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Computer Graphics and Applications, IEEE

Issue 2 • Date March-April 2000

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Displaying Results 1 - 13 of 13
  • 3D Dreams - The art of David Em

    Publication Year: 2000 , Page(s): 4 - 5
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    Freely Available from IEEE
  • How many different rational parametric cubic curves are there? 3. The catalog

    Publication Year: 2000 , Page(s): 85 - 88
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    The author is interested in rational parametric cubic curves, particularly in finding out how many essentially different shapes the given equation can make. Types of homogeneous cubic polynomials are considered. View full abstract»

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  • Metamorphosis of arbitrary triangular meshes

    Publication Year: 2000 , Page(s): 62 - 75
    Cited by:  Papers (26)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (812 KB)  

    Three-dimensional metamorphosis (or morphing) establishes a smooth transition from a source object to a target object. The primary issue in 3D metamorphosis is to establish surface correspondence between the source and target objects, by which each point on the surface of the source object maps to a point on the surface of the target object. Having established this correspondence, we can generate a smooth transition by interpolating corresponding points from the source to the target positions. We handle 3D geometric metamorphosis between two objects represented as triangular meshes. To improve the quality of 3D morphing between two triangular meshes, we particularly consider the following two issues: 1) metamorphosis of arbitrary meshes; 2) metamorphosis with user control. We can address the first issue using our recently proposed method based on harmonic mapping (T. Kanai et al., 1998). In that earlier work, we developed each of the two meshes (topologically equivalent to a disk and having geometrically complicated shapes), into a 2D unit circle by harmonic mapping. Combining those two embeddings produces surface correspondence between the two meshes. However, this method doesn't consider the second issue: how to let the user control surface correspondence. The article develops an effective method for 3D morphing between two arbitrary meshes of the same topology. We extend our previously proposed method to achieve user control of surface correspondence View full abstract»

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  • Choosing rendering parameters for effective communication of 3D shape

    Publication Year: 2000 , Page(s): 20 - 28
    Cited by:  Papers (2)  |  Patents (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (536 KB)  

    We conducted a series of perceptual experiments to assess the contributions of rendering parameters to the perception of the shape of three-dimensional objects. For the experiments, observers viewed graphically rendered displays consisting of pairs of rotating objects and judged whether their shapes were identical. For some pairs they were, while for other pairs they differed by varying amounts. We determined the accuracy of shape perception from these discrimination judgments. We provide background information for the operational definition of shape used throughout the experiments, as well as for the rendering factors under experimental investigation: occluding contour, smooth shading, and specular highlights. Following that, we describe a series of experiments. Experiment 1 demonstrated the effectiveness of our new technique for the exploration of perceptual issues related to graphic interfaces. An additional four experiments produced results concerning the effects of rendering parameters on the communication of 3D shape. Experiments 2 and 3 investigated the contributions of basic rendering conditions such as the presence of occluding contours and smooth surface shading. In Experiments 4 and 5, the manipulation of specular highlighting revealed that accurate shape discrimination judgments were possible either with or without the specular component. These results lay a foundation for reasoned manipulation of interface properties when accurate communication of 3D shape is a primary goal of the display View full abstract»

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  • Using a flatbed scanner as a stereoscopic near-field camera

    Publication Year: 2000 , Page(s): 38 - 45
    Cited by:  Papers (5)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (476 KB)  

    It is shown that flatbed scanners are inherently high quality 3D scanners. Currently developed first prototypes have many applications in industry and multimedia. Because of their big depth of focus, they can be used not only for scanning printed paper, but also for scanning small objects. The nonparallel optics also make it possible to create stereoscopic images of small objects with flatbed scanners, as first described elsewhere (R. Schubert, 1998). The author describes the method for doing this. He also shows examples of stereoscopic images made in this way so that you can judge for yourself their quality and particular properties. Finally, he describes possible accessories that will let you use flatbed scanners routinely in a lot of areas, including hobbies and professional applications. Combining dedicated 3D imaging and evaluation software as well as 3D output devices results in a high quality, low cost 3D scanner. Currently work is under way to specify, design, and build the first prototypes View full abstract»

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  • Maya: “So ya wanna be a rock 'n roll star” revisited [animation product]

    Publication Year: 2000 , Page(s): 7 - 11
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    In 1995, the company today known as Alias/Wavefront (A/W) held a press conference to announce its next-generation animation product, Maya. A/W claimed this future 3D animation tool would increasingly serve the artist, not the other way around. Maya addressed a basic problem: When artists working at a drafting table reach for a new pencil, they never look away from the part of the drawing they're working on. Artists at a workstation, on the other hand, must divert their eyes to choose the next tool from a series of nested menus. A/W concluded it should design its next-generation graphical user interface (GUI) around the notion of not forcing the artist to look away from the work area to keep working. One possible solution would organize the menus based on a compass metaphor (North, South, East, and West). Maya 1.0 for Irix was released in January 1998. It kept faith with the GUI promises, but implemented them in a different way: nested menus radiate in a compass layout centered on the current cursor position, allowing the eye to remain on the subject. Maya contains many features from A/W's flagship product, Power Animator, famous for its contributions to Terminator 2 and Jurassic Park among other films. It's both a character animation system and a soft/hard body dynamics environment. It will eventually replace Power Animator and include new technologies View full abstract»

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  • The digital ceraunoscope: synthetic thunder and lightning. I

    Publication Year: 2000 , Page(s): 89 - 93
    Cited by:  Papers (4)
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    The natural world is rich in complex and beautiful visual phenomena. Many of these are ripe for simulation by computer graphics. The author discusses digital lightning. His aim is to accurately match the natural phenomena, and not simply make something that could pass as an example of it View full abstract»

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  • Mosaicing ultrasonic volumes for visual simulation

    Publication Year: 2000 , Page(s): 53 - 61
    Cited by:  Papers (4)
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    The article addresses the problem of mosaicing a large volume from a set of small volumes acquired from a 3D ultrasound device. The formation of large volumes is necessary for an ultrasound visual simulator. Trainees using the simulator learn how to identify and diagnose a wide range of medical cases by operating a simulated ultrasound device on a mannequin, without any need for actual patients. The principle of the simulator is simple but apparently effective. In an offline preprocess, a volume buffer is generated from real ultrasound images. Slicing the volume buffer online then generates simulated images. Such images can be generated rapidly, including postprocessing enhancements, and can produce in most cases images indistinguishable from the real ultrasound images. The ultrasonic volume buffer has to be big enough and represent a large portion of the mannequin to permit the bound-free practice of a real-life diagnosis. Contemporary ultrasound devices don't provide the capability of obtaining the entire volume in a single acquisition. This implies that the volume buffer must be reconstructed from several subvolumes obtained from different viewpoints. The registration of monomodal data sets has been extensively investigated in medical applications where atlas data is used. The basic technique of a mosaicing operation aligns and registers two given volumes with a significant overlap into a single volume that smoothly combines the information from both. The type of registration technique that can be appropriately applied directly depends on the type of variation between the two volumes. Thus, designing a registration method requires knowing the type of variation exhibited by ultrasonic volumes View full abstract»

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  • The ambient spaces of computer graphics and geometric modeling

    Publication Year: 2000 , Page(s): 76 - 84
    Cited by:  Papers (2)
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    Four types of ambient mathematical spaces underlie the algebra and geometry of computer graphics and geometric modeling: vector spaces, affine spaces, projective spaces, and Grassmann spaces (H.G. Grassmann, 1894-1911). The author considers at length the theoretical advantages of the coordinate-free approach to understanding geometry. He focuses attention on the operations of addition, subtraction, and scalar multiplication because these are the operations best suited for the construction of freeform curves and surfaces. But there are also spaces with multiplicative structures: structures already coming into vogue in physics (D. Hestenes, 1992) and perhaps of use as well in the fields of computer graphics and computer aided design View full abstract»

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  • Data signatures and visualization of scientific data sets

    Publication Year: 2000 , Page(s): 12 - 15
    Cited by:  Papers (6)
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    Today, as data sets used in computations grow in size and complexity, the technologies developed over the years to deal with scientific data sets have become less efficient and effective. Many frequently used operations, such as eigenvector computation, could quickly exhaust our desktop workstations once the data size reaches certain limits. On the other hand, the high-dimensional data sets we collect every day don't relieve the problem. Many conventional metric designs that build on quantitative or categorical data sets cannot be applied directly to heterogeneous data sets with multiple data types. While building new machines with more resources might conquer the data size problems, the complexity of today's computations requires a new breed of projection techniques to support analysis of the data and verification of the results. We introduce the concept of a data signature, which captures the essence of a scientific data set in a compact format, and use it to conduct analysis as if using the original. A time-dependent climate simulation data set demonstrates our approach and presents the results View full abstract»

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  • Morphology-based data elimination from medical image data

    Publication Year: 2000 , Page(s): 46 - 52
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    Modern medical imaging lets us create accurate computer models of anatomical structures. Some of these models can be animated to visualize joint kinematics. A model's size and complexity can significantly affect the efficiency of any desired animation or interactive manipulation. The model normally takes the form of a polygonal mesh; the more facets in the mesh, the slower the rendering process. Beyond a certain limit, real time interaction becomes impractical because the frame rate (image regeneration) is too slow. The many methods proposed for reducing the number of polygons in computer models normally entail a loss of detail in the final model. In some applications, retaining detail may be important. Joint kinematics, which we were investigating, falls into this category, and we sought a way to reduce the input data volume without introducing a corresponding decrease in the isosurface resolution. Our application requires only the bone's external surface, which is found by segmenting radiological data obtained from computerized tomodensitometry (a CT scan). By analyzing local bone morphology, we were able to identify and eliminate nearly 50 percent of the polygons generated by standard segmentation techniques, while retaining the full resolution of the required isosurface. The article discusses the relationships between bone morphology and bone intensity in a medical imaging data set and describes how these relationships can help us reduce the polygon count in the surface models generated View full abstract»

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  • Speech/gesture interface to a visual-computing environment

    Publication Year: 2000 , Page(s): 29 - 37
    Cited by:  Papers (5)  |  Patents (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (544 KB)  

    We developed a speech/gesture interface that uses visual hand-gesture analysis and speech recognition to control a 3D display in VMD, a virtual environment for structural biology. The reason we used a particular virtual environment context was to set the necessary constraints to make our analysis robust and to develop a command language that optimally combines speech and gesture inputs. Our interface uses: automatic speech recognition (ASR), aided by a microphone, to recognize voice commands; two strategically positioned cameras to detect hand gestures; and automatic gesture recognition (AGR), a set of computer vision techniques to interpret those hand gestures. The computer vision algorithms can extract the user's hand from the background, detect different finger positions, and distinguish meaningful gestures from unintentional hand movements. Our main goal was to simplify model manipulation and rendering to make biomolecular modeling more playful. Researchers can explore variations of their model and concentrate on biomolecular aspects of their task without undue distraction by computational aspects. They can view simulations of molecular dynamics, play with different combinations of molecular structures, and better understand the molecules' important properties. A potential benefit, for example, might be reducing the time to discover new compounds for new drugs View full abstract»

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  • A voyage into virtual reality. Networking our VR lab to Iowa middle schools and high schools

    Publication Year: 2000 , Page(s): 16 - 19
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    The Iowa Communications Network (ICN) is a statewide, state administered, fiber optics network. Iowa State University (ISU) is one of the fiber optics endpoints and one of the main entities using the ICN to reach the Iowa community. As part of the ICN outreach activities at ISU, we are investigating how the ICN can be integrated with our research projects in virtual reality (VR). We're particularly interested in how the ICN can enable remote collaborations in immersive virtual environments with sites that don't have any or have limited local resources for VR. We present our first project with the ICN to bring our VR lab to remote middle schools and high schools in Iowa. This project was done in collaboration with Iowa Public Television (IPTV), another ICN endpoint. We connected to 86 schools simultaneously and reached about 2000 students. Ten sites were in interactive two-way video and audio mode. The rest were in viewing-only video and audio mode. We discuss the motivation, technical details, results, and future directions 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