EG2003
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Item Curve Synthesis from Learned Refinement Models(Eurographics Association, 2003) Simhon, Saul; Dudek, GregoryWe 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.Item Efficient Sampling of Textured Scenes in Vertex Tracing(Eurographics Association, 2003) Ullmann, Thomas; Preidel, Thomas; Bruderlin, BeatWe present vertex tracing, an adaptive progressive ray tracing approach for efficient sampling of the radiance function, based on refinement in object space and subsequent reconstruction, using standard 3D graphics accelerator hardware. The main focus of this paper is the reconstruction of reflected and transmitted texture maps. By taking advantage of the newest graphics hardware features (such as the pixel shader) even higher levels of recursion can be supported without explicit sampling of the textures. In addition, the graphics hardware is used for an efficient visibility test, which leads to a further reduction of ray samples, and for the rendering of diffuse local illumination effects, as well as for progressive rendering of the global illumination effects, which are superimposed over the hardware-rendered scene in object space. With this approach, interactive performance for realistically rendered illumination effects of scenes of average complexity, can be achieved on a standard PC with off-the-shelf 3D graphics accelerators.Item Real-time Obscurances with Color Bleeding (the three cubes demo)(Eurographics Association, 2003) Méndez, Àlex; Sbert, Mateu; Catà, JordiHere we present an animation that demonstrates the power of the obscurances technique and how it can be used in a video-game context when moving objects are in the scene. Obscurances is a powerful technique that simulates diffuse illumination, i.e. radiosity, with a much lower cost. Its advantage is based in that it considers only neighbour interactions instead of considering global ones, and in being decoupled from direct illumination computation. The implementation of this technique is made on a 3D game engine that allows real-time recomputation of obscurances for moving objects. Extensions to deal with color bleeding can also be appreciated.Item Reconstruction of Animatable Personalized 3D Faces by Adaptation-based Modeling(Eurographics Association, 2003) Zhang, Yu; Sim, Terence; Tan, Chew LimWe present an efficient method for the construction of an animatable 3D facial model of a specific person with minimal user interaction. The method is based on adapting an anatomy-based prototype facial model that is suitable for physically-based facial animation to the geometry of a real persons face recovered from laser-scanned range data. Starting with specification of a set of anthropometric landmarks on the 2D images, we automatically recover the 3D positions of the landmark points on the facial surface. A global shape adaptation is then carried out to align the prototype model to the target geometry using the transformation parameters estimated from measurements between recovered 3D landmark points. A local shape adaptation follows to deform the prototype model for fitting all of its vertices to the scanned surface data. The reconstructed 3D face portrays the geometry and color of the individual face and can be animated immediately with the given muscle parameters.Item Occlusion Culling for Image-Based Rendering withWarping(Eurographics Association, 2003) Soner, I. Sen; Atalay, VolkanThe basic idea of the proposed algorithm is to reduce the number of depth pixels in Layer Depth Images (LDI) by culling the occluded ones before warping. The method combines the octree spatial subdivision concept with LDI concept, using the implicit geometry stored in depth pixels. The algorithm uses an octree to group depth pixels in a hierarchical way. The proposed algorithm is very effective when used in highly occluded scenes, and the density of the depth pixels should be high enough to get a high performance from the algorithmItem Freeform Shape Representations for Efficient Geometry Processing(Eurographics Association, 2003) Kobbelt, LeifThe most important concepts for the handling and storage of freeform shapes in geometry processing applications are parametric representations and volumetric representations. Both have their specific advantages and drawbacks. While the algebraic complexity of volumetric representations is independent from the shape complexity, the domain of a parametric representation usually has to have the same structure as the surface itself (which sometimes makes it necessary to update the domain when the surface is modified). On the other hand, the topology of a parametrically defined surface can be controlled explicitly while in a volumetric representation, the surface topology can change accidentally during deformation. A volumetric representation reduces distance queries or inside/outside tests to mere function evaluations but the geodesic neighborhood relation between surface points is difficult to resolve. As a consequence, it seems promising to combine parametric and volumetric representations to effectively exploit both advantages. In this talk, a number of projects are presented and discussed in which such a combination leads to efficient and numerically stable algorithms for the solution of various geometry processing tasks. Applications include global error control for mesh decimation and smoothing, topology control for level-set surfaces, and shape modeling with unstructured point clouds.Item A Refereed Server for Educational CG Content(Eurographics Association, 2003) Figueiredo, Frederico C.; Eber, Dena E.; Jorge, Joaquim A.Computer graphics has evolved considerably over the past few decades. As computer science, digital arts, and other areas of study that use computer graphics continue to evolve and gain new substance, educators have come to master new content and achieve deeper understandings of computers and imagery. As the core field becomes more mature, educators in all computer graphics disciplines have a greater need for high-quality curricular resources. Offering excellent educational materials is an important service to the community of educators. Such support will empower both young and seasoned educators alike to benefit from and contribute to the work of others. In this way, we can achieve a higher standard of teaching worldwide. The purpose of our work is to provide tools to foster such a community of computer graphics educators. We will present a system that will act as the means for their work to be appraised, assessed and made available to others through an online server for refereed educational content in computer graphics. In this paper we describe the basis for and highlight some of the starting requirements of CGEMS, the online Computer Graphics Educational Materials Server. This is organized around a web-based groupware application that supports the submission, review, acquisition, and archiving of curricular resources.Item Trans-Polygon Stroke Method for Frame Coherent Pastel Images(Eurographics Association, 2003) Murakami, Kyoko; Tsuruno, ReijiWe propose Trans-Polygon Stroke Method (TPSM) for creating pastel-like animation that keeps frame-to-frame coherence. There are several variable factors in hand-drawn pastel such as paper roughness and pigments. When these factors are simulated in computer graphics animation, they cause flickers, which reduces visibility. To increase the visibility of pastel-like animation by reducing the flickers, it is need to fix the factors. The procedure of the TPSM is to (1) model objects with quadrilateral polygons, (2) generate particles on the polygons, (3) give a vector direction to each particle, and (4) draw a line from the particle to the n-th polygon along with the direction. Besides the TPSM, the amount of pigments used for one stroke is read from a given table to fix this variable factor. We demonstrate several types of drawn strokes, such as hatching, stipple, and blending, using the proposed method.Item Particle-based Collision Detection(Eurographics Association, 2003) Senin, Mikhail; Nikita, Kojekine; Savchenko, Vladimir; Hagiwara, IchiroIn the paper we present a novel algorithm for collision detection between complex geometric objects represented by polygonal models and undergoing rigid motions and deformations. Most algorithms described in the literature deal with rigid bodies and are based on some kind of hierarchical representations. We present the alternative approach. The algorithm relies on the idea of "sensor particles": interacting particles distributed on a surface. Two types of particles that interact in a special way are used for determining the minimum distance between two models. The algorithm has been implemented and used in real time simulation of dynamic interaction between geometric objects. A detailed description of the algorithm, animation examples, and benchmarks are included in the paper. A potential application of this software algorithm is collision detection for animation of bodies with deformable surfaces.Item ActiveInk(Eurographics Association, 2003) Tobita, Hiroaki; Rekimoto, JunThe 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.Item Virtual Endoscopy in Research and Clinical Practice(Eurographics Association, 2003) Bartz, DirkVirtual endoscopy is among the most active topics in virtual medicine and medical imaging. It focuses on the virtual representation of minimally invasive procedures for training, planning, and diagnosis without an actual invasive intervention. In the past few years, virtual endoscopy modes have been transferred from research systems in virtually every commercial medical imaging software, but with a varying quality and flexibility. This report covers concepts used in current systems in research and products, and how they might be applied to daily practice in health-care. Specifically, I will start with an introduction into virtual endoscopy and the related medical field. This will also include typical scenarios of virtual endoscopy applications as they appear in clinical practice. This part will be followed by a discussion of the technical issues of virtual endoscopy and how are addressed in currently available systems. Among these issues are navigation through the respective body organ and the orientation aids for the users. Furthermore, I will highlight the different rendering techniques used and its impact on render speed and quality.Item Beyond Image Quality Comparison(Eurographics Association, 2003) Bornik, Alexander; Cech, Peter; Ferko, Andrej; Perko, RolandWe 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.Item Precise Deformation of Rheology MSD Model Calibrated by Randomized Algorithm(Eurographics Association, 2003) Noborio, Hiroshi; Nogami, Ryo; Enoki, RyoIn this paper, we propose and compare three kinds of mass-spring-damper (MSD) models of rheology object, and experimentally select the best model concerning to shape deformation and volume accuracy. The MSD model requires a few costs to calculate force propagation and shape deformation of rheology object. For this reason, the dynamic animation can be made by a personal computer within the video-frame rate (about twenty milli-seconds). Moreover, in order to maintain deformation precision, we calibrate all coefficients of dampers and springs under many experimental data by the randomized algorithm. Then in the set of simple pushing experimental operations, shape deformation and volume of virtual rheology object based on the best model is similar to these of real rheology object. This is a case study to generate dynamic animation efficiently and precisely by the MSD model.Item Preface(Eurographics Association, 2003)Item Multi-resolution modelling of terrains by using non restricted quadtree triangulation(Eurographics Association, 2003) Aguilera, A.; Torres, J. C.; Feito, F.The interactive visualization of terrains requires the processing of a high amount of data in real time, usually it is not possible to work with all of them on main in memory. In this work we present, a method which solves the above problem by means of using spatial indices (quadtree). For that, the terrains are divided into square cells, each of them having a quadtree, which will only be refined up to a the detail level depending on the observer position. With this, allaus to reduce the time used for terrains visualization.Item Shadow Mapping Based on Dual Depth Layers(Eurographics Association, 2003) Weiskopf, Daniel; Ertl, ThomasShadow maps are a widely used means for the generation of shadows although they exhibit aliasing artifacts and problems of numerical precision. In this paper we extend the concept of a single shadow map by introducing dual shadow maps, which are based on the two depth layers that are closest to the light source. Our shadow algorithm takes into account these two depth values and computes an adaptive depth bias to achieve a robust determination of shadowed regions. Dual depth mapping only modifies the construction of the shadow map and can therefore be combined with other extensions such as filtering, perspective shadow maps, or adaptive shadow maps. Our approach can be mapped to graphics hardware for interactive applications and can also be used in high-quality software renderers.Item Fast Marching farthest point sampling(Eurographics Association, 2003) Moenning, Carsten; Dodgson, Neil A.We introduce the Fast Marching farthest point sampling (FastFPS) approach for the progressive sampling of planar domains and curved manifolds in triangulated, point cloud or implicit form. By using Fast Marching methods2, 3, 6 for the incremental computation of distance maps across the sampling domain, we obtain a farthest point sampling technique superior to earlier point sampling principles in two important respects. Firstly, our method performs equally well in both the uniform and the adaptive case. Secondly, the algorithm is applicable to both images and higher dimensional surfaces in triangulated, point cloud or implicit form. This paper presents the methods underlying the algorithm and gives examples for the processing of images and triangulated surfaces. A companion report4 provides details regarding the application of the FastFPS algorithm to point clouds and implicit surfaces.Item Parametric Foveation for Progressive Texture and Model Transmission(Eurographics Association, 2003) Cheng, Irene; Basu, Anup; Pan, YixinSpatially varying sensing (foveation) has been used in many different areas of Computer Vision, such as image compression and video teleconferencing and in perceptually driven Level of Detail (LOD) representations in graphics. In this work, we show that foveation is advantageous for interactive mesh and texture transmission in online 3D applications. Unlike traditional mesh representations where all 3D vertices need to be transmitted, we only need to transmit a collection of points-of-interest (foveae) and information on only one (rather than three) axis. Thereby, we can achieve a threefold reduction in the amount of data that needs to be transmitted to represent a new 3D model. Our research differs from level of detail (LOD) based approaches using perceptually driven simplification in that (i) the mesh and texture resolutions vary smoothly and continuously in our approach compared to distinct levels of details in adjoining regions in other foveated or multiresolution LOD based methods; and (ii) the approach works for an integrated foveated texture and mesh representation. The current implementation extends our past research in image and video compression [1] and is restricted to regular grid mesh representation produced by 3D scanners.Item Non-Photorealistic Rendering(Eurographics Association, 2003) Eißele, Mike• Focus of this talk – Silhouette rendering – Cartoon shading – Hatching – Charcoal rendering – Image-space filter operations – Dither screensItem An Iterative Stripification Algorithm Based on Dual Graph Operations(Eurographics Association, 2003) Porcu, Massimiliano B.; Scateni, RiccardoThis paper describes the preliminary results obtained using an iterative method for generating a set of triangle strips from a mesh of triangles. The algorithm uses a simple topological operation on the dual graph of the mesh, to generate an initial stripification and iteratively rearrange and decrease the number of strips. Our method is a major improvement of a proposed one originally devised for both static and continuous level-of-detail (CLOD) meshes and retains this feature. The usage of a dynamical identification strategy for the strips allows us to drastically reduce the length of the searching paths in the graph needed for the rearrangement and produce loop-free triangle strips without any further controls and post-processing.