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Now showing 1 - 10 of 18
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    RTSG: Ray Tracing for X3D via a Flexible Rendering Framework
    (The Eurographics Association, 2009) Rubinstein, Dmitri; Georgiev, Iliyan; Schug, Benjamin; Slusallek, Philipp; Dieter W. Fellner and Alexei Sourin and Johannes Behr and Krzysztof Walczak
    VRML and X3D are the most widely adopted standards for interactive 3D content interchange. However, they are both designed around the common restricted functionality available in hardware graphics processors. Thus, most existing scene graph implementations are tightly integrated with rasterization APIs, which have difficulties simulating advanced global lighting effects. Conversely, complex photo-realistic effects are naturally supported by ray tracing based rendering algorithms [Glassner 1989]. Due to recent research advances and the constantly increasing computing power of commodity PCs, ray tracing is emerging as an interesting alternative for interactive applications. In this paper we present RTSG (Real-Time Scene Graph), a flexible scene management and rendering system. RTSG is X3D-compliant and has been designed to efficiently support both ray tracing and rasterization using a backend-independent rendering infrastructure. We describe two ray tracing and one rasterization backends and demonstrate that they achieve real-time rendering performance.
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    Anisotropic Friction for Deformable Surfaces and Solids
    (ACM SIGGRAPH / Eurographics Association, 2009) Pabst, Simon; Thomaszewski, Bernhard; StraĂźer, Wolfgang; Eitan Grinspun and Jessica Hodgins
    This paper presents a method for simulating anisotropic friction for deforming surfaces and solids. Frictional contact is a complex phenomenon that fuels research in mechanical engineering, computational contact mechanics, composite material design and rigid body dynamics, to name just a few. Many real-world materials have anisotropic surface properties. As an example, most textiles exhibit direction-dependent frictional behavior, but despite its tremendous impact on visual appearance, only simple isotropic models have been considered for cloth and solid simulation so far. In this work, we propose a simple, application-oriented but physically sound model that extends existing methods to account for anisotropic friction. The sliding properties of surfaces are encoded in friction tensors, which allows us to model frictional resistance freely along arbitrary directions. We also consider heterogeneous and asymmetric surface roughness and demonstrate the increased simulation quality on a number of two- and three-dimensional examples. Our method is computationally efficient and can easily be integrated into existing systems.
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    A Processing Pipeline for X3D Earth-based Spatial Data View Services
    (The Eurographics Association, 2009) Reitz, Thorsten; Krämer, Michel; Thum, Simon; Dieter W. Fellner and Alexei Sourin and Johannes Behr and Krzysztof Walczak
    Over the last years, a high demand for scenario-specific visualizations of 3D urban models has evolved. At the same time, established service specifications do not yet provide the means to define 3D map products and to deliver them in suitable formats, since they are focused on traditional 2D map products. In this paper, we present an approach for the definition of a 3D urban model view service. This approach consists of a three-step process, in which original geodata is integrated, filtered and then transformed into various scene graph formats such as X3D. We were able to maintain a high degree of compatibility with existing services and specifications such as Styled Layer Descriptors and the Web Map Service interface. The paper concludes with the experiences gathered from implementing and using this approach and provides an outlook as to how the lessons learned can be used in application and standardization.
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    Extending X3D for Distributed Multimedia Processing and Control
    (The Eurographics Association, 2009) Repplinger, Michael; Löffler, Alexander; Schug, Benjamin; Slusallek, Philipp; Dieter W. Fellner and Alexei Sourin and Johannes Behr and Krzysztof Walczak
    Web-based applications of interactive 3D computer graphics are showing a tendency to get more interconnected and visually complex. Virtual communities like Second Life demand realism not only in terms of realistic rendering, but also in terms of integrated multimedia content. For these Web-based applications, X3D is the ISO-standard way to specify and manipulate scene descriptions. In terms of multimedia integration, however, X3D offers to specify content only in the form of URLs pointing to files. Modern middleware for distributed multimedia, on the other hand, allows applications to harness the full range of multimedia processing as well as transparent use and full control of both local and remote components. Integrating a full multimedia processing pipeline into X3D would enable Web authors to use, for example, streaming media, post-processing on media streams, or routing between scene elements (e.g., sensors) and elements of multimedia processing (e.g., TV cards). A full integration of multimedia in X3D is yet missing. In this paper, we propose X3D extensions for a seamless mapping of a distributed multimedia flow graph onto an X3D scene graph, making all the features of a distributed multimedia middleware accessible and usable within an X3D scene. We present our proposed specification and implementation of multimedia nodes for X3D. Using examples and implemented X3D application scenarios, we show the simplicity and feasibility of our approach.
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    A Point-based Method for Animating Incompressible Flow
    (ACM SIGGRAPH / Eurographics Association, 2009) Sin, Funshing; Bargteil, Adam W.; Hodgins, Jessica K.; Eitan Grinspun and Jessica Hodgins
    In this paper, we present a point-based method for animating incompressible flow. The advection term is handled by moving the sample points through the flow in a Lagrangian fashion. However, unlike most previous approaches, the pressure term is handled by performing a projection onto a divergence-free field. To perform the pressure projection, we compute a Voronoi diagram with the sample points as input. Borrowing from Finite Volume Methods, we then invoke the divergence theorem and ensure that each Voronoi cell is divergence free. To handle complex boundary conditions, Voronoi cells are clipped against obstacle boundaries and free surfaces. The method is stable, flexible and combines many of the desirable features of point-based and grid-based methods. We demonstrate our approach on several examples of splashing and streaming liquid and swirling smoke.
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    Spatial Deformation Transfer
    (ACM SIGGRAPH / Eurographics Association, 2009) Ben-Chen, Mirela; Weber, Ofir; Gotsman, Craig; Eitan Grinspun and Jessica Hodgins
    Much effort is invested in generating natural deformations of three-dimensional shapes. Deformation transfer simplifies this process by allowing to infer deformations of a new shape from existing deformations of a similar shape. Current deformation transfer methods can be applied only to shapes which are represented as a single component manifold mesh, hence their applicability to real-life 3D models is somewhat limited. We propose a novel deformation transfer method, which can be applied to a variety of shape representations tet-meshes, polygon soups and multiple-component meshes. Our key technique is deformation of the space in which the shape is embedded. We approximate the given source deformation by a harmonic map using a set of harmonic basis functions. Then, given a sparse set of user-selected correspondence points between the source and target shapes, we generate a deformation of the target shape which has differential properties similar to those of the source deformation. Our method requires only the solution of linear systems of equations, and hence is very robust and efficient. We demonstrate its applicability on a wide range of deformations, for different shape representations.
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    A Point-Based Method for Animating Elastoplastic Solids
    (ACM SIGGRAPH / Eurographics Association, 2009) Gerszewski, Dan; Bhattacharya, Haimasree; Bargteil, Adam W.; Eitan Grinspun and Jessica Hodgins
    In this paper we describe a point-based approach for animating elastoplastic materials. Our primary contribution is a simple method for computing the deformation gradient for each particle in the simulation. The deformation gradient is computed for each particle by finding the affine transformation that best approximates the motion of neighboring particles over a single timestep. These transformations are then composed to compute the total deformation gradient that describes the deformation around a particle over the course of the simulation. Given the deformation gradient we can apply arbitrary constitutive models and compute the resulting elastic forces. Our method has two primary advantages: we do not store or compare to an initial rest configuration and we work directly with the deformation gradient. The first advantage avoids poor numerical conditioning and the second naturally leads to a multiplicative model of deformation appropriate for finite deformations. We demonstrate our approach on a number of examples that exhibit a wide range of material behaviors.
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    Style Learning and Transferring for Facial Animation Editing
    (ACM SIGGRAPH / Eurographics Association, 2009) Ma, Xiaohan; Le, Binh Huy; Deng, Zhigang; Eitan Grinspun and Jessica Hodgins
    Most of current facial animation editing techniques are frame-based approaches (i.e., manually edit one keyframe every several frames), which is ineffective, time-consuming, and prone to editing inconsistency. In this paper, we present a novel facial editing style learning framework that is able to learn a constraint-based Gaussian Process model from a small number of facial-editing pairs, and then it can be effectively applied to automate the editing of the remaining facial animation frames or transfer editing styles between different animation sequences. Comparing with the state of the art, multiresolution-based mesh sequence editing technique, our approach is more flexible, powerful, and adaptive. Our approach can dramatically reduce the manual efforts required by most of current facial animation editing approaches.
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    Proposed Enhancements to the X3D Geospatial Component
    (The Eurographics Association, 2009) McCann, Michael; Puk, Richard; Hudson, Alan; Melton, Rex; Brutzman, Don; Dieter W. Fellner and Alexei Sourin and Johannes Behr and Krzysztof Walczak
    The Geospatial Component of the X3D Standard suffers from some deficiencies that prevent its wider adoption. This paper addresses two of these deficiencies. The first problem is that in order to reduce spatial jitter content must be built with regionally defined GeoOrigin nodes. This approach is fine for localized regional geospatial data visualization requirements, but fails for accurately viewing data in a global context or for combining content with different GeoOrigins. The second problem is the limited options for providing terrain data to the browser for rendering. The GeoLOD node is not the optimal solution for allowing the X3D browser to render terrain data in a high performing manner. This paper presents solutions to these problems for consideration by the Web3D community.
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    X3DOM - A DOM-based HTML5/ X3D Integration Model
    (The Eurographics Association, 2009) Behr, Johannes; Eschler, Peter; Jung, Yvonne; Zöllner, Michael; Dieter W. Fellner and Alexei Sourin and Johannes Behr and Krzysztof Walczak
    We present a model that allows to directly integrate X3D nodes into HTML5 DOM content. This model tries to fulfill the promise of the HTML5 specification, which references X3D for declarative 3D scenes but does not define a specific integration mode. The goal of this model is to ease the integration of X3D in modern web applications by directly mapping and synchronizing live DOM elements to a X3D scene model. This is a very similar approach to the current SVG integration model for 2D graphics. Furthermore, we propose a framework that includes a new X3D Profile for the DOM integration. This profile should make implementation simple, but in addition we show that the current X3D runtime model still scales well. A detailed discussion includes DOM integration issues like events, namespaces and scripting. We finally propose an implementation framework that should work with multiple browser frontends (e.g. Firefox andWebKit) and different X3D runtime backends. We hope to connect the technologies and the X3D/ W3C communities with this proposal and outline a model, how an integration without plugins could work. Moreover, we hope to inspire further work, which could lead to a native X3D implementation in browsers similar to the SVG implementations today.