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Computer Graphics and Applications, IEEE

Issue 5 • Date Sept.-Oct. 1997

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Displaying Results 1 - 11 of 11
  • Phantom-based haptic interaction with virtual objects

    Page(s): 6 - 10
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    In 1993, haptic interaction with computers took a significant step forward with the development of the Phantom haptic interface. This simple device has spawned a new field analogous to computer graphics-computer haptics-defined as the discipline concerned with the techniques and processes associated with generating and displaying synthesized haptic stimuli to the human user. Inspired by the authors' previous work in interpreting robot touch sensor information and study of human touch perception, the Phantom interface permits users to feel the forces of interaction they would encounter while touching objects with the end of a stylus or the tip of their finger. The resulting sensations prove startling, and many first-time users are quite surprised at the compelling sense of physical presence they encounter when touching virtual objects. To appreciate why the Phantom system succeeded where others failed, you need to understand the nature and functioning of the human haptic system. View full abstract»

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  • Rendering On A Fantasy

    Page(s): 4 - 5
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  • Simulation And Modeling

    Page(s): 15
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    First Page of the Article
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  • Using views for product data exchange

    Page(s): 58 - 65
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    Proprietary data structures complicate data sharing by making it difficult to save a product model from one software tool and load it directly into another tool. Engineers may want, for example, to verify with an analysis tool that all design constraints have been met or to prepare a design for manufacturing. In such cases, software developers must find a means of moving the product model from the proprietary data structures of a CAD system to those of the analysis system and the manufacturing system, with minimal loss of information. A database view, used in conjunction with data exchange standards, can facilitate the sharing of product model data between software tools in design and manufacturing computing environments View full abstract»

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  • The Solar System Modeler

    Page(s): 47 - 57
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    The authors undertook the Solar System Modeler project to improve comprehension and appreciation of the size, complexity, and splendor of the solar system. To do so, the Solar System Modeler must (1) accurately portray the orbital behavior of satellites, planets, comets, and other celestial bodies, and (2) function in a distributed virtual environment. Additionally, the system needs to: provide a flexible, 3D graphical user interface for immersive operation; assist the user in comprehending the state of the virtual environment; accurately portray the stars and their locations; graphically model all bodies throughout the solar system in 3D and to the same scale; and maintain an interactive frame rate. They describe how they met these requirements View full abstract»

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  • Modeling with features

    Page(s): 40 - 46
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    Existing freeform modeling methods do not address the needs of sculptors and animators, which differ from those of engineers. The authors' modeler fills this gap, allowing users to build shapes by adding bumps, dents, or twists anywhere on a parametric surface View full abstract»

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  • Visualization of prosthesis fit in lower-limb amputees

    Page(s): 16 - 29
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    Lower-limb prosthesis quality-of-fit assessment is purely subjective in routine clinical practice, relying on patient reports of discomfort, erythema (localized pain), and palpation. Wide variations in residual limb physical characteristics and conditions preclude a rigid approach to prosthesis prescription. With relatively long life expectancy for many lower-limb amputees, clinicians measure outcome in terms of return to work and quality of life, which have important social and economic consequences. An objective quantitative metric of fit that predicts functional outcome has not been described to date. Volumetric CT scanning provides in situ static 3D determination of residual limb soft tissue changes caused by the prosthesis socket. This mapping aids in prosthesis design and evaluation View full abstract»

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  • Digital orthophotography: mapping with pictures

    Page(s): 12 - 14
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    Aerial photographs and maps would seem a natural combination to record and analyze geographical information: maps provide geometric information and photographs add realistic, timely detail. But cameras record images on a flat plane, whereas the earth is curved and its terrain takes on many varied shapes-all of which distort the image geometry and render it invalid for mapping and geographic analysis. Digital orthophotographs solve this problem. A digital orthophoto starts with a rasterized (scanned) aerial photograph; a process called rectification (described below) removes distortions arising from the camera lens, the aircraft's position, and elevation and other topographical features. This transforms aerial photos into high-resolution digital images that correctly represent the geometry of an area and its terrain. These images can be used as standard true-scale representations of geographic sectors-a function already served by analog orthophotos, which must be painstakingly scanned and rectified in small strips or patches. Their fully digital format makes digital orthophotos useful as base maps in geographical information systems (GIS) used for creating and revising topographic and planimetric maps, vegetation and timber management, environmental impact assessments, and infrastructure assessment View full abstract»

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  • Simulation-based remote debriefing for Red Flag missions

    Page(s): 30 - 39
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    The Red Flag Measurement and Debriefing System reconstructs a mock air battle. A portable prototype system, the remote debriefing tool, helps merge the real and virtual environments. The research effort described by the authors investigated two areas not previously addressed by others: first, the inclusion of live participants in the synthetic environment, and second, a stealth viewer tailored to a specific task, in this case air-to-air combat training and debriefing. The stealth viewer supports the real-time extraction of important parameters related to air-to-air engagements, such as shot parameters including closing velocity and aspect angle View full abstract»

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  • The perils of problematic parameterization

    Page(s): 78 - 83
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    No matter how or when one uses polygons to approximate a curved surface, one needs to be very sure that they match that surface closely. The author can think of two ways to check this match: visually and mathematically. A visual check requires looking at the rendered imagery with a critical eye-if the surfaces look free of polygonal artifacts, then the approximation is good enough for that image. This is obviously pretty tough to quantize and implement in software. The mathematical approach suggests that one finds some descriptive measurement that one can apply to both the original model and the polygonal approximation. He evaluates the quality of a polygonal approximation to the original curved object by comparing their surface areas. If the areas are way off, something is wrong with the approximation. But even if the areas are the same, one can't say much. For example, one could start with a curved model of a lion and create a polygonal approximation of a bat. If they both have the same surface area, this measure won't tell one that there's any difference at all. On the other hand, if the areas are way off, one might be prompted to take a closer look. A folk theorem in graphics says if one wants to improve the quality of a polygonal approximation, one should use triangles, reduce their size, and use more of them, making sure of course that their vertices always lie on the surface. The resulting model can't help but get better and better View full abstract»

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  • Interactive space deformation with hardware-assisted rendering

    Page(s): 66 - 77
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    The authors introduce a new approach for the deformation of surface and raster models in two and three dimensions. Rather than deforming the model, they deform the agents employed to render it. The method uses one deformation tool (the deflector) to deform any object that is ray traceable. Based on deforming the rendering primitives rather than objects, the approach invests computation effort only in those regions of the model that contribute to the final image View full abstract»

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

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L. Miguel Encarnação
University of Iowa