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Item Octreemizer: A Hierarchical Approach for Interactive Roaming Through Very Large Volumes(The Eurographics Association, 2002) Plate, John; Tirtasana, Michael; Carmona, Rhadamés; Fröhlich, Bernd; D. Ebert and P. Brunet and I. NavazoWe have developed a hierarchical paging scheme for handling very large volumetric data sets at interactive frame rates. Our system trades texture resolution for speed and uses effective prediction strategies. We have tested our approach for datasets with up to 16GB in size and show that it works well with less than 500MB of main memory cache for 64MB of 3D-texture memory. Our approach makes it feasible to deal with these volumes on desktop machines.Item Resample Hardware for 3D Graphics(The Eurographics Association, 2002) Meinds, Koen; Barenbrug, Bart; Thomas Ertl and Wolfgang Heidrich and Michael DoggettTexture mapping is a core technology of current real-time 3D graphics systems. To avoid aliasing artifacts, the texture mapping resample process requires proper filtering. We present a new resample algorithm for twopass forward texture mapping that is suited to an efficient hardware implementation. This method delivers high quality anti-aliased images using filter techniques based on digital signal processing. We use an input sample driven texture resample and filtering algorithm that "splats" the contribution of each input sample (texel) to output samples (pixels). We show how the algorithm can be efficiently implemented in a hardware resample structure. The algorithm is incorporated and tested in a standard 3D graphics pipeline using the OpenGL interface. Our results exhibit better anti-aliasing of textures than anisotropic filtering found in current advanced graphics chips. We also show that the same texture filtering method can be used to implement edge anti-aliasing. Our edge anti-aliasing results show an absence of aliasing on most edges.Item Interactive High-Quality Volume Rendering with Flexible Consumer Graphics Hardware(Eurographics Association, 2002) Engel, Klaus; Ertl, ThomasRecently, the classic rendering pipeline in 3D graphics hardware has become flexible by means of programmable geometry engines and rasterization units. This development is primarily driven by the mass market of computer games and entertainment software, whose demand for new special effects and more realistic 3D environments induced a reconsideration of the once static rendering pipeline. Besides the impact on visual scene complexity in computer games, these advances in flexibility provide an enormous potential for new volume rendering algorithms. Thereby, they make yet unseen quality as well as improved performance for scientific visualization possible and allow to visualize hidden features contained within volumetric data. The goal of this report is to deliver insight into the new possibilities that programmable state-of-the-art graphics hardware offers to the field of interactive, high-quality volume rendering. We cover different slicing approaches for texture-based volume rendering, non-polygonal iso-surfaces, dot-product shading, environment-map shading, shadows, pre- and post-classification, multi-dimensional classification, high-quality filtering, pre-integrated classification and pre-integrated volume rendering, large volume visualization and volumetric effects.Item The 3D Model Acquisition Pipeline(Blackwell Publishers Ltd and the Eurographics Association, 2002) Bernardini, Fausto; Rushmeier, HollyThree-dimensional (3D) image acquisition systems are rapidly becoming more affordable, especially systems based on commodity electronic cameras. At the same time, personal computers with graphics hardware capable of displaying complex 3D models are also becoming inexpensive enough to be available to a large population. As a result, there is potentially an opportunity to consider new virtual reality applications as diverse as cultural heritage and retail sales that will allow people to view realistic 3D objects on home computers.Although there are many physical techniques for acquiring 3D data-including laser scanners, structured light and time-of-flight-there is a basic pipeline of operations for taking the acquired data and producing a usable numerical model. We look at the fundamental problems of range image registration, line-of-sight errors, mesh integration, surface detail and color, and texture mapping. In the area of registration we consider both the problems of finding an initial global alignment using manual and automatic means, and refining this alignment with variations of the Iterative Closest Point methods. To account for scanner line-of-sight errors we compare several averaging approaches. In the area of mesh integration, that is finding a single mesh joining the data from all scans, we compare various methods for computing interpolating and approximating surfaces. We then look at various ways in which surface properties such as color (more properly, spectral reflectance) can be extracted from acquired imagery. Finally, we examine techniques for producing a final model representation that can be efficiently rendered using graphics hardware.Item 3D Data Acquisition(Eurographics Association, 2002) Scopigno,Roberto; Andujar, Carlos; Goesele,Michael; Lensch, Hendrik P. A.3D scanners and image acquisition systems are rapidly becoming more affordable and allow to build highly accurate models of real 3D objects in a cost- and time-effective manner. This tutorial will present the potential of this technology, review the state of the art in model acquisition methods, and will discuss the 3D acquisition pipeline from physical acquisition until the final digital model. First, different scanning techniques such as time-of-flight or structured light approaches will briefly be presented. Other acquisition related issues including the design of the scanning studio will be discussed and evaluated. In the area of registration, we will consider both the problems of initially aligning individual scans, and of refining this alignment with variations of the Iterative Closest Point method. For scan integration and mesh reconstruction, we will compare various methods for computing interpolating and approximating surfaces. We will then look at various ways in which surface properties such as color and reflectance can be extracted from acquired imagery. Finally, we will examine techniques for the efficient management and rendering of very large, attribute-rich meshes, including methods for the construction of simplified triangle-based representation and sample-based rendering approaches.Item Hardware-Accelerated Point-Based Rendering of Complex Scenes(The Eurographics Association, 2002) Coconu, Liviu; Hege, Hans-Christian; P. Debevec and S. GibsonHigh quality point rendering methods have been developed in the last years. A common drawback of these approaches is the lack of hardware support. We propose a novel point rendering technique that yields good image quality while fully making use of hardware acceleration. Previous research revealed various advantages and drawbacks of point rendering over traditional rendering. Thus, a guideline in our algorithm design has been to allow both primitive types simultaneously and dynamically choose the best suited for rendering. An octree-based spatial representation, containing both triangles and sampled points, is used for level-of-detail and visibility calculations. Points in each block are stored in a generalized layered depth image. McMillan s algorithm is extended and hierarchically applied in the octree to warp overlapping Gaussian fuzzy splats in occlusion-compatible order and hence z-buffer tests are avoided. We show how to use off-the-shelf hardware to draw elliptical Gaussian splats oriented according to normals and to perform texture filtering. The result is a hybrid polygon-point system with increased efficiency compared to previous approaches.Item Efficient High Quality Rendering of Point Sampled Geometry(The Eurographics Association, 2002) Botsch, Mario; Wiratanaya, Andreas; Kobbelt, Leif; P. Debevec and S. GibsonWe propose a highly efficient hierarchical representation for point sampled geometry that automatically balances sampling density and point coordinate quantization. The representation is very compact with a memory consumption of far less than 2 bits per point position which does not depend on the quantization precision. We present an efficient rendering algorithm that exploits the hierarchical structure of the representation to perform fast 3D transformations and shading. The algorithm is extended to surface splatting which yields high quality anti-aliased and water tight surface renderings. Our pure software implementation renders up to 14 million Phong shaded and textured samples per second and about 4 million anti-aliased surface splats on a commodity PC. This is more than a factor 10 times faster than previous algorithms.Item pgv02(2002)Item Avatar Markup Language(The Eurographics Association, 2002) Kshirsagar, Sumedha; Magnenat-Thalmann, Nadia; Guye-Vuillème, Anthony; Thalmann, Daniel; Kamyab, Kaveh; Mamdani, Ebrahim; S. Mueller and W. StuerzlingerSynchronization of speech, facial expressions and body gestures is one of the most critical problems in realistic avatar animation in virtual environments. In this paper, we address this problem by proposing a new high-level animation language to describe avatar animation. The Avatar Markup Language (AML), based on XML, encapsulates the Text to Speech, Facial Animation and Body Animation in a unified manner with appropriate synchronization. We use low-level animation parameters, defined by the MPEG-4 standard, to demonstrate the use of the AML. However, the AML itself is independent of any low-level parameters as such. AML can be effectively used by intelligent software agents to control their 3D graphical representations in the virtual environments. With the help of the associated tools, AML also facilitates to create and share 3D avatar animations quickly and easily. We also discuss how the language has been developed and used within the SoNG project framework. The tools developed to use AML in a real-time animation system incorporating intelligent agents and 3D avatars are also discussed subsequently.Item Artistic Surface Rendering Using Layout of Text(Blackwell Publishers Ltd and the Eurographics Association, 2002) Surazhsky, Tatiana; Elber, GershonAn artistic rendering method of free-form surfaces with the aid of half-toned text that is laid-out on the given surface is presented. The layout of the text is computed using symbolic composition of the free-form parametric surface S(u, v) with cubic or linear Bezier curve segments C(t) = cu (t), cv (t), comprising the outline of the text symbols. Once the layout is constructed on the surface, a shading process is applied to the text, affecting the width of the symbols as well as their color, according to some shader function. The shader function depends on the surface orientation and the view direction as well as the color and the direction or position of the light source.