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Computer Graphics and Applications, IEEE

Issue 5 • Date Sept. 1996

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Displaying Results 1 - 13 of 13
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  • Visualizing production planning data

    Page(s): 7 - 10
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (860 KB)  

    Visualization of production planning data for decision making in manufacturing is nearly nonexistent. The planning problems at the Electronic Card Assembly and Test plant (ECAT) at IBM Austin, Texas, prompted the research project reported in this article. The project studied the characteristics of this type of managerial data, then developed special visualization techniques for constructing visual representations to support planners in developing superior production plans. A visualization prototype called VIZ planner was designed, implemented and empirically evaluated in a laboratory setting. Using this tool, hundreds of products, thousands of components, and many other factors can be visualized to provide planners with production planning insight View full abstract»

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  • Fitting a woven cloth model to a curved surface: dart insertion

    Page(s): 60 - 70
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    If a woven cloth composite “ply” cannot fit a surface exactly, “darts” must be cut. Algorithms that define these darts for a CAD system resolve anomalies in the 3D ply View full abstract»

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  • 3D scanning in apparel design and human engineering

    Page(s): 11 - 15
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    Much work remains before 3D anthropometric imaging systems can be used successfully in automated apparel design and other applications requiring accurate human body size data. Furthermore, the development of basic anthropometric data extraction tools and other related application software must be greatly enhanced, regardless of the scanner type or proposed application. Still, based on current progress, the potential of 3D anthropometric imaging seems tremendous. Certainly, the costs and benefits will become more apparent with time. Probably, a given method might suit some applications and not others, according to variables such as data acquisition and processing speed, system resolution, data accuracy and color. Technical differences aside, as long as a given system can consistently generate surface data to a known level of precision-a level acceptable for the application at hand-the system should find broad acceptance. Finally, only careful testing and validation of new applications can ensure the long-term usefulness of any data collection system, 3D or otherwise View full abstract»

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  • An evolving system for simulating clothes on virtual actors

    Page(s): 42 - 51
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1756 KB)  

    This cloth modeling and animation system aims to support virtual actors who can dress and undress themselves. It now creates autonomous clothes, independent of the synthetic human wearing them. The interactive editor, proportion box and body-scaling feature provide a set of intuitive tools for animators to design a rich variety of human shapes, and we have shown how to dress them with autonomous clothes. The new software considerably improves system performance, versatility and ease of use, and our goal of simulating actors that can dress and undress themselves is significantly closer View full abstract»

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  • Fun with premultiplied alpha

    Page(s): 86 - 89
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    The computer graphics universe consists of pixels. Pixels, in turn, consist of components: red, green, blue, and the coverage or opacity value alpha. For various reasons it is convenient to store and process a given rgbα quadruple with the rgb values already multiplied by α. This was first pointed out in the original Porter-Duff compositing paper (1984) and I presented some further justifications in an earlier column (“Image Compositing-Theory”, ibid., p.83-7, Sept. 1994). This premultiplication has some other interesting implications, and that's what I discuss this time View full abstract»

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  • Finite-element modeling and control of flexible fabric parts

    Page(s): 71 - 80
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    Software based on nonlinear shell theory can simulate 3D motions related to real fabric-manufacturing processes. This simulation capability advances the technologies necessary for automating the textile and apparel industries View full abstract»

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  • Driving simulation: challenges for VR technology

    Page(s): 16 - 20
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    Virtual driving environments represent a challenging test for virtual reality technology. We present an overview of our work on the problems of scenario and scene modeling for virtual environments (VEs) in the context of the Iowa Driving Simulator (IDS). The requirements of driving simulation-a deterministic real-time software system that integrates components for user interaction, simulation, and scenario and scene modeling-make it a valuable proving ground for VE technologies. The goal of our research is not simply to improve driving simulation, but to develop technology that benefits a wide variety of VE applications. For example, our work on authoring high-fidelity VE databases and on directable scenarios populated with believable agents also targets applications involving interaction with simulated, walking humans and training in the operation of complex machinery. This work has benefited greatly from the experience of developing components for a full-scale operational VE system like IDS, and we believe that many other proposed VE technologies would similarly benefit from such real-world testing View full abstract»

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  • More origami solids

    Page(s): 81 - 85
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    There are a bunch of interesting programming projects hiding within the subject of origami, and unit origami in particular. Certainly one of the most straightforward is to write a program that will read some form of origami notation and create a 3D geometry file of the result, which you can then render. Or you can use the same information to create folding diagrams. These are both very hard problems if you go into them deeply. The folding problem requires keeping track of the thickness of the paper at each fold and how bit slides around (for example, if you have two layers of paper involved in a fold, the outermost layer requires more paper than the inner layer). The diagramming problem is pretty tricky, because getting the right point of view and picking the right steps to illustrate it are very personal choices. I made the diagrams in these two columns by hand with a computer-aided drafting program. With my trusty calculator, I computed all the angles and lengths to make sure that everything lined up just where it ought to View full abstract»

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  • It's really not a rendering bug, you see

    Page(s): 21 - 25
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1228 KB)  

    Most rendering algorithms deliberately employ approximations and other shortcuts for efficiency. These economies-not coding errors-produce characteristic image artifacts. This article classifies the best-known varieties. We wrote this article in the hope of saving programmers a lot of time debugging something that is really not a bug, but instead a limitation of the algorithm. Our taxonomy is not exhaustive, but it does include many common rendering problems that we have encountered over the years. Most of these limitations can be circumvented with the proposed solutions. In reality, there are more workarounds than true solutions. This imbalance warrants more research into proper solutions to these and similar problems View full abstract»

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  • A fast, flexible, particle-system model for cloth draping

    Page(s): 52 - 59
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    Animating the drape of different cloths must address complex physical behaviors. This particle approach uses optimizations that make it faster than earlier implementations and allow it to simulate behavior over time. The modeling system presented computes the full trajectories of particles and not just the final positions. This offers several important advantages. Since the full history of each particle is known, hysteresis effects can be modeled accurately. The Kawabata (1980) experimental data for different textiles can be input directly to the model. The effects of external forces, especially those produced by wind or moving solid bodies, can be modeled accurately. Despite this extra dimension of detail, our system computes final positions considerably faster than the times given by Breen, House and Wozny (1994). Our model can be easily extended to simulate the effects of manufacturing processes or interacting bodies. In particular, high stresses of the kind that occur in manufacturing can only be modeled if the full trajectory of each particle is known. We have implemented our model as a C++ class library. Particle systems are more flexible than approaches using continuum mechanics. Our system's fast computation times, mainly due to the numerical solution of ordinary differential equations, compare favorably to approaches using a finite-element method. Therefore, our approach might be an interesting alternative for other engineering problems currently solved by a finite-element method, for example, the computation of minimal surfaces, heavy membranes, vibrating membranes and population dynamics View full abstract»

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  • Computer graphics techniques for modeling cloth

    Page(s): 28 - 41
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    In this survey, we present a contemporary overview of cloth modeling techniques. 19 modeling techniques are summarized and categorized by their main theoretical method: geometrical, physical, or hybrid. The techniques within each category do not follow well-defined patterns. We therefore generally report each work independently according to the chronology of publication. At the end of the discussion of all techniques, we summarize their features in a table. We conclude by speculating on future research directions that could optimize the agreement between the requirements of visual realism and physical accuracy. The recommendations for future work consider the different goals in textile engineering and computer graphics View full abstract»

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

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