EG2003

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https://diglib7.eg.org/handle/10.2312/234

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3D Model Search Engine Based on Lightfield Descriptors
(Eurographics Association, 2003) Shen, Yu-Te; Chen, Ding-Yun; Tian, Xiao-Pei; Ouhyoung, Ming
With the development of modern 3D modelling and digitizing tools, more and more models have been created recently, which leads to the necessity of the technique of 3D model retrieval system. Our 3D model search engine has been designed with the goal to meet entertaining, industrial, commercial, medical, and educational needs. The system is available on the Web (http://3d.csie.ntu.edu.tw) with a database containing over 10,000 models free downloaded through the Internet. Users can query 3D models by text, drawing 2D shapes using a friendly painting interface, or selecting one 3D model as a query key interactively. The features representing a 3D object, namely, the Lightfield Descriptors, are extracted from 2D images, which are rendered from cameras positioned on the vertices of a regular dodecahedron. The Lightfield Descriptors of each model are used to compare similarities among each other, and the retrieval process takes only 2 and 0.1 seconds with a 3D model and 2D shapes, respectively. During four months, the system has been widely used for querying over three thousand times from 418 IP addresses in at least 27 countries.
3deSoundBox – a Scalable, Platform-Independent 3D Sound System for Virtual and Augmented Reality Applications
(Eurographics Association, 2003) Stampfl, Philipp
Sound is one of the most important components in animations, presentations and especially immersive environments. Many aspects are recognized more intuitively when sound supports vision and it is easier to follow a story and to believe in a virtual world of illusion. The 3deSoundBox was designed to provide this important acoustic component for such kind of 3D applications in an easy and intuitive way. It is scalable, platform-independent, has an easy to use interface and offers a lot of new possibilities in the field of virtual and augmented reality applications. The 3deSoundBox system can drive any number of speakers and works with any application on any platform with the same range of service. Once programmed, an application can easily take advantage of these features, as it will work on any sound-system with any number of speakers without requiring any changes, due to the scalable architecture of the system.
Accurate Dense Stereo Reconstruction using Graphics Hardware
(Konrad, 2003) Zach, Christopher; Klaus, Andreas; Hadwiger, Markus; Karner, Konrad
Vertex programs and pixel shaders found in modern graphics hardware are commonly used to enhance the realism of rendered scenes. Recently these hardware facilities were exploited to obtain interactive non-photorealistic effects and to perform low-level image processing tasks like texture filtering for volume visualization. We exploit modern graphics hardware to accomplish the higher level vision task of dense stereo reconstruction. In our system almost every stage of the matching procedure is executed on 3D graphics hardware, therefore utilizing the parallel vertex and pixel pipelines. Our implementation performs accurate calculations and does not suffer from the limited precision of color channels. On state of the art PC hardware our algorithm requires less than one second to reconstruct a dense mesh with subpixel accuracy for input images with one megapixel resolution.
ActiveInk
(Eurographics Association, 2003) Tobita, Hiroaki; Rekimoto, Jun
The ActiveInk system integrates the advantages of real world painting techniques with computer graphics (CG) effects such as natural phenomenon animations (e.g., water, fire, snow, and clouds), attributes (e.g., rubber, cloth, and land), surface materials (e.g., texture effects, metal, and glass), and so on. Most conventional paint systems mainly allow users to set a simple and static color. Also, they require users to control many parameters if the user applies complex effects. However, the ActiveInk system treats many behaviors as separate behavior inks (e.g., water, cloud, and cloth ink), so a user can add effects by selecting a behavior ink and painting it onto objects to realize CG effects. Moreover, the system has a palette area that is similar in function to an actual painters palette, so the user can create a new ink by mixing different types of behavior ink and can control the behavior in the palette area directly. In this paper, we describe a prototype of the ActiveInk system, explain how it allows CG effects to be applied through simple and easy manipulations, and discuss its implementation.
Adaptive quantization with error bounds for compressed view-dependent multiresolution meshes
(Eurographics Association, 2003) Grabner, Markus; Zach, Christopher
We present a simple method to adaptively determine compression parameters according to the given input data. Our method allows to make better use of the available dynamic range (number of bits per component of vertex locations) than with a given fixed-point representation. Moreover, the number of bits per component is also determined adaptively under a user-specified upper bound for the quantization error. Our adaptive quantization method can handle models with largely non-uniform geometric resolution. This is typically the case for manually created models or models derived from different sensors. The experiments we performed demonstrate the benefits of the proposed method.
Advanced Shading Techniques
(Eurographics Association, 2003) Diepstraten, Joachim
Focus of this talk: • Per-pixel point light Blinn-Phong lighting • Per-pixel realistic metal-BRDF • Per-pixel anisotropic lighting • Procedural textures • Different reflection/environment mapping techniques • “Faked“ translucency
Alternative Augmented Reality Approaches: Concepts, Techniques, and Applications
(Eurographics Association, 2003) Bimber, Oliver; Raskar, Ramesh
In this tutorial we discuss application specific alternative augmented reality (AR) approaches –such as Virtual Showcases and Shader Lamps– that focus on overcoming some of the limitations linked to conventional AR displays. State-of-the-art concepts, details about hard- and software implementations, and current areas of application are presented. An extensive overview over different stereoscopic and auto-stereoscopic display techniques is given. This enables readers to identify parallels between Virtual Reality and augmented reality displays concepts, and stimulate them to think about alternative approaches for AR. Our focus is on interactive rendering techniques that support display concepts, such as projector-based or spatial optical seethrough AR. Methods that create graphical augmentations with respect to the applied optical elements and display surfaces, and techniques for creating a high level of consistency between real and virtual environments will be discussed. Finally, our experiences made with such technologies within art, edutainment, research and industrial areas will be shared with the audience. By handing out construction drawings and algorithms, we aim at enabling participants to realize such systems on their own.
Animating Tree Movement with Sound Effects Generation
(Eurographics Association, 2003) Matsuyama, Katsutsugu; Ota, Shin; Tamura, Machiko; Fujimoto, Tadahiro; Muraoka, Kazunobu; Chiba, Norishige
This video demonstrates the methods for automatically generating tree motions and sound effects for an animation of branches and leaves moving in the wind. Natural motions of leaves and branches swaying in a wind field are created in real-time by our efficient method without using time-consuming physical simulation techniques based on the equations of motion. This method utilizes "1/f ? noise", which is observed in various natural phenomena. Specifically, in this method, the natural motions of leaves and branches are created by calculating appropriate motion angles using 1/f ? noise functions. The realism of the branch motion is enhanced by applying a real-time simple simulation technique based on the spring model. Sound effects are generated as follows: Each tree is divided into branches and leaves, and an independent sound effect generation process is employed for each element. The individual results are then compounded into one sound effect. For the branches, we employ an approach based on the frequencies of experimentally obtained Karman vortex streets. For the leaves, we use the leaf blade state as the input and assume a virtual musical instrument that uses wave tables as the sound source. All computations can be performed independently for each frame step.
Animatope: A Manga-Styled Animation Expression Toolkit
(Eurographics Association, 2003) Tohda, Asuka; Hasegawa, Sho; Inakage, Masa
Manga, a Japanese comic style, is becoming widely accepted within comic readers worldwide. In Manga, mimetic symbols and onomatopoeia symbols are heavily used to express emotions and various movements in a comic frame. In this paper, we present a toolkit named "Animatope", to emulate Manga-style symbols in a non-photorealisitc animation. Animatope transfers the Manga-sytle symbol grammar to 3D animation. We extend Manga symbols to Meta-symbols, or animated symbols, to enrich the emotional expressions and subtle behaviors. Meta-symbols are categorized into several classifications in Animatope Toolkit. Meta-symbols are controlled with basic parameters, shape of emitters, and motion handles.
Anisotropic Participating Media at Near Interactive Rates
(Eurographics Association, 2003) Jimenez, Juan-Roberto; Pueyo, Xavier
This article presents an algorithm for the realistic simulation, at near interactive rates, of globally illuminated scenes including participating media, isotropic and anisotropic. The proposed algorithm is divided in three phases: particle tracing, reconstruction and rendering. The particle tracing phase is based on the Monte Carlo light tracing. The goal of this phase is to deliver the light energy from the sources, over the scene’s object. In the reconstruction phase the algorithm derives one texture for each object in the scene, 2D textures for surfaces and 3D textures for participating media. Each texel represents the outgoing radiance, in a given direction, from a region of the object. The method uses density estimation techniques to compute the textures. In the final phase, the algorithm renders the textures using hardware graphics capabilities.
Ashli – Advanced Shading Language Interface
(Eurographics Association, 2003) Preetham, Arcot J.; Bleiweiss, Avi
The support for IEEE floating point computation and the exposure of shading functionality in a standardize API form have made graphics hardware a viable workflow solution to an artist involved in digital content creation (DCC). Nevertheless, there still remains a significant interface void between the abstract shading description an artist is used to and the low level shading constructs the hardware expec ts. We have developed Ashli, an advanced shading language interface tool, with the primary motivation to bridge the interface gap fore mentioned. Ashli is developed in the form of a case study. It takes in high level shading languages and descriptions and at the end emits standard graphics hardware shading API (e.g. Microsoft DirectX and OpenGL). Ashli‘s main contribution is in its seamless cooperation with the DCC graphics application. The RenderMan®‡ Shading Language, Maya® Shading Network and 3ds Max® Standard Materials are the subset of input abstraction we have experimented with to validate our approach. Shading path computation complexity and conformance to hardware resource constraints are owned by Ashli and for the most part made transparent to the artist. A tool like Ashli essentially retains rendered image appearance quality comparable to the level produced by a software renderer, but at a significant higher rate of interaction efficiency. We present Ashli in the context of a stand -alone viewing application framework, depicting shading path computation bound to scene rendering. We demonstrate the application design and results for using Ashli as a shading coprocessor assist.
Automatic High Level Avatar Guidance Based on Affordance of Movement
(Eurographics Association, 2003) Michael, Despina; Chrysanthou, Yiorgos
As virtual cities become ever more common and more extensive, the need to populate them with virtual pedestrians grows. One of the problems to be resolved for the virtual population is the behaviour simulation. Currently specifying the behaviour requires a lot of laborious work. In this paper we propose a method for automatically deriving the high level behaviour of the avatars. We introduce to the Graphics community a new method adapted from ideas recently presented in the Architecture literature. In this method, the general avatar movements are derived from an analysis of the structure of the architectural model. The analysis tries to encode Gibsons 7 principle of affordance, interpreted here as: pedestrians are more attracted towards directions with greater available walkable surface. We have implemented and tested the idea in a 2x2 km2 model of the city of Nicosia. Initial results indicate that the method, although simple, can automatically and efficiently populate the model with realistic results.
Beyond Image Quality Comparison
(Eurographics Association, 2003) Bornik, Alexander; Cech, Peter; Ferko, Andrej; Perko, Roland
We solve the problem of quantitative measuring of image quality, beyond the widely used MSE (mean square error) or even visual comparison. We combine eight feature-based and perceptually-oriented image quality metrics. The need for this comes from virtual archaeology, where various image acquisitions, antialiasing, multiresolution, image reconstruction or texturing methods produce very similar images. The proposed evaluation framework is suitable for any image quality decision-making, being not restricted to virtual archaeology. In particular, we compare a representative database of visually indistiguishable image pairs from different cameras, anisotropic texture filters and various antialiasing methods. For image registration we propose a modified video processing step. The results support the selection beyond commonly used visual comparison.
Building Large Area Multi-Projector Displays
(Eurographics Association, 2003) Brown, Michael S.; Majumder, Aditi
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Certosa virtual museum: a dynamic multilevel desktop VR application
(Eurographics Association, 2003) Calori, L.; Diamanti, T.; Guidazzoli, A.; Liguori, M. C.; Mauri, M. A.; Valentini, L.
Starting from the exigencies of restoration, safeguard and promotion set by Bologna City Council for its Museum of the Certosa Cemetery, a multilevel application has been developed. Its main features are dynamic generation of models, interaction with objects, link to relational multimedia database, DTM and a friendly, computer games like interface. The outcome is a flexible product, both from a technological point of view – it can be experienced on low cost platforms as well as in HI End systems - and for the possible kind of fruition, that can involve several different groups of users.
Combining 3D Scans and Motion Capture for Realistic Facial Animation
(Eurographics Association, 2003) Breidt, Martin; Wallraven, Christian; Cunningham, Douglas W.; Buelthoff, Heinrich H.
We present ongoing work on the development of new methods for highly realistic facial animation. One of the main contributions is the use of real-world, high-precision data for both the timing of the animation and the deformation of the face geometry. For animation, a set of morph shapes acquired through a 3D scanner is linearly morphed according to timing extracted from point tracking data recorded with an optical motion capture system.
Continuous Local Parameterization of Polygons
(Eurographics Association, 2003) Maillot, Jerome
Texture mapping has now become a standard technique for adding visual details to 3d models. Nevertheless, intuitive mapping tools have made little progress in the past decade, compared to other computer graphics areas: defining a good quality parameterization is still a tedious process, requiring experienced and skilled users. In this paper, we specifically address the problem of finding automatically a parameterization of a reasonably small portion of the surface. This method is simple and efficient, which makes it suitable for interactive applications. It is also continuous in terms of the user input, so that it is stable during animation and interaction. Finally, it only requires the user to define a small set of intuitive parameters, mostly position, size and orientation of the area to be parameterized. Thus, it can be used by inexperienced users and easily connected to existing applications. We show how our method can improve 3D-paint systems and decal placement on surfaces. The same approach can also be used to adapt 2D image processing tools to geometry filtering.
Crosstalk reduction in passive stereo-projection systems
(Eurographics Association, 2003) Klimenko, Stanislav; Frolov, Pavel; Nikitina, Lialia; Nikitin, Igor
We describe a scheme for reduction of depolarization artefacts in passive stereo-projection systems. These problems appear due to non-perfectness of stereo-projection equipment: depolarization of the light due to reflection from the screen or due to the passage through the screen, non-ideality of polarizing filters, mixing of left- and right-eye images in a change of relative orientation of the filters, which together produce a strong crosstalk effect, resulting to difficulting stereo-perception. The artefacts are eliminated by software methods, using linear filtering of the image before its projection to the screen. We have implemented this algorithm in VE system Avango 1 by means of texture mappings. All necessary operations are performed by the graphics board, thus providing the real-time rendering rate. The described method considerably improves stability of stereo-perception, making high-quality performances of virtual environment possible on affordable equipment.
Curve Synthesis from Learned Refinement Models
(Eurographics Association, 2003) Simhon, Saul; Dudek, Gregory
We present a method for generating refined 2D illustrations from hand drawn outlines consisting of only curve strokes. The system controllably synthesizes novel illustrations by augmenting the hand drawn curves’ shape, thickness, color and surrounding texture. These refinements are learned from a training ensemble. Users can select several examples that depict the desired idealized look and train the system for that type of refinement. Further, given several types of refinements, our system automatically recognizes the curve and applies the appropriate refinement. Recognition is accomplished by evaluating the likelihood the curve belongs to a particular class based on both its shape and context in the illustration.
Cyclification of Human Motion for Animation Synthesis
(Eurographics Association, 2003) Ahmed, Amr; Mokhtarian, Farzin; Hilton, Adrian
In this paper, new techniques are introduced for matching cyclic motion boundaries by using simple animation processing algorithms based on some observed characteristics from different families of cyclic motions. Matching the cycle boundaries is one of the essential stages in generating a stream of animation of cyclic human movements. If the cycle boundaries are not matched, noticeable artefacts and flickers will appear regardless of how realistic the available motion cycle is. The proposed techniques are developed to modify the motion cycle even in the case, where only one cycle is provided. These techniques do not only match the cycle boundaries but also correct other parts of the cycle and motion constraints. The techniques are computationally efficient as they work directly on the animation data (without conversion to intermediate representations such as spline or time-frequency transforms). Moreover, many aspects of animation (including joint limits and important motion constraints) are preserved as the modification is guided by the original motions. A simple framework for automatic detection of gait phases timing is also introduced.

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