Volume 18 (1999)

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Browsing Volume 18 (1999) by Title

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    Active Storytelling
    (Blackwell Publishers Ltd and the Eurographics Association, 1999) Glassner, Andrew
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    Adaptable Splatting for Irregular Volume Rendering
    (Blackwell Publishers Ltd and the Eurographics Association, 1999) Wang, Wencheng; Wu, Enhua
    By employment of a footprint table in conducting intensity integration, splatting method has been very successful in rendering regular data volumes. Recently, the method has also been extended to render irregular data volumes. However, since samples in irregular volumes vary greatly in size and shape, the footprint table is unable to be employed in an efficient manner. This hinders the application of splatting approach from being used in the irregular volume case. In this paper, an adaptable splatting method is proposed, which provides an efficient way to integrate color intensity in terms of footprint table for the samples in various sizes. Experiments show that the new method may be used to produce better images without extra expense.
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    Adaptive Acquisition of Lumigraphs from Synthetic Scenes
    (Blackwell Publishers Ltd and the Eurographics Association, 1999) Schirmacher, Hartmut; Heidrich, Wolfgang; Seidel, Hans-Peter
    Light fields and Lumigraphs are capable of rendering scenes of arbitrary geometrical or illumination complexity in real time. They are thus interesting ways of interacting with both recorded real-world and high-quality synthetic scenes.Unfortunately, both light fields and Lumigraph rely on a dense sampling of the illumination to provide a good rendering quality. This induces high costs both in terms of storage requirements and computational resources for the image acquisition. Techniques for acquiring adaptive light field and Lumigraph representations are thus mandatory for practical applications.In this paper we present a method for the adaptive acquisition of images for Lumigraphs from synthetic scenes. Using image warping to predict the potential improvement in image quality when adding a certain view, we decide which new views of the scene should be rendered and added to the light field. This a-priori error estimator accounts for both visibility problems and illumination effects such as specular highlights.
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    An Adaptive Method for Area Light Sources and Daylight in Ray Tracing
    (Blackwell Publishers Ltd and the Eurographics Association, 1999) Zaninetti, Jacques; Boy, Pierre; Peroche, Bernard
    This paper proposes an adaptive method for taking both (diffuse or not) planar area light sources and daylight into account in a ray tracing environment which separates the calculation of direct and indirect illumination. In a given point, direct illumination due to a light source or to natural light is represented by a vector, the direction and magnitude of which being computed through an adaptive area approach, which is driven by the solid angle according to which a part of the source is seen from the current point. In the case of unoccluded diffuse polygonal sources, an analytical formula is used which gives an exact value for this vector.
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    Animating Sand, Mud, and Snow
    (Blackwell Publishers Ltd and the Eurographics Association, 1999) Sumner, Robert W.; Oâ Brien, James F.; Hodgins, Jessica K.
    Computer animations often lack the subtle environmental changes that should occur due to the actions of the characters. Squealing car tires usually leave no skid marks, airplanes rarely leave jet trails in the sky, and most runners leave no footprints. In this paper, we describe a simulation model of ground surfaces that can be deformed by the impact of rigid body models of animated characters. To demonstrate the algorithms, we show footprints made by a runner in sand, mud, and snow as well as bicycle tire tracks, a bicycle crash, and a falling runner. The shapes of the footprints in the three surfaces are quite different, but the effects were controlled through only five essentially independent parameters. To assess the realism of the resulting motion, we compare the simulated footprints to human footprints in sand.
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    Announcements
    (Blackwell Publishers Ltd and the Eurographics Association, 1999)
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    Announcements
    (Blackwell Publishers Ltd and the Eurographics Association, 1999)
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    Approximate Line Scan-Conversion and Antialiasing
    (Blackwell Publishers Ltd and the Eurographics Association, 1999) Chen, Jim X.; Wang, Xusheng
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    Book Reviews
    (Blackwell Publishers Ltd and the Eurographics Association, 1999)
    Books reviewed:Arlov, Laura. GUI Design for DummiesLeopoldseder, Hannes and Schopf, Christine (Editors). Cyberarts98Lorentz, H. A. On the Theory of the Reflection and Refraction of LightVince, John. Essential Virtual Reality FastJolion, J.-M. and Kropatsch, W. G. Graph-Based Representations in Pattern RecognitionKokaram, Anil C. Motion Picture Restoration: Digital Algorithms for Artefact Suppression in Degraded Motion Picture Film and Video
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    Book Reviews
    (Blackwell Publishers Ltd and the Eurographics Association, 1999)
    Books reviewed:Maeda, John. Design by NumbersKnuth, Donald E. Digital TypographyFarin, G., Bieri, H., Brunnet, G. and Derose, T. (Editors). Geometric ModellingKnudson, Jonathan. Java 2D GraphicsHege, H.-C. and Polthier, K. (Editors). Mathematical VisualizationPickover, Clifford (Editor). Chaos and Fractals: A Computer Graphical JourneyFlake, Gary William. The Computational Beauty of Nature: Computer Explorations of Fractals, Chaos, Complex Systems and AdaptationStrothotte, Thomas. Computational Visualization, Graphics, Abstraction and InteractivityRuss, John C. The Image Processing Handbook (3rd edition)
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    Calendar of Events
    (Blackwell Publishers Ltd and the Eurographics Association, 1999)
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    Capturing and Re-Using Rendition Styles for Non-Photorealistic Rendering
    (Blackwell Publishers Ltd and the Eurographics Association, 1999) Hamel, J.; Strothotte, T.
    Rendering high-quality non-photorealistic images of a given geometric model is often associated with a considerable amount of effort on the part of a user to fine-tune the rendition. In this paper we introduce a method and tools for re-using the user's effort invested in one model for the rendering of other models.Our method uses templates to describe rendition styles. The paper gives a number of examples of the successful transfer of styles from one model to another.
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    Compact Metallic Reflectance Models
    (Blackwell Publishers Ltd and the Eurographics Association, 1999) Neumann, Laszlo; Neumannn, Attila; Szirmay-Kalos, Laszlo
    The paper presents simple, physically plausible, but not physically based reflectance models for metals and other specular materials. So far there has been no metallic BRDF model that is easy to compute, suitable for fast importance sampling and is physically plausible. This gap is filled by appropriate modifications of the Phong, Blinn and the Ward models. The Phong and the Blinn models are known not to have metallic characteristics. On the other hand, this paper also shows that the Cook-Torrance and the Ward models are not physically plausible, because of their behavior at grazing angles. We also compare the previous and the newly proposed models. Finally, the generated images demonstrate how the metallic impression can be provided by the new models.
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    Comprehensive Halftoning of 3D Scenes
    (Blackwell Publishers Ltd and the Eurographics Association, 1999) Veryovka, O.; Buchanan, J.
    The display of images on binary output hardware requires a halftoning step. Conventional halftoning algorithms approximate image values independently from the image content and often introduce artificial texture that obscures fine details. The objective of this research is to adapt a halftoning technique to 3D scene information and thus to enhance the display of computer generated 3D scenes. Our approach is based on the control of halftoning texture by the combination of ordered dithering and error diffusion techniques. We extend our previous work and enable a user to specify the shape, scale, direction, and contrast of the halftoning texture using an external buffer. We control texture shape by constructing a dither matrix from an arbitrary image or a procedural texture. Texture direction and scale are adapted to the external information by the mapping function. Texture contrast and the accuracy of tone reproduction are varied across the image using the error diffusion process. We halftone images of 3D scenes by using the geometry, position, and illumination information to control the halftoning texture. Thus, the texture provides visual cues and can be used to enhance the viewer's comprehension of the display.
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    Computer-Generated Graphite Pencil Rendering of 3D Polygonal Models
    (Blackwell Publishers Ltd and the Eurographics Association, 1999) Sousa, Mario Costa; Buchanan, John W.
    Researchers in non-photorealistic rendering have investigated the display of three-dimensional worlds using various display models. In particular, recent work has focused on the modeling of traditional artistic media and styles such as pen-and-ink illustration and watercolor painting. By providing 3D rendering systems that use these alternative display models users can generate traditional illustration renderings of their three-dimensional worlds. In this paper we present our graphite pencil 3D renderer. We have broken the problem of simulating pencil drawing down into four fundamental parts: (1) simulating the drawing materials (graphite pencil and drawing paper, blenders and kneaded eraser), (2) modeling the drawing primitives (individual pencil strokes and mark-making to create tones and textures), (3) simulating the basic rendering techniques used by artists and illustrators familiar with pencil rendering, and (4) modeling the control of the drawing composition. Each part builds upon the others and is essential to developing the framework for higher-level rendering methods and tools. In this paper we present parts 2, 3, and 4 of our research. We present non-photorealistic graphite pencil rendering methods for outlining and shading. We also present the control of drawing steps from preparatory sketches to finished rendering results. We demonstrate the capabilities of our approach with a variety of images generated from 3D models.
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    Creating Architectural Models from Images
    (Blackwell Publishers Ltd and the Eurographics Association, 1999) Liebowitz, David; Criminisi, Antonio; Zisserman, Andrew
    We present methods for creating 3D graphical models of scenes from a limited numbers of images, i.e. one or two, in situations where no scene co-ordinate measurements are available. The methods employ constraints available from geometric relationships that are common in architectural scenes - such as parallelism and orthogonality - together with constraints available from the camera. In particular, by using the circular points of a plane simple, linear algorithms are given for computing plane rectification, plane orientation and camera calibration from a single image. Examples of image based 3D modelling are given for both single images and image pairs.
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    Data Intermixing and Multi-volume Rendering
    (Blackwell Publishers Ltd and the Eurographics Association, 1999) Cai, Wenli; Sakas, Georgios
    The main difference between multi-volume rendering and mono-volume rendering is data intermixing. In this paper, we present three levels of data intermixing and their rendering pipelines in direct multi-volume rendering, which discriminate image level intensity intermixing, accumulation level opacity intermixing, and illumination model level parameter intermixing. In the context of radiotherapy treatment planning, different data intermixing methods are applied to three volumes, including CT volume, Dose volume, and Segmentation volume, to compare the features of different data intermixing methods.
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    The Digital Michelangelo Project
    (Blackwell Publishers Ltd and the Eurographics Association, 1999) Levoy, Marc A.
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    Editorial
    (Blackwell Publishers Ltd and the Eurographics Association, 1999) Coquillart, Sabine; Seidel, Hans-Peter
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    Editorial
    (Blackwell Publishers Ltd and the Eurographics Association, 1999) Coquillart, Sabine; Seidel, Hans-Peter