24 results
Search Results
Now showing 1 - 10 of 24
Item Geometry and Attribute Compression for Voxel Scenes(The Eurographics Association and John Wiley & Sons Ltd., 2016) Dado, Bas; Kol, Timothy R.; Bauszat, Pablo; Thiery, Jean-Marc; Eisemann, Elmar; Joaquim Jorge and Ming LinVoxel-based approaches are today's standard to encode volume data. Recently, directed acyclic graphs (DAGs) were successfully used for compressing sparse voxel scenes as well, but they are restricted to a single bit of (geometry) information per voxel. We present a method to compress arbitrary data, such as colors, normals, or reflectance information. By decoupling geometry and voxel data via a novel mapping scheme, we are able to apply the DAG principle to encode the topology, while using a palette-based compression for the voxel attributes, leading to a drastic memory reduction. Our method outperforms existing state-of-the-art techniques and is well-suited for GPU architectures. We achieve real-time performance on commodity hardware for colored scenes with up to 17 hierarchical levels (a 128K3 voxel resolution), which are stored fully in core.Item Inertial Steady 2D Vector Field Topology(The Eurographics Association and John Wiley & Sons Ltd., 2016) Günther, Tobias; Theisel, Holger; Joaquim Jorge and Ming LinVector field topology is a powerful and matured tool for the study of the asymptotic behavior of tracer particles in steady flows. Yet, it does not capture the behavior of finite-sized particles, because they develop inertia and do not move tangential to the flow. In this paper, we use the fact that the trajectories of inertial particles can be described as tangent curves of a higher dimensional vector field. Using this, we conduct a full classification of the first-order critical points of this higher dimensional flow, and devise a method to their efficient extraction. Further, we interactively visualize the asymptotic behavior of finite-sized particles by a glyph visualization that encodes the outcome of any initial condition of the governing ODE, i.e., for a varying initial position and/or initial velocity. With this, we present a first approach to extend traditional vector field topology to the inertial case.Item Generalized Diffusion Curves: An Improved Vector Representation for Smooth-Shaded Images(The Eurographics Association and John Wiley & Sons Ltd., 2016) Jeschke, Stefan; Joaquim Jorge and Ming LinThis paper generalizes the well-known Diffusion Curves Images (DCI), which are composed of a set of Bezier curves with colors specified on either side. These colors are diffused as Laplace functions over the image domain, which results in smooth color gradients interrupted by the Bezier curves. Our new formulation allows for more color control away from the boundary, providing a similar expressive power as recent Bilaplace image models without introducing associated issues and computational costs. The new model is based on a special Laplace function blending and a new edge blur formulation. We demonstrate that given some user-defined boundary curves over an input raster image, fitting colors and edge blur from the image to the new model and subsequent editing and animation is equally convenient as with DCIs. Numerous examples and comparisons to DCIs are presented.Item Regularizing Image Reconstruction for Gradient-Domain Rendering with Feature Patches(The Eurographics Association and John Wiley & Sons Ltd., 2016) Manzi, Marco; Vicini, Delio; Zwicker, Matthias; Joaquim Jorge and Ming LinWe present a novel algorithm to reconstruct high-quality images from sampled pixels and gradients in gradient-domain rendering. Our approach extends screened Poisson reconstruction by adding additional regularization constraints. Our key idea is to exploit local patches in feature images, which contain per-pixels normals, textures, position, etc., to formulate these constraints. We describe a GPU implementation of our approach that runs on the order of seconds on megapixel images. We demonstrate a significant improvement in image quality over screened Poisson reconstruction under the L1 norm. Because we adapt the regularization constraints to the noise level in the input, our algorithm is consistent and converges to the ground truth.Item Transferring and Animating a non T-pose Model to a T-pose Model(The Eurographics Association, 2016) Hajari, Nasim; Cheng, Irene; Basu, Anup; Luis Gonzaga Magalhaes and Rafal MantiukNon T-pose animation is a technique that attempts to generate natural transformations between any non T-pose skeletons to the neutral T-pose skeleton. It is not always easy to extract or embed a T-pose animation skeleton into a 3D human model in an arbitrary initial position. This is even more problematic for natural human models obtained by 3D scanning, especially models of babies and kids. In addition, transforming a non T-pose to a T-pose requires a large amount of calculations. Hence, many commercially available software do not provide efficient methods to standardize non T-pose skeletons. This paper focuses on developing a simplified transformation method, which enables skeletons in arbitrary poses to be standardized and used in other media conveniently.Item Single Image Weathering via Exemplar Propagation(The Eurographics Association and John Wiley & Sons Ltd., 2016) Iizuka, Satoshi; Endo, Yuki; Kanamori, Yoshihiro; Mitani, Jun; Joaquim Jorge and Ming LinThis paper presents an efficient approach for generating weathering effects with detailed appearance variations in a single image. Previous approaches merely change chroma or reflectance of weathered objects, which is not sufficient for materials with detailed shading and texture variations, such as growing moss and peeling plaster. Our method propagates such detailed features via seamless patch-based synthesis driven by weathering degree distribution. Unlike previous methods, the weathering degrees are calculated efficiently using Radial Basis Functions even for materials with wide color variations. We use graph cut-based optimization to identify the most weathered region as a ''weathering exemplar'', from which we sample weathering patches. We demonstrate our method enables us to generate various types of detailed weathering effects interactively.Item Near-Instant Capture of High-Resolution Facial Geometry and Reflectance(The Eurographics Association and John Wiley & Sons Ltd., 2016) Fyffe, Graham; Graham, Paul; Tunwattanapong, Borom; Ghosh, Abhijeet; Debevec, Paul; Joaquim Jorge and Ming LinWe present a near-instant method for acquiring facial geometry and reflectance using a set of commodity DSLR cameras and flashes. Our setup consists of twenty-four cameras and six flashes which are fired in rapid succession with subsets of the cameras. Each camera records only a single photograph and the total capture time is less than the 67ms blink reflex. The cameras and flashes are specially arranged to produce an even distribution of specular highlights on the face. We employ this set of acquired images to estimate diffuse color, specular intensity, specular exponent, and surface orientation at each point on the face. We further refine the facial base geometry obtained from multi-view stereo using estimated diffuse and specular photometric information. This allows final submillimeter surface mesostructure detail to be obtained via shape-from-specularity. The final system uses commodity components and produces models suitable for authoring high-quality digital human characters.Item Physically-based Rendering of Highly Scattering Fluorescent Solutions using Path Tracing(The Eurographics Association, 2016) Abdellah, Marwan; Bilgili, Ahmet; Eilemann, Stefan; Markram, Henry; Schürmann, Felix; Luis Gonzaga Magalhaes and Rafal MantiukWe introduce a physically-plausible Monte Carlo rendering technique that is capable of treating highly scattering participating media in the presence of fluorescent mixtures. Our model accounts for the actual intrinsic spectroscopic characteristics of fluorescent dyes. The model leads to an estimator for simulating the light interaction with highly scattering fluorescent-tagged participating media. Our system is applied to render images of two fluorescent solutions under different conditions. The model is qualitatively analyzed and validated against experimental emission spectra of fluorescent dyes.Item Interactive Monte-Carlo Ray-Tracing Upsampling(The Eurographics Association, 2016) Boughida, Malik; Groueix, Thibault; Boubekeur, Tamy; Luis Gonzaga Magalhaes and Rafal MantiukWe propose a practical method to approximate global illumination at interactive framerates for dynamic scenes. We address multi-bounce, visibility-aware indirect lighting, for diffuse to moderately glossy materials, relying on GPU-accelerated raytracing for this purpose. While Monte-Carlo ray-tracing algorithms offer unbiased results, they produce images which are, under interactive constraints, extremely noisy, even with GPU acceleration. Unfortunately, filtering them to reach visual appeal induces a large kernel, which is not compatible with interactive framerate. We address this problem using a simple downsampling approach. First, we trace indirect paths on a uniformly distributed subset of pixels, decorrelating diffuse and specular components of lighting. Then, we perform a joint bilateral upsampling on both components, taking inspiration from deferred shading by driving this upsampling with a full-resolution G-Buffer. Our solution provides smooth results, does not require any pre-computations, and is both easy to implement and flexible, as it can be used with any generation strategy for indirect rays.Item Buoyancy Optimization for Computational Fabrication(The Eurographics Association and John Wiley & Sons Ltd., 2016) Wang, Lingfeng; Whiting, Emily; Joaquim Jorge and Ming LinThis paper introduces a design and fabrication pipeline for creating floating forms. Our method optimizes for buoyant equilibrium and stability of complex 3D shapes, applying a voxel-carving technique to control the mass distribution. The resulting objects achieve a desired floating pose defined by a user-specified waterline height and orientation. In order to enlarge the feasible design space, we explore novel ways to load the interior of a design using prefabricated components and casting techniques. 3D printing is employed for high-precision fabrication. For larger scale designs we introduce a method for stacking lasercut planar pieces to create 3D objects in a quick and economic manner. We demonstrate fabricated designs of complex shape in a variety of floating poses.