Volume 23 (2004)

Permanent URI for this community

https://diglib.eg.org/handle/10.2312/113

Browse

Now showing 1 - 20 of 93

High Resolution Acquisition, Learning and Transfer of Dynamic 3-D Facial Expressions
(The Eurographics Association and Blackwell Publishing, Inc, 2004) Wang, Yang; Huang, Xiaolei; Lee, Chan-Su; Zhang, Song; Li, Zhiguo; Samaras, Dimitris; Metaxas, Dimitris; Elgammal, Ahmed; Huang, Peisen
Synthesis and re-targeting of facial expressions is central to facial animation and often involves significant manual work in order to achieve realistic expressions, due to the difficulty of capturing high quality dynamic expression data. In this paper we address fundamental issues regarding the use of high quality dense 3-D data samples undergoing motions at video speeds, e.g. human facial expressions. In order to utilize such data for motion analysis and re-targeting, correspondences must be established between data in different frames of the same faces as well as between different faces. We present a data driven approach that consists of four parts: 1) High speed, high accuracy capture of moving faces without the use of markers, 2) Very precise tracking of facial motion using a multi-resolution deformable mesh, 3) A unified low dimensional mapping of dynamic facial motion that can separate expression style, and 4) Synthesis of novel expressions as a combination of expression styles. The accuracy and resolution of our method allows us to capture and track subtle expression details. The low dimensional representation of motion data in a unified embedding for all the subjects in the database allows for learning the most discriminating characteristics of each individual's expressions as that person's 'expression style'. Thus new expressions can be synthesized, either as dynamic morphing between individuals, or as expression transfer from a source face to a target face, as demonstrated in a series of experiments.Categories and Subject Descriptors (according to ACM CCS): I.3.7 [Computer Graphics]: Animation; I.3.5 [Computer Graphics]: Curve, surface, solid, and object representations; I.3.3 [Computer Graphics]: Digitizing and scanning; I.2.10 [Artificial intelligence]: Motion ; I.2.10 [Artificial intelligence]: Representations, data structures, and transforms; I.2.10 [Artificial intelligence]: Shape; I.2.6 [Artificial intelligence]: Concept learning
Instant Volumetric Understanding with Order-Independent Volume Rendering
(The Eurographics Association and Blackwell Publishing, Inc, 2004) Mora, Benjamin; Evert, David S.
Rapid, visual understanding of volumetric datasets is a crucial outcome of a good volume rendering application, but few current volume rendering systems deliver this result. Our goal is to reduce the volumetric surfing that is required to understand volumetric features by conveying more information in fewer images. In order to achieve this goal, and in contrast with most current methods which still use optical models and alpha blending, our approach reintroduces the order-independent contribution of every sample along the ray in order to have an equiprobable visualization of all the volume samples. Therefore, we demonstrate how order independent sampling can be suitable for fast volume understanding, show useful extensions to MIP and X-ray like renderings, and, finally, point out the special advantage of using stereo visualization in these models to circumvent the lack of depth cues.Categories and Subject Descriptors: I.3.3 [Computer Graphics]: Picture/Image, Generation,I.3.7 [Computer Graphics]: Three-Dimensional graphics and realism.
Computing Maximal Tiles and Application to Impostor-Based Simplification
(The Eurographics Association and Blackwell Publishing, Inc, 2004) Andujar, C.; Brunet, P.; Chica, A.; Navazo, I.; Rossignac, J.; Vinacua, A.
The computation of the largest planar region approximating a 3D object is an important problem with wide applications in modeling and rendering. Given a voxelization of the 3D object, we propose an efficient algorithm to solve a discrete version of this problem. The input of the algorithm is the set of grid edges connecting the interior and the exterior of the object (called sticks). Using a voting-based approach, we compute the plane that slices the largest number of sticks and is orientation-compatible with these sticks. The robustness and efficiency of our approach rests on the use of two different parameterizations of the planes with suitable properties. The first of these is exact and is used to retrieve precomputed local solutions of the problem. The second one is discrete and is used in a hierarchical voting scheme to compute the global maximum. This problem has diverse applications that range from finding object signatures to generating simplified models. Here we demonstrate the merits of the algorithm for efficiently computing an optimized set of textured impostors for a given polygonal model.Categories and Subject Descriptors (according to ACM CCS): I.3.5 [Computer Graphics]: Computational Geometry and Object Modeling
Crowd of Virtual Humans: a New Approach for Real Time Navigation in Complex and Structured Environments
(The Eurographics Association and Blackwell Publishing, Inc, 2004) Lamarche, Fabrice; Donikian, Stephane
The navigation activity is an every day practice for any human being capable of locomotion. Our objective in this work is to reproduce this crucial human activity inside virtual environments. Putting together the high complexity of a realistic environment such as a city, a big amount of virtual humans and the real-time constraint requires to optimize each aspect of the animation process. In this paper, we present a suitable topological structuring of the geometric environment to allow fast path finding as well as an efficient reactive navigation algorithm for virtual humans evolving inside a crowd.
The Design of an Inexpensive Very High Resolution Scan Camera System
(The Eurographics Association and Blackwell Publishing, Inc, 2004) Wang, Shuzhen; Heidrich, Wolfgang
Hierarchical Retargetting of Fine Facial Motions
(The Eurographics Association and Blackwell Publishing, Inc, 2004) Na, Kyunggun; Jung, Moonryul
We present a novel technique for retargetting captured facial animation to new facial models. We use dense motion data that can express fine motions such as wrinkles. We use a normal mesh, which is a special multi-resolution mesh, to represent source and target models. A normal mesh is defined by the base mesh and sequence of normal offsets from it. Our retargetting consists of two steps: base mesh and detail mesh retargetting. For base mesh retargetting, we use an example-based technique to take advantage of the intuition of the user in specifying the similarity between source and target expressions. In detail mesh retargetting, the variations of normal offsets in the source mesh are hierarchically computed and transferred to the target mesh. Our retargetting scheme is able to produce robust and delicate results for unusual target models from highly detailed motion data.Categories and Subject Descriptors (according to ACM CCS): I.3.7 [Computer Graphics]: Three Dimensional Graphics and Realism - Animation; I.3.5 [Computer Graphics]: Computational Geometry and Object Modelling - hierarchy and geometric transformation, object hierarchy
Topological Construction and Visualization of Higher Order 3D Vector Fields
(The Eurographics Association and Blackwell Publishing, Inc, 2004) Weinkauf, Tino; Theisel, Holger; Hege, Hans-Christian; Seidel, Hans-Peter
We present the first algorithm for constructing 3D vector fields based on their topological skeleton. The skeleton itself is modeled by interactively moving a number of control polygons. Then a piecewise linear vector field is automatically constructed which has the same topological skeleton as modeled before. This approach is based on a complete segmentation of the areas around critical points into sectors of different flow behavior. Based on this, we present the first approach to visualizing higher order critical points of 3D vector fields.Categories and Subject Descriptors (according to ACM CCS): I.3.3 [Computer Graphics]: Line and Curve Generation I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism
Way-Finder: guided tours through complex walkthrough models
(The Eurographics Association and Blackwell Publishing, Inc, 2004) Andujar, C.; Vazquez, P.; Fairen, M.
The exploration of complex walkthrough models is often a difficult task due to the presence of densely occluded regions which pose a serious challenge to online navigation. In this paper we address the problem of algorithmic generation of exploration paths for complex walkthrough models. We present a characterization of suitable properties for camera paths and we discuss an efficient algorithm for computing them with little or no user intervention. Our approach is based on identifying the free-space structure of the scene (represented by a cell and portal graph) and an entropy-based measure of the relevance of a view-point. This metric is key for deciding which cells have to be visited and for computing critical way-points inside each cell. Several results on different model categories are presented and discussed.
Applied Geometry:Discrete Differential Calculus for Graphics
(The Eurographics Association and Blackwell Publishing, Inc, 2004) Desbrun, Mathieu
Geometry has been extensively studied for centuries, almost exclusively from a differential point of view. However, with the advent of the digital age, the interest directed to smooth surfaces has now partially shifted due to the growing importance of discrete geometry. From 3D surfaces in graphics to higher dimensional manifolds in mechanics, computational sciences must deal with sampled geometric data on a daily basis-hence our interest in Applied Geometry.In this talk we cover different aspects of Applied Geometry. First, we discuss the problem of Shape Approximation, where an initial surface is accurately discretized (i.e., remeshed) using anisotropic elements through error minimization. Second, once we have a discrete geometry to work with, we briefly show how to develop a full- blown discrete calculus on such discrete manifolds, allowing us to manipulate functions, vector fields, or even tensors while preserving the fundamental structures and invariants of the differential case. We will emphasize the applicability of our discrete variational approach to geometry by showing results on surface parameterization, smoothing, and remeshing, as well as virtual actors and thin-shell simulation.Joint work with: Pierre Alliez (INRIA) , David Cohen-Steiner (Duke U.), Eitan Grinspun (NYU), Anil Hirani (Caltech), Jerrold E. Marsden (Caltech), Mark Meyer (Pixar), Fred Pighin (USC), Peter Schroeder (Caltech), Yiying Tong (USC).
New Eurographics Fellows
(The Eurographics Association and Blackwell Publishing Ltd., 2004)
Eurographics Symposium on Rendering 2003
(The Eurographics Association and Blackwell Publishing Ltd., 2004) Lagae, Ares; Masselus, Vincent; Dutre, Philip
Distributed and Collaborative Visualization
(The Eurographics Association and Blackwell Publishing Ltd., 2004) Brodlie, K. W.; Duce, D. A.; Gallop, J. R.; Walton, J. P. R. B.; Wood, J. D.
Visualization is a powerful tool for analyzing data and presenting results in science, engineering and medicine. This paper reviews ways in which it can be used in distributed and/or collaborative environments. Distributed visualization addresses a number of resource allocation problems, including the location of processing close to data for the minimization of data traffic. The advent of the Grid Computing paradigm and the link to Web Services provides fresh challenges and opportunities for distributed visualization-including the close coupling of simulations and visualizations in a steering environment. Recent developments in collaboration have seen the growth of specialized facilities (such as Access Grid) which have supplemented traditional desktop video conferencing using the Internet and multicast communications. Collaboration allows multiple users-possibly at remote sites-to take part in the visualization process at levels which range from the viewing of images to the shared control of the visualization methods. In this review, we present a model framework for distributed and collaborative visualization and assess a selection of visualization systems and frameworks for their use in a distributed or collaborative environment. We also discuss some examples of enabling technology and review recent work from research projects in this field.
Simulating and modeling lichen growth
(The Eurographics Association and Blackwell Publishing, Inc, 2004) Desbenoit, Brett; Galin, Eric; Akkouche, Samir
This paper presents a system for modeling lichens and simulating their propagation and growth in a virtual scene. Lichens colonize almost every substrate in nature and play an important role in the visual appearance of a natural object. The propagation of lichens over the substrate is performed by an Open Diffusion Limited Aggregation model constrained by the characteristics of the environment. The designer can control the development of lichens with simple parameters. Rendering the complex geometry and texture of lichens is achieved by instantiating three dimensional lichen models stored in an atlas of shapes created after real world images. The lichens obtained by our approach considerably increase the realism of complex natural scenes.Categories and Subject Descriptors (according to ACMCCS):I.3.3 [Computer Graphics]:Three-Dimensional Graphics and Realism
Dye Advection Without the Blur: A Level-Set Approach for Texture-Based Visualization of Unsteady Flow
(The Eurographics Association and Blackwell Publishing, Inc, 2004) Weiskopf, D.
Dye advection is an intuitive and versatile technique to visualize both steady and unsteady flow. Dye can be easily combined with noise-based dense vector field representations and is an important element in user-centric visual exploration processes. However, fast texture-based implementations of dye advection rely on linear interpolation operations that lead to severe diffusion artifacts. In this paper, a novel approach for dye advection is proposed to avoid this blurring and to achieve long and clearly defined streaklines or extended streak-like patterns. The interface between dye and background is modeled as a level-set within a signed distance field. The level-set evolution is governed by the underlying flow field and is computed by a semi-Lagrangian method. A reinitialization technique is used to counteract the distortions introduced by the level-set evolution and to maintain a level-set function that represents a local distance field. This approach works for 2D and 3D flow fields alike. It is demonstrated how the texture-based level-set representation lends itself to an efficient GPU implementation and therefore facilitates interactive visualization.Categories and Subject Descriptors (according to ACM CCS): I.3.3 [Computer Graphics]: Picture/Image Generation I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism
Deferred Splatting
(The Eurographics Association and Blackwell Publishing, Inc, 2004) Guennebaud, Gael; Barthe, Loic; Paulin, Mathias
In recent years it has been shown that, above a certain complexity, points become the most efficient rendering primitives. Although the programmability of the lastest graphics hardware allows efficient implementation of high quality surface splatting algorithms, their performance remains below those obtained with simpler point based rendering algorithms when they are used for scenes of high complexity. In this paper, our goal is to apply high quality point based rendering algorithms on complex scenes. For this purpose, we show how to take advantage of temporal coherency in a very accurate hardware accelerated point selection algorithm allowing the expensive computations to be peformed only on visible points. Our algorithm is based on a multi-pass hardware accelerated EWA splatting. It is also suitable for any rendering application since no pre-process is needed and no assumption is made on the data structure. In addition, we briefly discuss the association of our method with other existing culling techniques and optimization for particular applications.Categories and Subject Descriptors (according to ACM CCS): I.3.3 [Computer Graphics]: Viewing algorithms
Fast Surface Modelling Using a 6th Order PDE
(The Eurographics Association and Blackwell Publishing, Inc, 2004) Zhang, Jian. J.; You, L. H.
Although the control-point based parametric approach is used most widely in free-form surface modelling, complementary techniques co-exist to meet various specialised requirements. The partial differential equation (PDE) based modelling approach is especially suitable for satisfying surface boundary constraints. They are also effective for the generation of families of free-form surfaces, which share a common base and differ in their secondary features. In this paper, we present a fast surface modelling method using a sixth order PDE. This PDE provides enough degrees of freedom not only to accommodate tangent, but also curvature boundary conditions and offers more shape control parameters to serve as user controls for the manipulation of surface shapes. In order to achieve real-time performance, we have constructed a surface function and developed a high-precision approximate solution to the 6th order PDE. Unlike some existing PDE-based techniques, this resolution method can satisfy the boundary conditions exactly, and is able to create free-form surfaces as fast and almost as accurately as the closed-form (analytical) solutions. Due to the fact that it has sufficient degrees of freedom to accommodate the continuity of 3-sided and 4-sided surface patches at their boundaries, this method is able to model complex surfaces consisting of multiple patches. Compared with existing PDE-based modelling methods, this method is both fast and can solve a larger class of surface modelling problems.Categories and Subject Descriptors (according to ACM CCS): I.3.5 [Computer Graphics]: Curves, surfaces, solid, and object representations; physically based modelling
Measurement-Based Interactive Simulation of Viscoelastic Solids
(The Eurographics Association and Blackwell Publishing, Inc, 2004) Schoner, Jeffrey L.; Lang, Jochen; Seidel, Hans-Peter
Animation of viscoelastic solids in entertainment and medical applications as well as scientific simulation can be improved through observations of real world objects. This paper presents a method for simulating viscoelastic solids in real-time for visual and haptic display along with a method for determining the parameters of the the underlying model from automated physical measurements of real world objects. The viscoelastic model is a novel extension of the discrete Green's function matrix for linear elasticity, which combines static behavior represented by Green's functions with dynamic behavior expressed by differential equations inspired by particle systems. We describe a novel estimation method of dynamic contact behavior for heterogeneous complex objects based on these measurements. For this estimation, our method relies only on measurement data previously used in the acquisition less realistic elastostatic models. In this way our method allows more physically accurate realism in animation of viscoelastic solids without large additional computational costs or any measurements besides those associated with related methods for elastostatic solids.Categories and Subject Descriptors (according to ACM CCS): I.3.5 [Computer Graphics]: Physically based modeling I.3.7 [Computer Graphics]: Virtual reality, animation
Approximated Centroidal Voronoi Diagrams for Uniform Polygonal Mesh Coarsening
(The Eurographics Association and Blackwell Publishing, Inc, 2004) Valette, Sebastien; Chassery, Jean-Marc
We present a novel clustering algorithm for polygonal meshes which approximates a Centroidal Voronoi Diagram construction. The clustering provides an efficient way to construct uniform tessellations, and therefore leads to uniform coarsening of polygonal meshes, when the output triangulation has many fewer elements than the input mesh. The mesh topology is also simplified by the clustering algorithm. Based on a mathematical framework, our algorithm is easy to implement, and has low memory requirements. We demonstrate the efficiency of the proposed scheme by processing several reference meshes having up to 1 million triangles and very high genus within a few minutes on a low- end computer.
Second Annual Symposium on Computer Animation (SCA 2003)
(The Eurographics Association and Blackwell Publishing Ltd., 2004) SCA 2003 Chairs
Rendering with Spherical Radiance Transport Maps
(The Eurographics Association and Blackwell Publishing, Inc, 2004) Mei, Chunhui; Shi, Jiaoying; Wu, Fuli
In this paper, we propose a real-time method for rendering soft shadows and inter-reflections of dynamic objects under complex illumination. In previous methods, many efforts were taken to acquire occlusion and reflection informations for dynamic scene on the fly, and the result image cannot be generated in real time. In our approach, these informations for each object are pre-computed and stored in well-defined Spherical Radiance Transport Maps (SRTMs). For distant complex illumination such as environment illumination and area light source, we decompose the illumination to several hundred directional lights. In rendering, we search in SRTMs for occlusion info which may cause shadows, and reflection info which may cause inter-reflections. Finally we produce realistic soft shadows and inter-reflections efficiently. Our method is related with but different from previous Pre-computed Radiance Transfer techniques which are only suitable for static scene.Categories and Subject Descriptors (according to ACM CCS): I.3.7 [Computer Graphics]: shading and shadowing

Browse

Browsing Volume 23 (2004) by Issue Date

Results Per Page

Sort Options