EG2013
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Item A Segmentation Transfer Method for Articulated Models(The Eurographics Association, 2013) Elghoul, Esma; Verroust-Blondet, Anne; M.- A. Otaduy and O. SorkineIn this paper, we propose using a pre-segmented example model to perform semantic-oriented segmentation of non-rigid 3D models of the same class (human, octopus, quadrupeds, etc.). Using the fact that the same type of non-rigid models share the same global topological structure, we exploit coarse topological shape attributes in conjunction with a seed-based segmentation approach to transfer a meaningful and consistent segmentation from the example to the target models. Promising results of inter-shape segmentation transfer are shown and discussed for different classes of models.Item Real-Time Image-Based Volume Lighting(The Eurographics Association, 2013) Delalandre, Cyril; Gautron, Pascal; Marvie, Jean-Eudes; M.- A. Otaduy and O. SorkineThe interaction of translucent objects with light creates complex effects such as scattering, absorption and volumetric shadows. While most accurate rendering approaches resort to heavy computations, recent needs in interactive applications have led to new types of algorithms, trading quality or genericity for speed.Item Transfinite Surface Patches Using Curved Ribbons(The Eurographics Association, 2013) Várady, Tamás; Salvi, Péter; Rockwood, Alyn; M.- A. Otaduy and O. SorkineAn important problem in Computer Aided Design is to create digital representations for complex free-form objects that produce nice, predictable shapes and facilitate real-time editing in 3D. The clue to curve network-based design is the construction of smoothly connected multi-sided patches. A new type of transfinite surface, called Composite Ribbon (CR) patch is introduced, that is a combination of curved ribbons and ensures G1 continuity over non-regular, convex polygonal domains. After discussing the construction and the preferred parameterization scheme, a few simple examples conclude the paper.Item Coupled Quasi-harmonic Bases(The Eurographics Association and Blackwell Publishing Ltd., 2013) Kovnatsky, Artiom; Bronstein, Michael M.; Bronstein, Alexander M.; Glashoff, Klaus; Kimmel, Ron; I. Navazo, P. PoulinThe use of Laplacian eigenbases has been shown to be fruitful in many computer graphics applications. Today, state-of-the-art approaches to shape analysis, synthesis, and correspondence rely on these natural harmonic bases that allow using classical tools from harmonic analysis on manifolds. However, many applications involving multiple shapes are obstacled by the fact that Laplacian eigenbases computed independently on different shapes are often incompatible with each other. In this paper, we propose the construction of common approximate eigenbases for multiple shapes using approximate joint diagonalization algorithms, taking as input a set of corresponding functions (e.g. indicator functions of stable regions) on the two shapes. We illustrate the benefits of the proposed approach on tasks from shape editing, pose transfer, correspondence, and similarity.Item State of the Art of Parallel Coordinates(The Eurographics Association, 2013) Heinrich, Julian; Weiskopf, Daniel; M. Sbert and L. Szirmay-KalosThis work presents a survey of the current state of the art of visualization techniques for parallel coordinates. It covers geometric models for constructing parallel coordinates and reviews methods for creating and understanding visual representations of parallel coordinates. The classification of these methods is based on a taxonomy that was established from the literature and is aimed at guiding researchers to find existing techniques and identifying white spots that require further research. The techniques covered in this survey are further related to an established taxonomy of knowledge-discovery tasks to support users of parallel coordinates in choosing a technique for their problem at hand. Finally, we discuss the challenges in constructing and understanding parallel-coordinates plots and provide some examples from different application domains.Item Stochastic Depth Buffer Compression using Generalized Plane Encoding(The Eurographics Association and Blackwell Publishing Ltd., 2013) Andersson, Magnus; Munkberg, Jacob; Akenine-Möller, Tomas; I. Navazo, P. PoulinIn this paper, we derive compact representations of the depth function for a triangle undergoing motion or defocus blur. Unlike a static primitive, where the depth function is planar, the depth function is a rational function in time and the lens parameters. Furthermore, we show how these compact depth functions can be used to design an efficient depth buffer compressor/decompressor, which significantly lowers total depth buffer bandwidth usage for a range of test scenes. In addition, our compressor/decompressor is simpler in the number of operations needed to execute, which makes our algorithm more amenable for hardware implementation than previous methodsItem Graph Abstraction for Simplified Proofreading of Slice-based Volume Segmentation(The Eurographics Association, 2013) Sicat, Ronell B.; Hadwiger, Markus; Mitra, Niloy J.; M.- A. Otaduy and O. SorkineVolume segmentation is an integral data analysis tool in experimental science. For example, in neuroscience, analysis of 3D volumes of neural structures from electron microscopy data is a key analysis step. Despite advances in computational methods, experts still prefer to manually proofread and correct the automatic segmentation outputs. Such corrections are often annotated at the level of data slices in order to minimize distortion artifacts and effectively handle the massive data volumes. In absence of crucial global context in 3D, such a workflow remains tedious, time consuming, and error prone. In this paper, we present a simple graph-based abstraction for segmentation volumes leading to an interactive proofreading tool making the process simpler, faster, and intuitive. Starting from an initial volume segmentation, we first construct a graph abstraction and then use it to identify potential problematic regions for the user to investigate and correct spurious segmentations, if identified. We also use the graph to suggest automatic corrections, thus drastically simplifying the proofreading effort. We implemented the proofreading tool as an Avizo c plugin and evaluated the method on complex real-world use cases.Item Video Visualization(The Eurographics Association, 2013) Borgo, Rita; Chen, Min; Höferlin, Markus; Kurzhals, Kuno; Legg, Phil; Walton, Simon; Weiskopf, Daniel; Diego Gutierrez and Karol MyszkowskiVideo data, generated by the entertainment industry, security and traffic cameras, video conferencing systems, video emails, and so on, is particularly time-consuming to process by human beings. The field of visualization has provided this challenging problem with a collection of techniques that transform videos to different visual forms in order to reduce the time required to watch the video. In this tutorial, we will introduce the concept of video visualization, and several elementary techniques for processing and rendering a video into a compact visual representation. We will describe a family of visual representations, a set of insight obtained from empirical studies, and a collection of applications.Item Poisson Image Analogy: Texture-Aware Seamless Cloning(The Eurographics Association, 2013) Yoshizawa, Shin; Yokota, Hideo; Miguel Chover and A. Augusto de SousaSynthesizing two images with seamless boundaries, i.e. seamless image cloning, is important and has many useful applications in CG. Previous approaches do not produce realistic results if texture details of the two images are different.We propose a novel texture-aware seamless cloning framework based on separately processing the details and base image colors. The proposed framework provides realistic cloning results with seamless texture details.Item Multi-Camera Acquisition and Placement Strategy for Displaying High-Resolution Images for Telepresence Systems(The Eurographics Association, 2013) Islam, Tariqul; Ohl, Stephan; Staadt, Oliver; Miguel Chover and A. Augusto de SousaLife-size high-resolution telepresence systems, used for remote collaboration, face the problem of transmitting huge data from multiple viewpoints. We present different strategies focusing on efficient camera selection and acquisition method to discard part of image data for transmission as a preprocess to classical video compression schemes. At the the receiver site, part of the omitted data can be restored by means of super-resolution methods.Item Mutable Elastic Models for Sculpting Structured Shapes(The Eurographics Association and Blackwell Publishing Ltd., 2013) Milliez, Antoine; Wand, Michael; Cani, Marie-Paule; Seidel, Hans-Peter; I. Navazo, P. PoulinIn this paper, we propose a new paradigm for free-form shape deformation. Standard deformable models minimize an energy measuring the distance to a single target shape. We propose a new, ''mutable'' elastic model. It represents complex geometry by a collection of parts and measures the distance of each part measures to a larger set of alternative rest configurations. By detecting and reacting to local switches between best-matching rest states, we build a 3D sculpting system: It takes a structured shape consisting of parts and replacement rules as input. The shape can subsequently be elongated, compressed, bent, cut, and merged within a constraints-based free-form editing interface, where alternative rest-states model to such changes. In practical experiments, we show that the approach yields a surprisingly intuitive and easy to implement interface for interactively designing objects described by such discrete shape grammars, for which direct shape control mechanisms were typically lacking.Item Material Editing in Complex Scenes by Surface Light Field Manipulation and Reflectance Optimization(The Eurographics Association and Blackwell Publishing Ltd., 2013) Nguyen, Chuong H.; Scherzer, Daniel; Ritschel, Tobias; Seidel, Hans-Peter; I. Navazo, P. PoulinThis work addresses the challenge of intuitive appearance editing in scenes with complex geometric layout and complex, spatially-varying indirect lighting. In contrast to previous work, that aimed to edit surface reflectance, our system allows a user to freely manipulate the surface light field. It then finds the best surface reflectance that ''explains'' the surface light field manipulation. Instead of classic L2 fitting of reflectance to a combination of incoming and exitant illumination, our system infers a sparse L0 change of shading parameters instead. Consequently, our system does not require ''diffuse'' or ''glossiness'' brushes or any such understanding of the underlying reflectance parametrization. Instead, it infers reflectance changes from scribbles made by a single simple color brush tool alone: Drawing a highlight will increase Phong specular; blurring a mirror reflection will decrease glossiness; etc. A sparse-solver framework operating on a novel point-based, pre-convolved lighting representation in combination with screen-space edit upsampling allows to perform editing interactively on a GPU.Item Seam-Driven Image Stitching(The Eurographics Association, 2013) Gao, Junhong; Li, Yu; Chin, Tat-Jun; Brown, Michael S.; M.- A. Otaduy and O. SorkineImage stitching computes geometric transforms to align images based on the best fit of feature correspondences between overlapping images. Seam-cutting is used afterwards to to hide misalignment artifacts. Interestingly it is often the seam-cutting step that is the most crucial for obtaining a perceptually seamless result. This motivates us to propose a seam-driven image stitching strategy where instead of estimating a geometric transform based on the best fit of feature correspondences, we evaluate the goodness of a transform based on the resulting visual quality of the seam-cut. We show that this new image stitching strategy can often produce better perceptual results than existing methods especially for challenging scenes.Item Primitive Trees for Precomputed Distance Queries(The Eurographics Association and Blackwell Publishing Ltd., 2013) Lee, Sung-Ho; Park, Taejung; Kim, Chang-Hun; I. Navazo, P. PoulinWe propose the primitive tree, a novel and compact space-partition method that samples and reconstructs a distance field with high accuracy, even for regions far from the surfaces. The primitive tree is based on the octree and stores the indices of the nearest primitives in its leaf nodes. Most previous approaches have involved a trade-off between accuracy and speed in distance queries, but our method can improve both aspects simultaneously. In addition, our method can sample unsigned distance fields effectively, even for self-intersecting and nonmanifold models. We present test results showing that our method can sample and represent large scenes, with more than ten million triangles, rapidly and accurately.Item DCGI Laboratories at CTU Prague, Czech Republic(The Eurographics Association, 2013) Bittner, Jiri; Zara, Jiri; J. C. Torres and A. LecuyerThe Department of Computer Graphics and Interaction (DCGI) covers education and research activities in Computer Graphics and Human-Computer Interaction areas at the Czech Technical University in Prague (CTU). This paper presents the staff, laboratories, projects, and selected scientific achievements of the DCGI.Item Computational Displays: Combining Optical Fabrication, Computational Processing, and Perceptual Tricks to Build the Displays of the Future(The Eurographics Association, 2013) Wetzstein, Gordon; Lanman, Douglas; Didyk, Piotr; Diego Gutierrez and Karol MyszkowskiWith the invention of integral imaging and parallax barriers in the beginning of the 20th century, glasses-free 3D displays have become feasible. Only today -more than a century later- glasses-free 3D displays are finally emerging in the consumer market. The technologies being employed in current-generation devices, however, are fundamentally the same as what was invented 100 years ago. With rapid advances in optical fabrication, digital processing power, and computational models for human perception, a new generation of display technology is emerging: computational displays exploring the co-design of optical elements and computational processingwhile taking particular characteristics of the human visual system into account. This technology does not only encompass 3D displays, but also next-generation projection systems, high dynamic range displays, perceptually-driven devices, and computational probes. This tutorial serves as an introduction to the emerging field of computational displays. The pedagogical goal of this tutorial is to provide the audience with the tools necessary to expand their research endeavorsby providing step-by-step instructions on all aspects of computational displays: display optics, mathematical analysis, efficient computational processing, computational perception, and, most importantly, the effective combination of all these aspects. Specifically, we will discuss a wide variety of different applications and hardware setups of computational displays, including high dynamic range displays, advanced projection systems as well as glasses-free 3D display. The latter example, computational light field displays, will be discussed in detail. In the tutorial presentation, supplementary notes, and an accompanying website, we will provide source code that drives various display incarnations at real-time framerates, detailed instructions on how to fabricate novel displays from off-the-shelf components, and intuitive mathematical analyses that will make it easy for researchers with various backgrounds to get started in the emerging field of computational displays. We believe that computational display technology is one of the hottest" topics in the graphics community today; with this tutorial we will make it accessible for a diverse audience. This tutorial was previously taught as a course at SIGGRAPH 2012.We will discuss all aspects of computational displays in detail. Specifically,we begin by introducing the concept and discussing a variety of example displays that exploit the joint-design of optical components and computational processing for applications such as high dynamic range image and wide color gamut display, extended depth of field projection, and high-dimensional information display for computer vision applications. We will then proceed to discussing state-of-the-art computational light field displays in detail. In particular, we will focus on how high-speed displays, multiple stacked LCDs, and directional backlighting combined with advanced mathematical analysis and efficient computational processing provide the foundations of 3D displays of the future. Finally, we will review psycho-physiological aspects that are of importance for display design and demonstrate how perceptually-driven computational displays can enhance the capability of current technology.Item Computational Fabrication and Display of Material Appearance(The Eurographics Association, 2013) Hullin, Matthias B.; Ihrke, Ivo; Heidrich, Wolfgang; Weyrich, Tim; Damberg, Gerwin; Fuchs, Martin; M. Sbert and L. Szirmay-KalosAfter decades of research on digital representations of material and object appearance, computer graphics has more recently turned to the problem of creating physical artifacts with controllable appearance characteristics. While this work has mostly progressed in two parallel streams - display technologies as well as novel fabrication processes - we believe there is a large overlap and the potential for synergies between these two approaches. In this report, we summarize research efforts from the worlds of fabrication display, and categorize the different approaches into a common taxonomy. We believe that this report can serve as a basis for systematic exploration of the design space in future research.Item Computing and Fabricating Multiplanar Models(The Eurographics Association and Blackwell Publishing Ltd., 2013) Chen, Desai; Sitthi-amorn, Pitchaya; Lan, Justin T.; Matusik, Wojciech; I. Navazo, P. PoulinWe present a method for converting computer 3D models into physical equivalents. More specifically, we address the problem of approximating a 3D textured mesh using a small number of planar polygonal primitives that form a closed surface. This simplified representation allows us to easily manufacture individual components using computer controlled cutters (e.g., laser cutters or CNC machines). These polygonal pieces can be assembled into the final 3D model using internal planar connectors that are manufactured simultaneously. Our shape approximation algorithm iteratively assigns mesh faces to planar segments and slowly deforms these faces towards corresponding segments. This approach ensures that the output for a given closed mesh is still a closed mesh and avoids introducing self-intersections. After this step we also compute the shape of polygonal connectors that internally hold the whole mesh surface. Both the polygonal surface elements and connectors can be manufactured in a single cutting pass. We validate the use of our method by computing and manufacturing a variety of textured polyhedral models.Item Example-based Interpolation and Synthesis of Bidirectional Texture Functions(The Eurographics Association and Blackwell Publishing Ltd., 2013) Ruiters, Roland; Schwartz, Christopher; Klein, Reinhard; I. Navazo, P. PoulinBidirectional Texture Functions (BTF) have proven to be a well-suited representation for the reproduction of measured real-world surface appearance and provide a high degree of realism. We present an approach for designing novel materials by interpolating between several measured BTFs. For this purpose, we transfer concepts from existing texture interpolation methods to the much more complex case of material interpolation. We employ a separation of the BTF into a heightmap and a parallax compensated BTF to cope with problems induced by parallax, masking and shadowing within the material. By working only on the factorized representation of the parallax compensated BTF and the heightmap, it is possible to efficiently perform the material interpolation. By this novel method to mix existing BTFs, we are able to design plausible and realistic intermediate materials for a large range of different opaque material classes. Furthermore, it allows for the synthesis of tileable and seamless BTFs and finally even the generation of gradually changing materials following user specified material distribution maps.Item Perceptually Motivated Real-Time Compression of Motion Data Enhanced by Incremental Encoding and Parameter Tuning(The Eurographics Association, 2013) Firouzmanesh, Amirhossein; Cheng, Irene; Basu, Anup; M.- A. Otaduy and O. SorkineWe address the problem of efficient real-time motion data compression considering human perception. Using incremental encoding plus a database of motion primitives for each key point, our method achieves a higher or competitive compression rate with less online overhead. Trade-off between visual quality and bandwidth usage can be tuned by varying a single threshold value. A user study was performed to measure the sensitivity of human subjects to reconstruction errors in key rotation angles. Based on these evaluations we are able to perform lossy compression on the motion data without noticeable degradation in rendered qualities. While achieving real-time performance, our technique outperforms other methods in our experiments by achieving a compression ratio exceeding 50 : 1 on regular sequences.