWA texture filtering available to point-based rendering. It provides high quality anisotropic texture filtering, hidden surface removal, edge anti-aliasing, and order-independent transparency.Engineering and Applied Science
Real-time tessellation of terrain on graphics hardware
Synthetic terrain is a key element in many applications, which can lessen the sense of realism if it is not handled correctly. We propose a new technique for visualizing terrain surfaces by tessellating them on the GPU. The presented algorithm introduces a new adaptive tessellation scheme for managing the level of detail of the terrain mesh, avoiding the appearance of t-vertices that can produce visually disturbing artifacts. Previous solutions exploited the geometry shader's capabilities to tessellate meshes from scratch. In contrast, we reuse the already calculated data to minimize the operations performed in the shader units. This feature allows us to increase performance through smart refining and coarsening. Finally, we also propose a framework to manage large DEMs as height maps.This work has been supported by the Spanish Ministry of Science and Technology (projects TIN2009-14103-C03-03, TSI-020400-2009-0133 and TIN2010-21089-C03-03), by the Generalitat Valenciana (project PROMETEO/2010/028), by Bancaja (project P1 1B2010-08) and by ITEA2 (project IP08009
Multiresolution Techniques for Real–Time Visualization of Urban Environments and Terrains
In recent times we are witnessing a steep increase in the availability of data coming from real–life environments.
Nowadays, virtually everyone connected to the Internet may have instant access to a tremendous amount of data coming from satellite elevation maps, airborne time-of-flight scanners and digital cameras, street–level photographs and even cadastral maps.
As for other, more traditional types of media such as pictures and videos, users of digital exploration softwares expect commodity hardware to exhibit good performance for interactive purposes, regardless of the dataset size.
In this thesis we propose novel solutions to the problem of rendering large terrain and urban models on commodity platforms, both for local and remote exploration.
Our solutions build on the concept of multiresolution representation, where alternative representations of the same data with different accuracy are used to selectively distribute the computational power, and consequently the visual accuracy, where it is more needed on the base of the user’s point of view.
In particular, we will introduce an efficient multiresolution data compression technique for planar and spherical surfaces applied to terrain datasets which is able to handle huge amount of information at a planetary scale.
We will also describe a novel data structure for compact storage and rendering of urban entities such as buildings to allow real–time exploration of cityscapes from a remote online repository.
Moreover, we will show how recent technologies can be exploited to transparently integrate virtual exploration and general computer graphics techniques with web applications
Shallow waters simulation
Dissertação de mestrado integrado em Informatics EngineeringRealistic simulation and rendering of water in real-time is a challenge within the field of computer graphics, as it
is very computationally demanding. A common simulation approach is to reduce the problem from 3D to 2D by
treating the water surface as a 2D heightfield. When simulating 2D fluids, the Shallow Water Equations (SWE)
are often employed, which work under the assumption that the water’s horizontal scale is much greater than it’s
vertical scale.
There are several methods that have been developed or adapted to model the SWE, each with its own advantages
and disadvantages. A common solution is to use grid-based methods where there is the classic approach
of solving the equations in a grid, but also the Lattice-Boltzmann Method (LBM) which originated from the field of
statistical physics. Particle based methods have also been used for modeling the SWE, namely as a variation of
the popular Smoothed-Particle Hydrodynamics (SPH) method.
This thesis presents an implementation for real-time simulation and rendering of a heightfield surface water
volume. The water’s behavior is modeled by a grid-based SWE scheme with an efficient single kernel compute
shader implementation.
When it comes to visualizing the water volume created by the simulation, there are a variety of effects that
can contribute to its realism and provide visual cues for its motion. In particular, When considering shallow water,
there are certain features that can be highlighted, such as the refraction of the ground below and corresponding
light attenuation, and the caustics patterns projected on it.
Using the state produced by the simulation, a water surface mesh is rendered, where set of visual effects are
explored. First, the water’s color is defined as a combination of reflected and transmitted light, while using a Cook-
Torrance Bidirectional Reflectance Distribution Function (BRDF) to describe the Sun’s reflection. These results
are then enhanced by data from a separate pass which provides caustics patterns and improved attenuation
computations. Lastly, small-scale details are added to the surface by applying a normal map generated using
noise.
As part of the work, a thorough evaluation of the developed application is performed, providing a showcase of
the results, insight into some of the parameters and options, and performance benchmarks.Simulação e renderização realista de água em tempo real é um desafio dentro do campo de computação gráfica,
visto que é muito computacionalmente exigente. Uma abordagem comum de simulação é de reduzir o problema
de 3D para 2D ao tratar a superfície da água como um campo de alturas 2D. Ao simular fluidos em 2D, é
frequente usar as equações de águas rasas, que funcionam sobre o pressuposto de que a escala horizontal da
água é muito maior que a sua escala vertical.
Há vários métodos que foram desenvolvidos ou adaptados para modelar as equações de águas rasas, cada
uma com as suas vantagens e desvantagens. Uma solução comum é utilizar métodos baseados em grelhas
onde existe a abordagem clássica de resolver as equações numa grelha, mas também existe o método de Lattice
Boltzmann que originou do campo de física estatística. Métodos baseados em partículas também já foram
usados para modelar as equações de águas rasas, nomeadamente como uma variação do popular método de
SPH.
Esta tese apresenta uma implementação para simulação e renderização em tempo real de um volume de
água com uma superfície de campo de alturas. O comportamento da água é modelado por um esquema de
equações de águas rasas baseado na grelha com uma implementação eficiente de um único kernel de compute
shader.
No que toca a visualizar o volume de água criado pela simulação, existe uma variedade de efeitos que podem
contribuir para o seu realismo e fornecer dicas visuais sobre o seu movimento. Ao considerar águas rasas, existem
certas características que podem ser destacadas, como a refração do terreno por baixo e correspondente
atenuação da luz, e padrões de cáusticas projetados nele.
Usando o estado produzido pela simulação, uma malha da superfície da água é renderizada, onde um conjunto
de efeitos visuais são explorados. Em primeiro lugar, a cor da água é definida como uma combinação de
luz refletida e transmitida, sendo que uma BRDF de Cook-Torrance é usada para descrever a reflexão do Sol.
Estes resultados são depois complementados com dados gerados num passo separado que fornece padrões
de cáusticas e melhora as computações de atenuação. Por fim, detalhes de pequena escala são adicionados à
superfície ao aplicar um mapa de normais gerado com ruído.
Como parte do trabalho desenvolvido, é feita uma avaliação detalhada da aplicação desenvolvida, onde é apresentada
uma demonstração dos resultados, comentários sobre alguns dos parâmetros e opções, e referências
de desempenho
Actas do 10º Encontro Português de Computação Gráfica
Actas do 10º Encontro Portugês de Computação Gráfica, Lisboa, 1-3 de Outubro de 2001A investigação, o desenvolvimento e o ensino na área da Computação Gráfica constituem, em Portugal, uma realidade positiva e de largas tradições. O Encontro Português de Computação Gráfica (EPCG), realizado no âmbito das actividades do Grupo Português de Computação Gráfica (GPCG), tem permitido reunir regularmente, desde o 1º EPCG
realizado também em Lisboa, mas no já longínquo mês de Julho de 1988, todos os que trabalham nesta área abrangente
e com inúmeras aplicações.
Pela primeira vez no historial destes Encontros, o 10º EPCG foi organizado em ligação estreita com as comunidades do
Processamento de Imagem e da Visão por Computador, através da Associação Portuguesa de Reconhecimento de Padrões (APRP), salientando-se, assim, a acrescida colaboração, e a convergência, entre essas duas áreas e a Computação Gráfica. Este é o livro de actas deste 10º EPCG.INSATUniWebIcep PortugalMicrografAutodes
Anisotropic noise
Programmable graphics hardware makes it possible to generate procedural noise textures on the fly for interactive rendering. However, filtering and antialiasing procedural noise involves a tradeoff between aliasing artifacts and loss of detail. In this paper we present a technique, targeted at interactive applications, that provides high-quality anisotropic filtering for noise textures. We generate noise tiles directly in the frequency domain by partitioning the frequency domain into oriented subbands. We then compute weighted sums of the subband textures to accurately approximate noise with a desired spectrum. This allows us to achieve high-quality anisotropic filtering. Our approach is based solely on 2D textures, avoiding the memory overhead of techniques based on 3D noise tiles. We devise a technique to compensate for texture distortions to generate uniform noise on arbitrary meshes. We develop a GPU-based implementation of our technique that achieves similar rendering performance as state-of-the-art algorithms for procedural noise. In addition, it provides anisotropic filtering and achieves superior image quality.National Science Foundation (U.S.) (CAREER Award 0447561)Microsoft Research (New Faculty Fellowship)Alfred P. Sloan Foundation (Fellowship
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