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End date: 2009 × Subject: Picture/Image Generation × Has files: true ×

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Now showing 1 - 10 of 27
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    A Virtual Memory System Organization for Bit-Mapped Graphics Displays
    (The Eurographics Association, 1989) Barkans, Anthony C.; Richard Grimsdale and Wolfgang Strasser
    Described is a display sub-system, designed for support of a very high speed rendering engine. It provides high-performance graphics to an enVironment that consists of a hierarchy of resizable windows. The concept of virtual memory has been applied with the organization of the virtual to physical address spaces having a unique mapping that fits the organization of a bit-mapped graphics memory display.
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    Real-Time Bump Map Synthesis
    (The Eurographics Association, 2001) Kautz, Jan; Heidrich, Wolfgang; Seidel, Hans-Peter; Kurt Akeley and Ulrich Neumann
    In this paper we present a method that automatically synthesizes bump maps at arbitrary levels of detail in real-time. The only input data we require is a normal density function; the bump map is generated according to that function. It is also used to shade the generated bump map. The technique allows to infinitely zoom into the surface, because more (consistent) detail can be created on the fly. The shading of such a surface is consistent when displayed at different distances to the viewer (assuming that the surface structure is self-similar). The bump map generation and the shading algorithm can also be used separately.
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    Point-driven Generation of Images from a Hierarchical Data Structure
    (The Eurographics Association, 1988) Jong, Dirk de; Siobbe, Paul van; Splunter, Marinus van; A. A. M.Kuijk
    In this paper, a system IS described which renders an image from a hierarchical data structure in a point-driven way. The data structure allows dynamic color mapping and arbitrary affine transformat·ons of objects with respect to their parent coordinate system. The point driven method allows for easy VLSI implementation, efficient use oj memory and exploitation of parallelism.
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    Real-Time Capture, Reconstruction and Insertion into Virtual World of Human Actors
    (The Eurographics Association, 2003) Hasenfratz, J.M.; Lapierre, M.; Gascuel, J.-D.; Boyer, E.; Peter Hall and Philip Willis
    In this paper, we show how to capture an actor with no intrusive trackers and without any special environment like blue set, how to estimate its 3D-geometry and how to insert this geometry into a virtual world in real-time. We use several cameras in conjunction with background subtraction to produce silhouettes of the actor as observed from the different camera viewpoints. These silhouettes allow the 3D-geometry of the actor to be estimated by a voxel based method. This geometry is rendered with a marching cube algorithm and inserted into a virtual world. Shadows of the actor corresponding to virtual lights are then added and interactions with objects of the virtual world are proposed. The main originality of this paper is to propose a complete pipeline that can computes up to 30 frames per second. Since the rapidity of the process depends mainly on its slowest step, we present here all these steps. For each of them, we present and discuss the solution that is used. Some of them are new solutions, as the 3D shape estimation which is achieved using graphics hardware. Results are presented and discussed.
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    Memory Access Patterns of Occlusion-Compatible 3D Image Warping
    (The Eurographics Association, 1997) Murk, William R.; Bishop, Gary; A. Kaufmann and W. Strasser and S. Molnar and B.-O. Schneider
    McMillan and Bishop s 3D image warp can be efficiently implemented by exploiting the coherency of its memory accesses. We analyze this coherency, and present algorithms that take advantage of it. These algorithms traverse the reference image in an occlusion-compatible order, which is an order that can resolve visibility using a painter s algorithm. Required cache sizes are calculated for several one-pass 3D warp algorithms, and we develop a two-pass algorithm which requires a smaller cache size than any of the practical one-pass algorithms. We also show that reference image traversal orders that are occlusion-compatible for continuous images are not always occlusion-compatible when applied to the discrete images used in practice.
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    Z3: An Economical Hardware Technique for High-Quality Antialiasing and Transparency
    (The Eurographics Association, 1999) Jouppi, Norman P.; Chang, Chun-Fa; A. Kaufmann and W. Strasser and S. Molnar and B.- O. Schneider
    In this paper we present an algorithm for low-cost hardware antialiasing and transparency. This technique keeps a central Z value along with compact floating-point Z gradients in the X and Y dimensions for each fragment within a pixel (hence the name Z3). It uses a small fixed amount of storage per pixel. If the visible complexity of the pixel exceeds the storage space available for the pixel, the minimum number of fragments having the closest Z values are merged. This combines different fragments from the same surface, resulting in both storage and processing efficiency. When operating with opaque surfaces, Z3 can provide superior image quality over sparse supersampling methods that use eight samples per pixel while using storage for only three fragments. Z3 also makes the use of large numbers of samples (e.g., 16) feasible in inexpensive hardware, enabling higher quality images. It is simple to implement because it uses a small fixed number of fragments per pixel. Z3 can also provide order-independent transparency even if many transparent surfaces are present. Moreover, unlike the original A-buffer algorithm it correctly antialiases interpenetrating transparent surfaces because it has three-dimensional Z information within each pixel.
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    Regularised Anisotropic Nonlinear Diffusion for Rendering Refraction in Volume Graphics
    (The Eurographics Association, 2005) Rodgman, David; Chen, Min; Mike Chantler
    Rendering refraction in volume graphics requires smoothly distributed normals to synthesise good quality visual representations. Such refractive visualisation is more susceptible to noise in the data than visualisations that do not involve refraction. In this paper, we addresses the need for improving the continuity of voxel gradients in discretely sampled volume datasets using nonlinear diffusion methods, which was originally developed for image denoising. We consider the necessity for minimising unnecessary geometrical distortion, detail the functional specification of a volumetric filter for regularised anisotropic nonlinear diffusion (R-ANLD), discuss the further improvements of the filter, and compare the efficacy of the filter with an anisotropic nonlinear diffusion (ANLD) filter as well as a Gaussian filter and a linear diffusion filter. Our results indicate that it is possible to make significant improvements in image quality in refractive rendering without excessive distortion.
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    PixelFlow: The Realization
    (The Eurographics Association, 1997) Eyles, John; Molnar, Steven; Poulton, John; Greer, Trey; Lastra, Anselmo; England, Nick; Westover, Lee; A. Kaufmann and W. Strasser and S. Molnar and B.-O. Schneider
    PixelFlow is an architecture for high-speed, highly realistic image generation, based on the techniques of object-parallelism and image composition. Its initial architecture was described in [MOLN92]. After development by the original team of researchers at the University of North Carolina, and codevelopment with industry partners, Division Ltd. and Hewlett- Packard, PixelFlow now is a much more capable system than initially conceived and its hardware and software systems have evolved considerably. This paper describes the final realization of PixelFlow, along with hardware and software enhancements heretofore unpublished.
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    Interactive Rendering of Atmospheric Scattering Effects Using Graphics Hardware
    (The Eurographics Association, 2002) Dobashi, Yoshinori; Yamamoto, Tsuyoshi; Nishita, Tomoyuki; Thomas Ertl and Wolfgang Heidrich and Michael Doggett
    To create realistic images using computer graphics, an important element to consider is atmospheric scattering, that is, the phenomenon by which light is scattered by small particles in the air. This effect is the cause of the light beams produced by spotlights, shafts of light, foggy scenes, the bluish appearance of the earth s atmosphere, and so on. This paper proposes a fast method for rendering the atmospheric scattering effects based on actual physical phenomena. In the proposed method, look-up tables are prepared to store the intensities of the scattered light, and these are then used as textures. Realistic images are then created at interactive rates by making use of graphics hardware.
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    TRIANGLECASTER Extensions To 3BTexturing Units For Accelerated Volume Rendering
    (The Eurographics Association, 1999) Knittel, Gunter; A. Kaufmann and W. Strasser and S. Molnar and B.- O. Schneider
    We discuss hardware extensions to 3D-texturing units, which are very small but nevertheless remove some substantial performance limits typically found when using a 3D-texturing unit for volume rendering. The underlying algorithm uses only a slight modification of existing method, which limits negative impacts on application software. In particular, the method speeds up the compositing operation, improves texture cache eflciency and allows for early ray termination and empty space skipping. Early ray termination can not be used in the traditional approach. Simulations show that, depending on data set properties, the performance of readily available, low-cost PC graphics accelerators is already suflcient for real-time volume visualization. Thus, in terms ofperformance, the TRIANGLECASTER-extensions can make dedicated volume rendering accelerators unnecessary.