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Computer Graphics and Applications, IEEE

Issue 4 • Date July-Aug. 2003

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Displaying Results 1 - 13 of 13
  • Music to the Eyes [About the Cover]

    Page(s): 4 - 5
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    Freely Available from IEEE
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  • A survey of stroke-based rendering

    Page(s): 70 - 81
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    This tutorial describes several stroke-based rendering (SBR) algorithms. SBR is an automatic approach to creating nonphotorealistic imagery by placing discrete elements such as paint strokes or stipples. View full abstract»

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  • Real-time animated stippling

    Page(s): 62 - 68
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    We present an approach to produce animations of 3D models using stippling as a rendering style. Our technique ensures frame-to-frame coherence as the model moves and changes over time. View full abstract»

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  • Visualization viewpoints

    Page(s): 20 - 25
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    User studies offer a scientifically sound method to measure a visualization's performance. Reasons abound for pursuing user studies, particularly when evaluating the strengths and weaknesses of different visualization techniques. A good starting point in any study is the scientific or visual design question to be examined. This drives the process of experimental design. A poorly designed experiment will yield results of only limited value. Although a comprehensive discussion of experimental design is beyond the scope of the article, we offer suggestions and lessons learned. We also describe how we designed experiments to answer important questions from our own research. View full abstract»

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  • Pervasive pose-aware applications and infrastructure

    Page(s): 14 - 18
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    Pose-aware devices, in concert with functional geometric models describing architectural spaces, enable a new class of indoor applications, including resource location, route finding, direct population and annotation of world models, and direct information overlay. The article describes these applications along with the device infrastructure and algorithms required to support them. We demonstrate a few prototype devices and applications now underway and point to future directions in which these techniques might evolve. View full abstract»

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  • A developer's guide to silhouette algorithms for polygonal models

    Page(s): 28 - 37
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    Silhouettes play an important role in shape recognition because they provide one of the main cues for figure-to-ground distinction. However, since silhouettes are view dependent, they need to be determined for every frame of an animation. Finding an efficient way to accomplish this is nontrivial. Indeed, a variety of different algorithms exist that compute silhouettes for geometric objects. This article provides a guideline for developers who need to choose between one of these algorithms for his or her application. We restrict ourselves to discussing only those algorithms that apply to polygonal models, because these are the most commonly used object representations in modern computer graphics. Thus, we can use all algorithms discussed to take a polygonal mesh as input and compute the visible part of the silhouette as output. Some algorithms, however, can also help compute the silhouette only, without additional visibility culling. The silhouette's representation might vary depending on the algorithm class - that is, the silhouette might take the form of a pixel matrix or a set of analytic stroke descriptions. View full abstract»

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  • Stylized highlights for cartoon rendering and animation

    Page(s): 54 - 61
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    We propose a new highlight shader for the 3D objects used in cel animation. Without using a texture-mapping technique, our shader makes highlight shapes and animations in a cartoon style. Our shader makes an initial highlight shape using Blinn's (1977) traditional specular model. It then interactively modifies the initial shape through geometric, stylistic, and Boolean transformations for the highlight until we get our final desired shape. Moreover, once these operations specify highlight shapes for each keyframe, our shader automatically generates the highlight animation. In other words, our shader offers a new definition of highlighting 3D objects for cel animation. View full abstract»

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  • Lines in space

    Page(s): 96 - 101
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    Previously we came up with two algebraic representations for lines in 3D projective space: we got one from connecting two points and the other from intersecting two planes. In both cases the algebraic representation was an antisymmetric 4 × 4 matrix, but these two matrices were not the same. In this paper, we try to understand these differences and see how to convert one to the other. We become more acquainted with the properties of these matrices and build up some intuition on the geometric meaning of their components. We do all the algebra using what we call conventional, or familiar, notation. This gives letter names to each element of a vector/matrix and gives a sense of concreteness to the calculations. This makes the reader really appreciate the newer Einstein index notation and its alternate representation, tensor diagrams. View full abstract»

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  • Venn and now

    Page(s): 82 - 95
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    One of the most famous visual tools for logic is the Venn diagram, which most frequently shows the relationship between three object classes by drawing three overlapping circles. I discuss Venn diagrams, how they can be generalized to more than three sets of objects, and related tools for visual logic. View full abstract»

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  • Understanding fire and smoke flow through modeling and visualization

    Page(s): 6 - 13
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    Computer modeling and visualization are important tools for understanding the processes of fire behavior. Fire models range in complexity from simple correlations for predicting quantities such as flame heights or flow velocities to moderately complex zone fire models for predicting time-dependent smoke layer temperatures and heights. Zone fire model calculations can run on today's computers within minutes because they solve only four differential equations per room. Zone models approximate the entire upper layer with just one temperature. This approximation works remarkably well but breaks down for complicated flows or geometries. For such cases, computational fluid dynamics (CFD) techniques are required. View full abstract»

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  • Nonphotorealistic rendering of medical volume data

    Page(s): 44 - 52
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    The article introduces volumetric hatching, a novel technique that produces pen-and-ink-style images from medical volume data. Unlike previous approaches that generate full-surface models, our technique uses characteristics of the volume near the stroke being produced to generate a local intermediate surface. Because global isosurfaces can't exactly model many medical subjects, our volume-based method has considerable advantages. Our method is largely insensitive to surface artifacts. We focus on hatching with line strokes to portray muscles, intestines, brains, and so on. Hatching with line strokes requires determining not just the position of the line strokes, but also their orientation. Thus, the strokes not only illustrate the subject's shape, but also describe its character in some way - for example, by displaying fiber orientations for muscles. View full abstract»

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  • Fast texture transfer

    Page(s): 38 - 43
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    The article presents an algorithm for texture transfer between images that is up to several orders of magnitude faster than current state-of-the-art techniques. I demonstrate how the technique can leverage self-similarity of complex images to increase resolution of some types of images and to create novel, artistic looking images from photographs without any prior artistic source. Compared to other alternatives, methods based on texture transfer are global in the sense that the user need not deal with details such as defining and painting individual brush strokes. Texture transfer methods are also more general since they don't need to emulate any particular artistic style (line drawing, hatching, realistic oil painting, and so on). Not surprisingly, there is a price to pay for this generality - an algorithm designed for a specific artistic style will most likely produce results superior to those presented in the paper for that particular case. View full abstract»

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IEEE Computer Graphics and Applications bridges the theory and practice of computer graphics.

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Meet Our Editors

Editor-in-Chief
L. Miguel Encarnação
University of Iowa