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Item Liquid Penetration Modeling for Cloth Dyeing(The Eurographics Association, 2007) Morimoto, Yuki; Tsuruno, Reiji; Tomimatsu, Kiyoshi; Douglas W. Cunningham and Gary Meyer and Laszlo NeumannThis paper presents a model of cloth dyeing using the characteristics of the thread and weave pattern. The proposed dyeing model is based on Fick s second law that defines the molecular transfer under translational diffusion [Fic85]. The algorithm in the proposed model calculates the dyeing distribution from parameters such as the amount of dyeing, saturated amount, and pressure in each cell on a timeline. We improve the algorithm based on Fick s second law to consider a woven cloth structure and describe the proposed model of the structure of woven cloth as a two-layer cellular model. We then visualize the cloth using a simple 2D shading method of asperity by using the color distribution on a dyed image of real woven cloth. In addition, we provide a method for producing dyeing patterns without dyeing diffusion. The proposed method produces images that capture several of the characteristics of dyeing observed in real dyed cloth.Item Design of Multi-dimensional Transfer Functions Using Dimensional Reduction(The Eurographics Association, 2007) Pinto, Francisco de Moura; Freitas, Carla M. D. S.; K. Museth and T. Moeller and A. YnnermanDirect volume rendering techniques allow visualization of volume data without extracting intermediate geometry. The mapping from voxel attributes to optical properties is performed by transfer functions which, consequently, play a crucial role in building informative images from the data. One-dimensional transfer functions, which are based only on a scalar value per voxel, often do not provide proper visualizations. On the other hand, multidimensional transfer functions can perform more sophisticated data classification, based on vectorial voxel signatures. The transfer function design is a non-trivial and unintuitive task, especially in the multi-dimensional case. In this paper we propose a multi-dimensional transfer function design technique that uses self-organizing maps to perform dimensional reduction. Our approach gives uniform treatment to volume data containing voxel signatures of arbitrary dimension, and allows the use of any type of voxel attribute as part of the voxel signatures.Item Out of Core Photon-Mapping for Large Buildings(The Eurographics Association, 2005) Fradin, David; Meneveaux, Daniel; Horna, Sebastien; Kavita Bala and Philip DutreThis paper describes a new scheme for computing out-of-core global illumination in complex indoor scenes using a photon-mapping approach. Our method makes use of a cells-and-portals representation of the environment for preserving memory coherence and storing rays or photons. We have successfully applied our method to various buildings, composed of up to one billion triangles. As shown in the results, our method requires only a few hundred megabytes of memory for tracing more than 1.6 billion photons in large buildings.Item High-Quality Volume Rendering with Resampling in the Frequency Domain(The Eurographics Association, 2005) Artner, Martin; Möller, Torsten; Viola, Ivan; Gröller, Meister E.; Ken Brodlie and David Duke and Ken JoyThis work introduces a volume rendering technique that is conceptually based on the shear-warp factorization. We propose to perform the shear transformation in the frequency domain. Unlike the standard shear-warp algorithm, we allow for arbitrary sampling distances along the viewing rays, independent from the view direction. The accurate scaling of the volume slices is achieved by using the zero padding interpolation property. Finally, a high quality gradient estimation scheme is presented which uses the derivative theorem of the Fourier transform. Experimental results show that the presented method outperforms established algorithms in the quality of the produced images. If the data is sampled above the Nyquist rate the presented method is capable of a perfect reconstruction of the original function.Item General Linear Cameras with Finite Aperture(The Eurographics Association, 2007) Adams, Andrew; Levoy, Marc; Jan Kautz and Sumanta PattanaikA pinhole camera selects a two-dimensional set of rays from the four-dimensional light field. Pinhole cameras are a type of general linear camera, defined as planar 2D slices of the 4D light field. Cameras with finite apertures can be considered as the summation of a collection of pinhole cameras. In the limit they evaluate a two-dimensional integral of the four-dimensional light field. Hence a general linear camera with finite aperture factors the 4D light field into two integrated dimensions and two imaged dimensions. We present a simple framework for representing these slices and integral projections, based on certain eigenspaces in a two-plane parameterization of the light field. Our framework allows for easy analysis of focus and perspective, and it demonstrates their dual nature. Using our framework, we present analogous taxonomies of perspective and focus, placing within them the familiar perspective, orthographic, cross-slit, and bilinear cameras; astigmatic and anastigmatic focus; and several other varieties of perspective and focus.Item A study on textures and their perceptual visual dimensions as application for flexible and effective scientific visualization(The Eurographics Association, 2006) Taponecco, F.; S. Battiato and G. Gallo and F. StancoThe use of textures is fundamental in several areas of Computer Graphics, Computer Vision and Image Processing. In this work, we focus on their main relevant attributes, in order to define and design textures as effective visual representations for use in scientific visualization. We concentrate on the problem of visualizing complex multivariate and multi-dimensional datasets as well as in synthesizing multi-fields and temporal evolution of vectorial datasets visualization. Textures features, such as directionality, color and shape are particularly suited for use in a synthesis algorithm, and they serve as effective seed primitives, which can incorporate many visual dimensions for intuitive and flexible data mapping and encoding. As special application, we propose a level-based visualization approach, with a special focus on systematic layering of information for scientific datasets.Item Goblins by Spheroidal Weathering(The Eurographics Association, 2007) Beardall, Mathew; Farley, Mckay; Ouderkirk, Darius; Smith, Jeremy; Jones, Michael; Egbert, Parris; D. Ebert and S. MerillouHeight map models of terrain are computationally efficient but can not represent terrain with concave surfaces. We present an algorithm for generating sandstone goblins using a simulation of spheroidal weathering. Sandstone goblins are a kind of hoodoo which are characterized by rounded concave shapes. The weathering simulation uses bubbles centered on axis aligned voxels to approximate geometry-dependent effects of spheroidal weathering. We demonstrate that the algorithm, together with appropriate surface textures, produces visually plausible goblins at near interactive speeds for most simulation parameters.Item Sonar Explorer: A New Tool for Visualization of Fish Schools from 3D Sonar Data(The Eurographics Association, 2007) Balabanian, Jean-Paul; Viola, Ivan; Ona, Egil; Patel, Ruben; Groeller, Eduard; K. Museth and T. Moeller and A. YnnermanWe present a novel framework for analysis and visualization of fish schools in 3D sonar surveys. The 3D sonar technology is new and there have not been applications to visualize the data in 3D. We have created an application called Sonar Explorer that satisfies the requirements of domain scientists. Sonar Explorer provides easy and intuitive semi-automatic fish school tracking and survey map generation. The overall pipeline is described and all pipeline stages relevant for visualization are highlighted. We present techniques to deal with 3D sonar data specifics: highly anisotropic volume data aligned on a curvilinear grid. Domain scientists provide initial impressions on interaction and outlook.Item Pointillist and Glyph-based Visualization of Nanoparticles in Formation(The Eurographics Association, 2005) Saunders, P. Coleman; Interrante, Victoria; Garrick, Sean C.; Ken Brodlie and David Duke and Ken JoyIn this paper we offer new, texture-based methods for the visualization of multivariate data. These methods aim to more effectively convey the results of calculations simulating the formation of nanoparticles in turbulent fl ows. In these simulations, an entire distribution of nanoparticles is computed at every point across a two-dimensional slice of the data space, for every time step. Previous visualization methods have relied on multiple separate images to convey summary statistics about the datasets, including mean diameter and standard deviation of particle sizes. We introduce new methods based on texture which aim to enable the integrated understanding of the entire distribution of values at each point across the domain in terms of both summary statistics at each point and particle counts for various sizes of particles. Pointillism is used to represent the data at each point across the data range as a high-resolution texture. Circular glyphs can also be used to form a more discrete, spot-based texture, in which different characteristics of the distribution are encoded in various features of the spots.Item Perceptually Guided Rendering of Textured Point-based Models(The Eurographics Association, 2006) Qu, Lijun; Yuan, Xiaoru; Nguyen, Minh X.; Meyer, Gary W.; Chen, Baoquan; Windsheimer, Jered E.; Mario Botsch and Baoquan Chen and Mark Pauly and Matthias ZwickerIn this paper, we present a textured point-based rendering scheme that takes into account the masking properties of the human visual system. In our system high quality textures are mapped to point-based models. Given one texture, an importance map is first computed using the visual masking tool included in the JPEG2000 standard. This importance map indicates the masking potential of the texture. During runtime, point-based models are simplified and rendered based on this computed importance. In our point simplification method, called Simplification by Random Numbers (SRN), each point in the model is pre-assigned a random value. During rendering, the preassigned value is compared with the preferred local point density (derived from importance) to determine whether this point will be rendered. Our method can achieve coherent simplification for point models.