EG2006

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https://diglib.eg.org/handle/10.2312/253

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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.
Toward the Light Field Display: Autostereoscopic Rendering via a Cluster of Projectors
(The Eurographics Association, 2006) Yang, Ruigang; Huang, Xinyu; Li, Sifang; Jaynes, Christopher; Dieter Fellner and Charles Hansen
Ultimately, a display device should be capable of reproducing the visual effects that are produced by reality. In this paper we introduce an autostereoscopic display that uses a scalable array of digital light projectors and a projection screen augmented with microlenses to simulate a light field for a given three-dimensional scene. Physical objects emit or reflect light in all directions to create a light field that can be approximated by the light field display. The display can simultaneously provide many viewers from different viewpoints a stereoscopic effect without head-tracking or special mechanical devices. We present a solution to automatically calibrate the light field display and an efficient algorithm to render the special multi-view images it requires by exploiting their spatial coherence. The effectiveness of our approach is demonstrated with a four-projector prototype that can display dynamic imagery with full parallax.
Collision Handling and its Applications
(The Eurographics Association, 2006) Teschner, Matthias; Cani, Marie-Paule; Fedkiw, Ron; Bridson, Robert; Redon, Stephane; Volino, Pascal; Zachmann, Gabriel; Nadia Magnenat-Thalmann and Katja Bühler
In contrast to real-world scenarios, object representations in virtual environments have no notion of interpenetration. Therefore, algorithms for the detection of interfering object representations are an essential component in virtual environments. Applications are wide-spread and can be found in areas such as surgery simulation, games, cloth simulation, and virtual prototyping. Early collision detection approaches have been presented in robotics and computational geometry more than twenty years ago. Nevertheless, collision detection is still a very active research topic in computer graphics. This ongoing interest is constantly documented by new results presented in journals and at major conferences, such as Siggraph and Eurographics. In order to enable a realistic behavior of interacting objects in dynamic simulations, collision detection algorithms have to be accompanied by collision response schemes.
Building Expression into Virtual Characters
(The Eurographics Association, 2006) Vinayagamoorthy, V.; Gillies, M.; Steed, A.; Tanguy, E.; Pan, X.; Loscos, C.; Slater, M.; Brian Wyvill and Alexander Wilkie
Virtual characters are an important part of many 3D graphical simulations. In entertainment or training applications, virtual characters might be one of the main mechanisms for creating and developing content and scenarios. In such applications the user may need to interact with a number of different characters that need to invoke specific responses in the user, so that the user interprets the scenario in the way that the designer intended. Whilst representations of virtual characters have come a long way in recent years, interactive virtual characters tend to be a bit "wooden" with respect to their perceived behaviour. In this STAR we give an overview of work on expressive virtual characters. In particular, we assume that a virtual character representation is already available, and we describe a variety of models and methods that are used to give the characters more "depth" so that they are less wooden and more plausible. We cover models of individual characters emotion and personality, models of interpersonal behaviour and methods for generating expression.
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.
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.
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.
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.
Solving Local Reflections: a Direct Methodology
(The Eurographics Association, 2006) Jeremias, P.; Chavarria, O.; Garcia, O.; Carrillo, X.; Cuñado, A.; Dieter Fellner and Charles Hansen
Reflection and refraction are key processes intended for realism within simulation platforms. There are several parameters related to those techniques whose values have been traditionally selected by using subjective criteria. This paper presents an interactive water rendering model where the adjustment of the local perturbation parameters has been revised, ensuring physical correctness. Therefore we present new tuning paradigms, based on physical, optical and, besides that, objective constraints.
Long Distance Distribution of Educational Augmented Reality Applications
(The Eurographics Association, 2006) Kaufmann, Hannes; Csisinko, Mathis; Totter, Alexandra; Judy Brown and Werner Hansmann
For distance education utilizing shared Virtual or Augmented Reality (VR/AR) applications, reliable network distribution of educational content is of prime importance. In this paper we summarize the development of software components enabling stable and reliable distribution of an existing educational AR application for geometry education. Our efforts focus on three main areas: (1) For long distance distribution of Open Inventor scene graphs, throughout a wide area IP network, a TCP based network protocol was implemented in Distributed Open Inventor. (2) A tracking middleware was extended to support sending tracking data unicast instead or in addition to sending multicast messages. (3) Multiple adaptations in our geometry application were required to improve scalability, robustness and reliability. We present an early evaluation with high school students in a distant learning, distributed HMD setup and highlight final results.
Efficient Sorting and Searching in Rendering Algorithms
(The Eurographics Association, 2006) Havran, Vlastimil; Bittner, Jiri; Nadia Magnenat-Thalmann and Katja Bühler
In the proposed tutorial we would like to highlight the connection between rendering algorithms and sorting and searching as classical problems studied in computer science. We will provide both theoretical and empirical evidence that for many rendering techniques most time is spent by sorting and searching. In particular we will discuss problems and solutions for visibility computation, density estimation, and importance sampling. For each problem we mention its specific issues such as dimensionality of the search domain or online versus offline searching. We will present the underlying data structures and their enhancements in the context of specific rendering algorithms such as ray shooting, photon mapping, and hidden surface removal.
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.
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.
Geometric Modeling Based on Triangle Meshes
(The Eurographics Association, 2006) Botsch, Mario; Pauly, Mark; Rössl, Christian; Bischoff, Stephan; Kobbelt, Leif; Nadia Magnenat-Thalmann and Katja Bühler
In the last years triangle meshes have become increasingly popular and are nowadays intensively used in many different areas of computer graphics and geometry processing. In classical CAGD irregular triangle meshes developed into a valuable alternative to traditional spline surfaces, since their conceptual simplicity allows for more flexible and highly efficient processing. Moreover, the consequent use of triangle meshes as surface representation avoids error-prone conversions, e.g., from CAD surfaces to meshbased input data of numerical simulations. Besides classical geometric modeling, other major areas frequently employing triangle meshes are computer games and movie production. In this context geometric models are often acquired by 3D scanning techniques and have to undergo postprocessing and shape optimization techniques before being actually used in production.This course discusses the whole geometry processing pipeline based on triangle meshes. We will first introduce general concepts of surface representations and point out the advantageous properties of triangle meshes in Section 2, and present efficient data structures for their implementation in Section 3. The different sources of input data and types of geometric and topological degeneracies and inconsistencies are described in Section 4, as well as techniques for their removal, resulting in clean two-manifold meshes suitable for further processing. Mesh quality criteria measuring geometric smoothness and element shape together with the corresponding analysis techniques are presented in Section 6. Mesh smoothing reduces noise in scanned surfaces by generalizing signal processing techniques to irregular triangle meshes (Section 7). Similarly, the underlying concepts from differential geometry are useful for surface parametrization as well (Section 8). Due to the enormous complexity of meshes acquired by 3D scanning, mesh decimation techniques are required for error-controlled simplification (Section 9). The shape of triangles, which is important for the robustness of numerical simulations, can be optimized by general remeshing methods (Section 10). After optimizing meshes with respect to the different quality criteria, we finally present techniques for intuitive and interactive shape deformation (Section 11). Since solving linear systems is a commonly required component for many of the presented mesh processing algorithms, we will discuss their efficient solution and compare several existing libraries in Section 12.
Rendering Plasma Phenomena: Applications and Challenges
(The Eurographics Association, 2006) Baranoski, G. V. G.; Rokne, J. G.; Brian Wyvill and Alexander Wilkie
Plasmas are ubiquitous in the Universe. An understanding of plasma phenomena is therefore of importance for almost every area of astrophysics, from stellar atmospheres to star clusters. Plasmas also occur in daily life both in industrial processes and in consumer products. Recent groundbreaking data is making this the golden age of plasma science. Although direct observations and analysis of data provide important physical evidence for plasma phenomena, they do not necessarily explain the phenomena. Hence, recent discoveries in this area might not only arise out of observations, but also from visual simulations of the phenomena supported by advanced rendering technologies. This report describes the state of art of such simulations, and examines practical issues often overlooked in the literature. Their educational and public outreach applications are also discussed. Although the emphasis is on the predictive rendering of plasma processes, the simulation guidelines and trade-offs addressed in this report can be extended to the general simulation of natural phenomena. The report closes with a discussion of further avenues of research involving the simulation of plasma phenomena.
3D Role-Playing Games as Language Learning Tools
(The Eurographics Association, 2006) Rankin, Yolanda; Gold, Rachel; Gooch, Bruce; Judy Brown and Werner Hansmann
Leveraging the experiential cognition and motivational factors of 3D games, we conduct a pilot study that utilizes Ever Quest 2 as pedagogical learning tool for English as a second language (ESL) students. We combine the benefits of massive multiplayer online role-playing games (MMORPGs) and second language methodology to create a digital learning environment for second language acquisition (SLA). Rather than using traditional computerassisted language learning (CALL) software, we explore the immersive, virtual environment of Ever Quest 2 as ESL participants assume virtual identities and engage in social interactions within the game world. We suggest that language becomes a crucial artifact for character development and completion of game tasks in the virtual world. Preliminary results demonstrate that Ever Quest 2 intermediate and advanced ESL students increase their English vocabulary by 40% as result of game play interactions with non-playing characters (NPCs). Furthermore, intermediate and advanced ESL students practice their conversational skills with playing characters (PCs), generating a 100% increase in chat messages during eight sessions of game play. These results lead to the conclusion that MMORPGs can provide motivation and adequate language learning support for intermediate and advanced ESL students.
Computer Graphics Applications in the Education Process of People with Learning Difficulties
(The Eurographics Association, 2006) Vera, Lucia; Campos, Ruben; Herrera, Gerardo; Sebastian, Beleu; Judy Brown and Werner Hansmann
This paper describes the use of Real Time graphic applications as educational tools, specifically oriented to working with people who have certain learning difficulties. We first focus on identifying the most relevant traits (from a psychological point of view) of those disorders, then we continue by analysing the advantages of graphics in Real Time in this context, and how they can be used to complement the conventional teaching methods. Finally, we review the main characteristics of two applications belonging to this category, which serve as a practical example of this encounter between education and technology.
A Perceptual Approach to Texture Scaling based on Human Computer Interaction
(The Eurographics Association, 2006) Cheng, Irene; Bischof, Walter; Dieter Fellner and Charles Hansen
The trade-off between texture quality and data size is often an important factor for online multimedia applications including 3D games, virtual reality, as well as for applications designed for portable devices. Although a number of state-of-the-art texture compression techniques have been proposed in the literature, there is little research on optimal resolution reduction, and especially on how the human visual system responds to texture scaling. In this paper, we investigate the visual discrimination of scaled textures and the threshold above which quality improvement is imperceptible. A perceptual approach based on human computer interaction is proposed along with its applications. Our contribution lies in introducing texture scaling over and above texture compression in order to achieve more efficient data transmission and quality preservation.
Real-time Reflection using Ray Tracing with Geometry Field
(The Eurographics Association, 2006) Li, Shengying; Fan, Zhe; Yin, Xiaotian; Mueller, Klaus; Kaufman, Arie E.; Gu, Xianfeng; Dieter Fellner and Charles Hansen
A novel method for accurate reflections in real time is introduced using ray tracing in geometry fields, which combine light fields with geometry images. The geometry field of a surface is defined ray space, mapping a ray to its intersection point with the surface, represented as the uv coordinates on the geometry image. It makes intersection tests much more efficient using lookups within a fragment shader, and allows conventional textures to be applied, such as normal maps, to enhance geometric subtleties. Our method can be generalized to also handle refraction and self-reflection. Experimental results demonstrate its capability for accurate reflection for complex scenes in real-time.
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.

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