Short Presentations 2006

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https://diglib.eg.org/handle/10.2312/255

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Articulated Video Sprites
(The Eurographics Association, 2006) Vanaken, C.; Gerrits, M.; Bekaert, P.; Dieter Fellner and Charles Hansen
In this paper, we present an extension to video sprites for articulated characters. Central to our technique is a matching cost which works on high-level 2D skeletal representations of the characters, instead of their visual appearance. Through a combination of different heuristics, we are able to animate a character according to a new sequence of target skeletons. This way we achieve an accurate matching and a hitherto unseen level of control over the video sprite.
Automatic Depth-Map Colorization
(The Eurographics Association, 2006) Hassner, T.; Basri, R.; Dieter Fellner and Charles Hansen
We present a system for automatically generating custom, structured image-maps for input depth-maps. Our system thus allows quick fitting of masses of objects with tailor-made image-maps. Given a depth-map of a novel 3D object, our method tiles it with intensities from similar, pre-collected, textured objects. These are seamlessly merged to form the new image-map. This process is performed by optimizing a well defined target likelihood function, via a hard-EM procedure. We present results for varied object classes including human figures, and fish.
Clothing the Masses: Real-Time Clothed Crowds With Variation
(The Eurographics Association, 2006) Dobbyn, S.; McDonnell, R.; Kavan, L.; Collins, S.; O'Sullivan, C.; Dieter Fellner and Charles Hansen
The animation and rendering of crowds of realistically clothed characters presents a difficult challenge in computer graphics, which is further exacerbated when real-time frame rates are required. To date, due to real-time constraints, standard skinning methods have been used to animate the clothes of individuals in real-time crowds, which does not create the appropriate secondary motion for flowing garments. However, plausible cloth simulation is vital for the depiction of realistic characters, so we have developed a novel crowd system in which the individuals are endowed with realism and variety through the addition of physically simulated clothing and hardware assisted pattern variation.
Competitive Runtime Performance for Inverse Kinematics Algorithms using Conformal Geometric Algebra
(The Eurographics Association, 2006) Hildenbrand, Dietmar; Fontijne, Daniel; Wang, Yusheng; Alexa, Marc; Dorst, Leo; Dieter Fellner and Charles Hansen
Conformal geometric algebra is a powerful tool to find geometrically intuitive solutions. We present an approach for the combination of compact and elegant algorithms with the generation of very efficient code based on two different optimization approaches with different advantages, one is based on Maple, the other one is based on the code generator Gaigen 2. With these results, we are convinced that conformal geometric algebra will be able to become fruitful in a great variety of applications in Computer Graphics.
Connectivity-Aware Sectional Visualization of 3D DTI Volumes using Perceptual Flat-Torus Coloring and Edge Rendering
(The Eurographics Association, 2006) Demiralp, Çagatay; Zhang, Song; Tate, David F.; Correia, Stephen; Laidlaw, David H.; Dieter Fellner and Charles Hansen
We present two new methods for visualizing cross-sections of 3D diffusion tensor magnetic resonance imaging (DTI) volumes. For each of the methods we show examples of visualizations of the corpus callosum in the midsagittal plane of several normal volunteers. In both methods, we start from points sampled on a regular grid on the cross-section and, from each point, generate integral curves in both directions following the principal eigenvector of the underlying diffusion tensor field.We compute an anatomically motivated pairwise distance measure between each pair of integral curves and assemble the measures to create a distance matrix. We next find a set of points in a plane that best preserves the calculated distances that are small each point in this plane represents one of the original integral curves. Our first visualization method wraps this planar representation onto a flat-torus and then projects that torus into a visible portion of a perceptually uniform color space (L*a*b*). The colors for the paths are used to color the corresponding grid points on the original cross-section. The resulting image shows larger changes in color where neighboring integral curves differ more. Our second visualization method lays out the grid points on the cross section and connects the neighboring points with edges that are rendered according to the distances between curves generated from these points. Both methods provide a way to visually segment 2D cross sections of DTI data. Also, a particular contribution of the coloring technique used in our first visualization method is to give a continuous 2D color mapping that provides approximate perceptual uniformity and can be repeated an arbitrary number of times in both directions to increase sensitivity.
Digital HPO Hologram Rendering Pipeline
(The Eurographics Association, 2006) Janda, M.; Hanák, I.; Skala, V.; Dieter Fellner and Charles Hansen
This paper describes a rendering pipeline for digital hologram synthesis. The pipeline is capable of handling triangle meshes, directional light sources, texture coordinates, and advanced illumination models. Due to the huge computational requirements of hologram synthesis only the HPO holograms are considered.
Dynamic Anisotropic Occlusion
(The Eurographics Association, 2006) Gong, Yi; Zhang, Yubo; Chen, Wei; Peng, Qunsheng; Dieter Fellner and Charles Hansen
We present a new real-time shadow rendering approach whose kernel is a hierarchical disk-based approximation to the scene geometry. We show that this approximated representation greatly accelerates the visibility inquiry, facilitating the real-time computation of anisotropic occlusion in GPU. By taking account of anisotropic occlusion, our approach can simulate the shadow cast from not only ambient light, but also point, directional and environment lights. Because no pre-computation is required, it is suitable for dynamically deforming objects.
Elastic Facial Caricature Warping
(The Eurographics Association, 2006) Clarke, Lyndsey; Chen, Min; Townsend, Peter; Mora, Benjamin; Dieter Fellner and Charles Hansen
Caricatures are usually created by skilled artists, and, due to their amusing appearance, they serve mainly as a source of entertainment and humour. This short paper is therefore concerned with a means for generating facial caricatures from given photographs using image warping. In particular, we propose to assign virtual physical and material properties to various facial features in order to specify and render exaggerated transformations in an intuitive manner. Though our objective is not for creating physically accurate photorealism, our physically-based approach enables users to associate virtual displacements in caricatures, with common physical phenomena.
Enhanced Cartoon and Comic Rendering
(The Eurographics Association, 2006) Spindler, Martin; Röber, Niklas; Döhring, Robert; Masuch, Maic; Dieter Fellner and Charles Hansen
In this work we present an extension to common cel shading techniques, and describe four new cartoon-like rendering styles applicable for real-time implementations: stylistic shadows, double contour lines, soft cel shading, and pseudo edges. Our work was mainly motivated by the rich set of stylistic elements and expressional possibilities within the medium comic. In particular, we were inspired by Miller s Sin City and McFarlane s Spawn . We designed algorithms for these styles, developed a real-time implementation and integrated it into a regular 3D game engine.
Evaluation of Different Diffuse Surface Reflection Models for Global Illumination
(The Eurographics Association, 2006) Diepstraten, Joachim; Borgo, Rita; Dieter Fellner and Charles Hansen
One common goal nearly all global illumination algorithms aim for is solving the light transport problem. The most visual noticeable one in the general case is the diffuse-diffuse light transport between surfaces. Most global illumination algorithms are very good at solving it. In many global illumination solutions the Lambertian diffuse surface reflection model is assumed. However, over the years several other diffuse models have been introduced mostly outside of the computer graphics community that according to their authors mimic real surface behaviour more accurately. In this paper we evaluate some of the better known models and place them into the context of solving global illumination problems.
Exploring Flow Fields with GPU-Based Stream Tracers in Virtual Environments
(The Eurographics Association, 2006) Schirski, Marc; Bischof, Christian; Kuhlen, Torsten; Dieter Fellner and Charles Hansen
In this paper we present an immersive visualization approach for the intuitive exploration of flow fields, which operates entirely within the graphics subsystem. We augment particle data with a brief history of their recent positions, thus effectively computing and displaying animated tracers facilitating the understanding of the underlying flow field. Image quality is enhanced by employing a billboard-based rendering method for the particle trajectories simulating lit tubular geometry. This leads to significantly reduced depth perception problems and depth order ambiguities. Interactivity is maintained even for large amounts of tracers by shifting the computational load to the GPU. We alleviate 3D seed point specification problems by offering interaction mechanisms with full 6 degrees-of-freedom within an immersive virtual environment.
Fast and Realistic Display of Clouds Using a Recording Matrix
(The Eurographics Association, 2006) Wu, Y.; Allgöwer, B.; Nüesch, D.; Dieter Fellner and Charles Hansen
For volumetric cloud models, traditional ray tracing methods and graphics hardware acceleration methods can result in photorealistic images, but with considerably expensive costs. Hence, real-time rendering can be achieved only under the condition of a static relationship between light sources and clouds. This paper presents a new method to accelerate the rendering process for animated clouds. In order to display visually convincing self-shading properties of clouds, multiple scattering among their internal particles is taken into account with the help of a recording matrix, which only requires small intermediate saving space. This method is not only flexible and easy to use, but also capable of rendering other dynamic gaseous phenomena such as smoke in a fast and efficient manner.
Fast Skeletal Animation by skinned Arc-Spline based Deformation
(The Eurographics Association, 2006) Forstmann, Sven; Ohya, Jun; Dieter Fellner and Charles Hansen
Presented is a novel skeletal animation system for providing high quality geometric deformations in real-time. Each bone of the skeleton is therefore represented by a spline, rather than using conventional matrix rotation. In our approach, each vertex of the animated character can be influenced by a maximum of three spline-curves, which is sufficient for skinned animation. One spline is parameterized by three control points and a possible twist. As opposed to conventional Bézier curves does our arc-spline rely on trigonometric functions for providing better curvatures. The optimized implementation using the OpenGL-shading language shows very promising results for real-time character animation, as even about 1 Million vertices were able to be transformed at interactive 43 frames per second on a GeForce 7800 GTX graphics card.
GPU-Based Hierarchical Texture Decompression
(The Eurographics Association, 2006) Stachera, J.; Rokita, P.; Dieter Fellner and Charles Hansen
We propose a hierarchical texture compression algorithm for real-time decompression on the GPU. Our algorithm is characterized by low computational complexity, random access and hierarchical structure which allow us to access first three levels of encoded mip-map pyramid. The hierarchical texture compression algorithm HiTCg is based on block-wise approach, where each block is subject to local fractal transform.
Harnessing the Human Visual System for Image Based Modeling: an Interaction System
(The Eurographics Association, 2006) Morvan, Y.; O'Sullivan, C.; Dieter Fellner and Charles Hansen
We present a novel interaction system for modeling 3D geometry from photographs. Given a set of stereo pairs, along with their camera parameters, the interface tracks the movements of the users and allows them to intuitively position the modeling tools in 3D and to browse the stereo pairs using head movements. The geometry being modeled is overlaid on the photographs using a stereo display. The use of the known camera parameters for displaying the geometry ensures proper registration with each photograph and thus results in correct 3D models.
High Quality Shadows for Real-Time Crowds
(The Eurographics Association, 2006) Ryder, G.; Day, A. M.; Dieter Fellner and Charles Hansen
Real-time shadowed crowds, especially under locally lit environments, pose several distinct challenges. Current solutions for crowds are either very simplistic for multiple lights or only handle a single directional light with shadows. This work focuses on bringing hundreds of local lights with high fidelity shadows for crowds into the real-time domain. Each light is given the ability to cast shadows for all objects (dynamic and static) within the scene, and all the levels of detail used for representing the crowds correctly interact with the lighting conditions. In this paper we introduce depth augmented billboards for crowds, to allow for improved quality under local lights, including self-shadowing. Through use of the GPU fragment programs; this extension is entirely implemented on the graphics card for minimal performance impact.
HOPI: A Novel High Order Parametric Interpolation in 2D
(The Eurographics Association, 2006) Xu, Jia; Huang, Zhiyong; Dieter Fellner and Charles Hansen
This paper presents a novel smooth and convergent high order parametric interpolation method called HOPI with a formal treatment. It employs high order derivatives information and provides more freedom on control of curves. It can be applied to shape design and analysis using curves. This paper reports the work in 2D.
Lighting-Up Geometry: Accurate 3D Modelling of Museum Artifacts with a Torch and a Camera
(The Eurographics Association, 2006) Vogiatzis, G.; Hernández, C.; Cipolla, R.; Dieter Fellner and Charles Hansen
This paper addresses the problem of obtaining complete, very detailed reconstructions of shiny objects such as glazed ceramics. We present an algorithm which uses silhouettes of the object, as well as images obtained under changing illumination conditions. In contrast with previous photometric stereo techniques, ours is not limited to a single viewpoint but produces accurate reconstructions in full 3D. A number of images of the object are obtained from multiple viewpoints, under varying lighting conditions. Starting from the silhouettes, the algorithm recovers camera motion and constructs the object s visual hull. This is then used to recover the illumination and initialise a multi-view photometric stereo scheme to obtain a closed surface reconstruction. The algorithm has been implemented as a practical model acquisition system. Here, we present a number of complete reconstructions of challenging real objects.
m-LOMA - a Mobile 3D Portal to Location-based Information
(The Eurographics Association, 2006) Nurminen, Antti; Dieter Fellner and Charles Hansen
We present a novel application, a mobile 3D city map, with a capability to render dozens of textured buildings at interactive rates in desktop machines, PDA devices and mart phones. The system allows annotation of the virtual environment by content databases and user-spesified messages, which also act as bulletinboards, and supports avigation with GPS locationing and routing. As a key enabler, a 3D engine suited for urban environments is developed. A lightweight but realistic model consisting of an ntire city center with over 300 buildings is created. The application design, features and implementation are presented, along with results regarding performance and reliminary field studies.
Magical Mirrors
(The Eurographics Association, 2006) Michelis, D.; Send, H.; Resatsch, F.; Schildhauer, T.; Dieter Fellner and Charles Hansen
This article describes the multi-media art installation MAGICAL MIRRORS with which the tradition of the mirror, as a medium of visual simulation, is carried over into the world of digital mediums. As theoretical framework, the basic principle of remediation as described by Bolter and Grusin is utilized. According to this theory new media technologies always represent the advancements of prior media that are either enhanced in order to upgrade the features or replaced entirely. MAGICAL MIRRORS follows in the tradition of the magical mirror found in palaces or amusement parks. Like their predecessors they awaken the curiosity of the viewer and invite him or her on a trip into virtual worlds.

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