78 results
Search Results
Now showing 1 - 10 of 78
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 Predictive Modeling of Material Appearance: From the Drawing Board to Interdisciplinary Applications(The Eurographics Association, 2024) Baranoski, Gladimir V. G.; Mania, Katerina; Artusi, AlessandroThis tutorial addresses one of the fundamental and timely topics of computer graphics research, namely the predictive modeling of material appearance. Although this topic is deeply rooted in traditional areas like rendering and natural phenomena simulation, this tutorial is not limited to cover contents connected to these areas. It also closely looks into the scientific methodology employed in the development of predictive models of light and matter interactions. Given the widespread use of this methodology to find modeling solutions for problems within and outside computer graphics, its discussion from a ''behind the scenes'' perspective aims to underscore practical and far-reaching aspects of interdisciplinary research that are often overlooked in related publications. More specifically, this tutorial unveils constraints and pitfalls found in each of the key stages of the model development process, namely data collection, design and evaluation, and brings forward alternatives to tackle them effectively. Furthermore, besides being a central component of realistic image synthesis frameworks, predictive material appearance models have a scope of applications that can be extended far beyond the generation of believable images. For instance, they can be employed to accelerate the hypothesis generation and validation cycles of research across a wide range of fields, from biology and medicine to photonics and remote sensing, among others. These models can also be used to generate comprehensive in silico (computational) datasets to support the translation of knowledge advances in those fields to real-world applications (e.g., the noninvasive screening of medical conditions and the remote detection of environmental hazards). In fact, a number of them are already being used in physical and life sciences, notably to support investigations seeking to strengthen the current understanding about material appearance changes prompted by mechanisms which cannot be fully studied using standard ''wet'' experimental procedures. Accordingly, such interdisciplinary research initiatives are also discussed in this tutorial through selected case studies involving the use of predictive material appearance models to elucidate challenging scientific questions.Item A Virtual and Augmented Reality Course Based on Inexpensive Interaction Devices and Displays(The Eurographics Association, 2015) Santos, Beatriz Sousa; Dias, Paulo; Madeira, Joaquim; M. Bronstein and M. TeschnerIn the last years a plethora of affordable displays, sensors, and interaction devices has reached the market, fostering the application of Virtual and Augmented Reality to many new situations. Yet, creating such applications requires a good understanding of the field and specific technical skills typically not provided by current Computer Science and Engineering education. This paper presents a graduate level course offered to MSc. Programs in Computer and Electrical Engineering which introduces the main concepts, techniques and tools in Virtual and Augmented Reality. The aim is to provide students with enough background to understand, design, implement and test such applications. The course organization, the main issues addressed and bibliography, the sensors, interaction devices and displays used, and a sample of the practical projects are briefly described. Major issues are discussed and conclusions are drawn.Item Compressed Multiresolution Hierarchies for High-Quality Precomputed Shadows(The Eurographics Association and John Wiley & Sons Ltd., 2016) Scandolo, Leonardo; Bauszat, Pablo; Eisemann, Elmar; Joaquim Jorge and Ming LinThe quality of shadow mapping is traditionally limited by texture resolution. We present a novel lossless compression scheme for high-resolution shadow maps based on precomputed multiresolution hierarchies. Traditional multiresolution trees can compactly represent homogeneous regions of shadow maps at coarser levels, but require many nodes for fine details. By conservatively adapting the depth map, we can significantly reduce the tree complexity. Our proposed method offers high compression rates, avoids quantization errors, exploits coherency along all data dimensions, and is well-suited for GPU architectures. Our approach can be applied for coherent shadow maps as well, enabling several applications, including high-quality soft shadows and dynamic lights moving on fixed-trajectories.Item Peripheral Retinal Image Simulation Based on Retina Shapes(The Eurographics Association, 2016) Dias, Catarina; Wick, Michael; Rifai, Katharina; Wahl, Siegfried; T. Bashford-Rogers and L. P. SantosWe present a method to render the image of a scene reaching the retina, the retinal image, taking into account human offaxis optical aberrations. To this end, we consider realistic wide-angle eye models that offer an anatomical description of the refractive structures of the eye as a set of lenses and accurately reproduce the optical aberrations in the periphery. We then combine these with representative retinal shapes and with distributed ray tracing. Due to the interplay between the eye model and the curved retina, we obtain a realistic simulation of the retinal image, not only foveally but also in the periphery.Item Implicit Formulation for SPH-based Viscous Fluids(The Eurographics Association and John Wiley & Sons Ltd., 2015) Takahashi, Tetsuya; Dobashi, Yoshinori; Fujishiro, Issei; Nishita, Tomoyuki; Lin, Ming C.; Olga Sorkine-Hornung and Michael WimmerWe propose a stable and efficient particle-based method for simulating highly viscous fluids that can generate coiling and buckling phenomena and handle variable viscosity. In contrast to previous methods that use explicit integration, our method uses an implicit formulation to improve the robustness of viscosity integration, therefore enabling use of larger time steps and higher viscosities. We use Smoothed Particle Hydrodynamics to solve the full form of viscosity, constructing a sparse linear system with a symmetric positive definite matrix, while exploiting the variational principle that automatically enforces the boundary condition on free surfaces. We also propose a new method for extracting coefficients of the matrix contributed by second-ring neighbor particles to efficiently solve the linear system using a conjugate gradient solver. Several examples demonstrate the robustness and efficiency of our implicit formulation over previous methods and illustrate the versatility of our method.Item Eye-tracktive: Measuring Attention to Body Parts when Judging Human Motions(The Eurographics Association, 2015) Ennis, Cathy; Hoyet, Ludovic; O'Sullivan, Carol; B. Bickel and T. RitschelVirtual humans are often endowed with human-like characteristics to make them more appealing and engaging. Motion capture is a reliable way to represent natural motion on such characters, thereby allowing a wide range of animations to be automatically created and replicated. However, interpersonal differences in actors' performances can be subtle and complex, yet have a strong effect on the human observer. Such effects can be very difficult to express quantitatively or indeed even qualitatively. We investigate two subjective human motion characteristics: attractiveness and distinctiveness. We conduct a perceptual experiment, where participants' eye movements are tracked while they rate the motions of a range of actors. We found that participants fixate mostly on the torso, regardless of gait and actor sex, and very little on the limbs. However, they self-reported that they used hands, elbows and feet in their judgments, indicating a holistic approach to the problem.Item Variable k-buffer using Importance Maps(The Eurographics Association, 2017) Vasilakis, Andreas-Alexandros; Vardis, Konstantinos; Papaioannou, Georgios; Moustakas, Konstantinos; Adrien Peytavie and Carles BoschSuccessfully predicting visual attention can significantly improve many aspects of computer graphics and games. Despite the thorough investigation in this area, selective rendering has not addressed so far fragment visibility determination problems. To this end, we present the first ''selective multi-fragment rendering'' solution that alters the classic k-buffer construction procedure from a fixed-k to a variable-k per-pixel fragment allocation guided by an importance-driven model. Given a fixed memory budget, the idea is to allocate more fragment layers in parts of the image that need them most or contribute more significantly to the visual result. An importance map, dynamically estimated per frame based on several criteria, is used for the distribution of the fragment layers across the image. We illustrate the effectiveness and quality superiority of our approach in comparison to previous methods when performing order-independent transparency rendering in various, high depth-complexity, scenarios.Item Skeleton-based Joints Position Detection(The Eurographics Association, 2014) Madaras, Martin; Piovarci, Michal; Kovacovský, Tomás; Mathias Paulin and Carsten DachsbacherWe present a system for detection of joint positions in scans of articulated models. Our method is based purely on skeletons extracted from scanned point clouds of input models. First, skeletons are extracted from scans and then an estimation of possible matches between skeletons is performed. The matches are evaluated and sorted out. The whole matching process is fully automatic, but some user-driven suggestions can be included. Finally, we pick the best matching of skeletons and create a union-skeleton containing all the nodes from all the skeletons. We find nodes in the union-skeleton with rotation changes higher than the predefined threshold. We take these nodes as joints and visualize them in original scans.Item Improving Sampling-based Motion Control(The Eurographics Association and John Wiley & Sons Ltd., 2015) Liu, Libin; Yin, KangKang; Guo, Baining; Olga Sorkine-Hornung and Michael WimmerWe address several limitations of the sampling-based motion control method of Liu et at. [LYvdP 10]. The key insight is to learn from the past control reconstruction trials through sample distribution adaptation. Coupled with a sliding window scheme for better performance and an averaging method for noise reduction, the improved algorithm can efficiently construct open-loop controls for long and challenging reference motions in good quality. Our ideas are intuitive and the implementations are simple. We compare the improved algorithm with the original algorithm both qualitatively and quantitatively, and demonstrate the effectiveness of the improved algorithm with a variety of motions ranging from stylized walking and dancing to gymnastic and Martial Arts routines.