EG2016
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Item A Trip to Arts for Computer Graphics Students(The Eurographics Association, 2016) Svobodova, Lucie; Slavik, Pavel; Zara, Jiri; Beatriz Sousa Santos and Jean-Michel DischlerComplex and sophisticated projects, on which information technologists and artists meet and cooperate, often require an understanding of possible problems and solutions seen from both sides. While artists (creators) are usually somewhat familiar with current technologies, e.g. the Computer Graphics (CG) field, programmers are not well educated in the arts and their understanding of artistic needs is thus insufficient. In order to improve the education of CG students towards fine arts, we have created a BSc course on Art and Graphics design and have been running it for seven years. We consider this approach to education at a technologically oriented university as unusual and rare, but highly valuable for CG students. This paper describes the content of the course, summarizes the experience gained, and evaluates its usefulness for CG students in the subsequent MSc study program.Item Trajectory Data Visualization on Mobile Devices with Animated Maps(The Eurographics Association, 2016) Gonçalves, Tiago; Afonso, Ana Paula; Ferreira, António; Vieira, Ana Rita; T. Bashford-Rogers and L. P. SantosWith the increasing popularity of mobile devices (like smartphones and tablets) and georeferenced applications, more people record and analyse their own movement data. This pattern is noticeable with the increasing usage of mobile applications that, in addition to record the evolution of a person's location over time, also allow the visualization of that information, typically, in the form of 2D static maps, complemented with various representations to extract knowledge from the data. Despite the various studies addressing spatio-temporal data visualization, its application on mobile devices for the representation of personal trajectory data is still somewhat unexplored. Animated maps have been proposed as a potential intuitive and appealing technique for the visualization of information in a dynamic way, particularly for the detection of spatio-temporal data relations. We aim to address these issues by presenting a comparative study between static and animated representations of human movement on a mobile device context. Our results suggest that although it may not significantly improve user understanding of the data, the use of animated maps is a preferred and less interactively demanding option over static maps.Item Tiled Depth of Field Splatting(The Eurographics Association, 2016) Selgrad, Kai; Franke, Linus; Stamminger, Marc; Luis Gonzaga Magalhaes and Rafal MantiukWe present a method to compute post-processing depth of field (DOF) that produces more accurate results than previous approaches. Our method is based on existing approaches, namely DOF rendering by splatting and fast, tile-based particle accumulation. Using tile-based accumulation allows us to correctly sort out of focus pixels and apply proper alpha-blending to avoid artifacts commonly encountered with filter-based depth of field methods.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.Item Multi-Focus Plenoptic Simulator and Lens Pattern Mixing for Dense Depth Map Estimation(The Eurographics Association, 2016) Ferreira, Rodrigo; Cunha, Joel; Goncalves, Nuno; T. Bashford-Rogers and L. P. SantosLight field cameras capture a scene's multi-directional light field with one image, allowing the estimation of depth. In this paper, we introduce a fully automatic method for depth estimation from a single plenoptic image running a RANSAC-like algorithm for feature matching. The novelty about our method is the use of different focal-length lenses for multiple depth map refining, generating a dense depth map for future all-in-focus renders. We also present a plenoptic simulator which produces a plenoptic dataset from a 3D computer rendered scene. This simulator, which is unique, as far as we known, allows testing of plenoptic oriented algorithms since it can reproduce datasets with desired scene characteristics, providing the depth ground truth for error measurement. This work is a on-going project with promising results.Item Texel Shading(The Eurographics Association, 2016) Hillesland, Karl E.; Yang, J. C.; T. Bashford-Rogers and L. P. SantosWe have developed a texture space shading system built on modern graphics hardware. It begins with a conventional rasterization stage, but records texel accesses as shading work rather than running a shade per pixel. Shading is performed by a separate compute stage, storing the results in a texture. As a baseline, the texels correspond to those required for mipmapped texturing. A final stage collects data from the texture. Storing results in a texture allows for reuse across frames. We also show how adapting shade rate to less than once per pixel further increases performance. We vary shading load to show when these techniques provide a performance win, with up to 4.1x speedup in our experiments at shading times less than 4 ms.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 A Video Games Technologies Course: Teaching, Learning, and Research(The Eurographics Association, 2016) Amador, Gonçalo; Gomes, Abel; Beatriz Sousa Santos and Jean-Michel DischlerIn the last decade, several higher education institutions began to provide courses and/or degrees in games content creation, games design, and games development, largely because of the astonishing growth of games as one of the most powerful industries worldwide. This paper presents the course entitled “Video Games Technologies”, including its history, goals and methodology, as part of a MSc degree in Computer Science and Engineering. The focus is on the technologies, techniques, algorithms, data structures, and mathematics behind the design and development of game engines, instead of games themselves.Item Interactive Videos: Plausible Video Editing using Sparse Structure Points(The Eurographics Association and John Wiley & Sons Ltd., 2016) Chang, Chia-Sheng; Chu, Hung-Kuo; Mitra, Niloy J.; Joaquim Jorge and Ming LinVideo remains the method of choice for capturing temporal events. However, without access to the underlying 3D scene models, it remains difficult to make object level edits in a single video or across multiple videos. While it may be possible to explicitly reconstruct the 3D geometries to facilitate these edits, such a workflow is cumbersome, expensive, and tedious. In this work, we present a much simpler workflow to create plausible editing and mixing of raw video footage using only sparse structure points (SSP) directly recovered from the raw sequences. First, we utilize user-scribbles to structure the point representations obtained using structure-from-motion on the input videos. The resultant structure points, even when noisy and sparse, are then used to enable various video edits in 3D, including view perturbation, keyframe animation, object duplication and transfer across videos, etc. Specifically, we describe how to synthesize object images from new views adopting a novel image-based rendering technique using the SSPs as proxy for the missing 3D scene information. We propose a structure-preserving image warping on multiple input frames adaptively selected from object video, followed by a spatio-temporally coherent image stitching to compose the final object image. Simple planar shadows and depth maps are synthesized for objects to generate plausible video sequence mimicking real-world interactions. We demonstrate our system on a variety of input videos to produce complex edits, which are otherwise difficult to achieve.Item Agile Curriculum Design for the Creative Industries(The Eurographics Association, 2016) Palmer, Ian J.; Ralley, J.; Davenport, D.; Beatriz Sousa Santos and Jean-Michel DischlerThe creative industries thrive on novelty and technology, demanding professionals who can innovate, deliver to demanding briefs and constantly reinvent processes to match new problems. Traditional educational approaches can deliver some of these to a high level, but the demand for graduates who can thrive in these conditions is increasing. Escape Studios has reputation for rapidly upskilling graduates and making them ‘studio ready’ and is now moving to offer degree programmes including team working skills and commercial awareness impossible to include in its existing short intensive courses. This paper outlines the design process involved in creating these new programmes and provides case studies of some experiments in studio-based learning using industry briefs, peer and self-assessment and iterative working.Item Smooth Interpolation of Curve Networks with Surface Normals(The Eurographics Association, 2016) Stanko, Tibor; Hahmann, Stefanie; Bonneau, Georges-Pierre; Saguin-Sprynski, Nathalie; T. Bashford-Rogers and L. P. SantosRecent surface acquisition technologies based on microsensors produce three-space tangential curve data which can be transformed into a network of space curves with surface normals. This paper addresses the problem of surfacing an arbitrary closed 3D curve network with given surface normals. Thanks to the normal vector input, the patch finding problem can be solved unambiguously and an initial piecewise smooth triangle mesh is computed. The input normals are propagated throughout the mesh and used to compute mean curvature vectors. We then introduce a new variational optimization method in which the standard bi-Laplacian is penalized by a term based on the mean curvature vectors. The intuition behind this original approach is to guide the standard Laplacian-based variational methods by the curvature information extracted from the input normals. The normal input increases shape fidelity and allows to achieve globally smooth and visually pleasing shapes.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 Minimum Displacements For Cloth-obstacle Penetration Resolving(The Eurographics Association, 2016) Sun, Liming; Nyberg, Timo R.; Xiong, Gang; Ye, Juntao; T. Bashford-Rogers and L. P. SantosPre-existing penetrations often show up in many applications, particularly in garments fitting. The popular continuous collision detection (CCD) based methods are incapable of handling them, as there is no history information to rely on. On the other hand, surfaces of human bodies have normals defined to designate their orientation (i.e. front- and back-face), which are totally overlooked by CCD methods (thus they are orientation-free). In this paper we present a history-free method for separating two penetrating meshes, given that one of them represents a rigid object and has clarified surface orientation. This method computes all edge-face (E-F) intersections with discrete collision detection, and identifies illegal vertices with the help of surface orientation, and then builds a number of penetration stencils. On response, the stencil vertices are relocated into a penetrationfree state, via a global displacement minimizer. The proposed algorithm outperforms existing methods for handling solid/cloth collisions, thus is an effective tool for applications like virtual-try-on and example-based garment animation synthesis.Item Structure-adaptive Shape Editing for Man-made Objects(The Eurographics Association and John Wiley & Sons Ltd., 2016) Fu, Qiang; Chen, Xiaowu; Su, Xiaoyu; Li, Jia; Fu, Hongbo; Joaquim Jorge and Ming LinOne of the challenging problems for shape editing is to adapt shapes with diversified structures for various editing needs. In this paper we introduce a shape editing approach that automatically adapts the structure of a shape being edited with respect to user inputs. Given a category of shapes, our approach first classifies them into groups based on the constituent parts. The group-sensitive priors, including both inter-group and intra-group priors, are then learned through statistical structure analysis and multivariate regression. By using these priors, the inherent characteristics and typical variations of shape structures can be well captured. Based on such group-sensitive priors, we propose a framework for real-time shape editing, which adapts the structure of shape to continuous user editing operations. Experimental results show that the proposed approach is capable of both structure-preserving and structure-varying shape editing.Item Large Scale Terrain Generation from Tectonic Uplift and Fluvial Erosion(The Eurographics Association and John Wiley & Sons Ltd., 2016) Cordonnier, Guillaume; Braun, Jean; Cani, Marie-Paule; Benes, Bedrich; Galin, Éric; Peytavie, Adrien; Guérin, Éric; Joaquim Jorge and Ming LinAt large scale, landscapes result from the combination of two major processes: tectonics which generate the main relief through crust uplift, and weather which accounts for erosion. This paper presents the first method in computer graphics that combines uplift and hydraulic erosion to generate visually plausible terrains. Given a user-painted uplift map, we generate a stream graph over the entire domain embedding elevation information and stream flow. Our approach relies on the stream power equation introduced in geology for hydraulic erosion. By combining crust uplift and stream power erosion we generate large realistic terrains at a low computational cost. Finally, we convert this graph into a digital elevation model by blending landform feature kernels whose parameters are derived from the information in the graph. Our method gives high-level control over the large scale dendritic structures of the resulting river networks, watersheds, and mountains ridges.Item Deep Learning for Shape Analysis(The Eurographics Association, 2016) Bronstein, Michael; Kalogerakis, Evangelos; Rodola, Emanuele; Masci, Jonathan; Boscaini, Davide; Augusto Sousa and Kadi BouatouchThe past decade in computer vision research has witnessed the re-emergence of deep learning, and in particular convolutional neural network (CNN) techniques, allowing to learn powerful image feature representations from large collections of examples. Nevertheless, when attempting to apply standard deep learning methods to geometric data which by its nature is non-Euclidean (e.g. 3D shapes, graphs), one has to face fundamental differences between images and geometric objects. The purpose of this tutorial is to overview the foundations and the state of the art on learning techniques for 3D shape analysis. Special focus will be put on deep learning (CNN) applied to Euclidean and non-Euclidean manifolds for tasks of shape classification, retrieval and correspondence. The tutorial will present in a new light the problems of shape analysis, emphasizing the analogies and differences with the classical 2D setting and showing how to adapt popular learning schemes to deal with deformable shapes.Item Lowering the Entry Barrier for Students Programming Virtual Reality Applications(The Eurographics Association, 2016) Lambers, Martin; Beatriz Sousa Santos and Jean-Michel DischlerIn Computer Graphics, it is common practice to accompany lectures with hands-on tutorials and/or project assignments that allow students to write and run their own interactive graphics applications. In the special case of Virtual Reality courses, this approach is difficult to maintain since the software requirements pose a high entry barrier to students. In this paper, we propose a technique to significantly simplify Virtual Reality application programming, and implement it in an easy-to-use framework that supports the full range of typical Virtual Reality hardware setups, from head-mounted displays to multi-node, multi-GPU render clusters. The framework lowers the entry barrier for students and allows them to focus on course goals instead of fighting software complexities.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.