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Visualization and Computer Graphics, IEEE Transactions on

Issue 2 • Date June 1996

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Displaying Results 1 - 8 of 8
  • Efficient triangular surface approximations using wavelets and quadtree data structures

    Publication Year: 1996 , Page(s): 130 - 143
    Cited by:  Papers (33)  |  Patents (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2577 KB)  

    We present a method for adaptive surface meshing and triangulation which controls the local level of detail of the surface approximation by local spectral estimates. These estimates are determined by a wavelet representation of the surface data. The basic idea is to decompose the initial data set by means of an orthogonal or semi orthogonal tensor product wavelet transform (WT) and to analyze the resulting coefficients. In surface regions, where the partial energy of the resulting coefficients is low, the polygonal approximation of the surface can be performed with larger triangles without losing too much fine grain details. However, since the localization of the WT is bound by the Heisenberg principle, the meshing method has to be controlled by the detail signals rather than directly by the coefficients. The dyadic scaling of the WT stimulated us to build an hierarchical meshing algorithm which transforms the initially regular data grid into a quadtree representation by rejection of unimportant mesh vertices. The optimum triangulation of the resulting quadtree cells is carried out by selection from a look up table. The tree grows recursively as controlled by detail signals which are computed from a modified inverse WT. In order to control the local level of detail, we introduce a new class of wavelet space filters acting as "magnifying glasses" on the data. We show that our algorithm performs a low algorithmic complexity, so that surface meshing can be achieved at interactive rates, such as required by flight simulators, however, other applications are possible as well. View full abstract»

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  • Correction - A Near Optimal Isosurface Extraction Algorithm Using the Span Space

    Publication Year: 1996
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (114 KB)  

    First Page of the Article
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  • Controlled topology simplification

    Publication Year: 1996 , Page(s): 171 - 184
    Cited by:  Papers (21)  |  Patents (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2028 KB)  

    We present a simple, robust, and practical method for object simplification for applications where gradual elimination of high frequency details is desired. This is accomplished by converting an object into multi resolution volume rasters using a controlled filtering and sampling technique. A multiresolution triangle mesh hierarchy can then be generated by applying the Marching Cubes algorithm. We further propose an adaptive surface generation algorithm to reduce the number of triangles generated by the standard Marching Cubes. Our method simplifies the topology of objects in a controlled fashion. In addition, at each level of detail, multilayered meshes can be used for an efficient antialiased rendering View full abstract»

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  • Interactive time-dependent particle tracing using tetrahedral decomposition

    Publication Year: 1996 , Page(s): 120 - 129
    Cited by:  Papers (22)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1168 KB)  

    Streak lines and particle traces are effective visualization techniques for studying unsteady fluid flows. For real time applications, accuracy is often sacrificed to achieve interactive frame rates. Physical space particle tracing algorithms produce the most accurate results although they are usually too expensive for interactive applications. An efficient physical space algorithm is presented which was developed for interactive investigation and visualization of large, unsteady, aeronautical simulations. Performance has been increased by applying tetrahedral decomposition to speed up point location and velocity interpolation in curvilinear grids. Preliminary results from batch computations showed that this approach was up to six times faster than the most common algorithm which uses the Newton-Raphson method and trilinear interpolation. Results presented show that the tetrahedral approach also permits interactive computation and visualization of unsteady particle traces. Statistics are given for frame rates and computation times on single and multiprocessors. The benefits of interactive feature detection in unsteady flows are also demonstrated View full abstract»

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  • Efficient streamline, streamribbon, and streamtube constructions on unstructured grids

    Publication Year: 1996 , Page(s): 100 - 110
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1624 KB)  

    Streamline construction is one of the most fundamental techniques for visualizing steady flow fields. Streamribbons and streamtubes are extensions for visualizing the rotation and the expansion of the flow. The paper presents efficient algorithms for constructing streamlines, streamribbons, and streamtubes on unstructured grids. A specialized Runge-Kutta method is developed to speed up the tracing of streamlines. Explicit solutions are derived for calculating the angular rotation rates of streamribbons and the radii of streamtubes. In order to simplify mathematical formulations and reduce computational costs, all calculations are carried out in the canonical coordinate system instead of the physical coordinate system. The resulting speed up in overall performance helps explore large flow fields View full abstract»

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  • Feature extraction and iconic visualization

    Publication Year: 1996 , Page(s): 111 - 119
    Cited by:  Papers (24)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1316 KB)  

    We present a conceptual framework and a process model for feature extraction and iconic visualization. The features are regions of interest extracted from a dataset. They are represented by attribute sets, which play a key role in the visualization process. These attribute sets are mapped to icons, or symbolic parametric objects, for visualization. The features provide a compact abstraction of the original data, and the icons are a natural way to visualize them. We present generic techniques to extract features and to calculate attribute sets, and describe a simple but powerful modeling language which was developed to create icons and to link the attributes to the icon parameters. We present illustrative examples of iconic visualization created with the techniques described, showing the effectiveness of this approach View full abstract»

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  • Splatting of non rectilinear volumes through stochastic resampling

    Publication Year: 1996 , Page(s): 156 - 170
    Cited by:  Papers (11)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1768 KB)  

    The paper extends the conventional splatting algorithm for volume rendering non rectilinear grids. A stochastic sampling technique called Poisson sphere/ellipsoid is employed to adaptively resample a non rectilinear grid with a set of randomly distributed points whose energy support extents are well approximated by spheres or ellipsoids. Then volume rendered images can be generated by splatting the scalar values at the new sample points with filter kernels corresponding to these spheres and ellipsoids. Experiments have been carried out to investigate the image quality as well as the time/space efficiency of the new approach, and the results suggest that our approach can be regarded as an alternative for existing fast volume rendering techniques of non rectilinear grids View full abstract»

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  • Volumetric data exploration using interval volume

    Publication Year: 1996 , Page(s): 144 - 155
    Cited by:  Papers (20)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1660 KB)  

    A new type of geometric model called Interval volume for volumetric data exploration is presented. An interval volume represents a three dimensional subvolume for which the associate scalar values lie within a user specified interval, and provides one of the promising approaches to solid fitting, which is an extended concept of traditional surface fitting. A well known isosurfacing algorithm called Marching Cubes is extended to obtain a solid fitting algorithm, which extracts from a given volumetric data set a high resolution, polyhedral solid data structure of an interval volume. Branch-on-Need Octree is used as an auxiliary data structure to accelerate the extraction process. A variety of interval volume rendering methods and principal related operations, including measurements and focusing, are also presented. The effectiveness of measurement coupled visualization capabilities of the presented approach is demonstrated by application to visualizing a four dimensional simulated data from atomic collision research View full abstract»

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Aims & Scope

Visualization techniques and methodologies; visualization systems and software; volume visualization; flow visualization; multivariate visualization; modeling and surfaces; rendering; animation; user interfaces; visual progranuning; applications.

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Meet Our Editors

Editor-in-Chief
Leila De Floriani
Department of Computer Science, Bioengineering, Robotics and Systems Engineering
University of Genova
16146 Genova (Italy)
ldf4tvcg@umiacs.umd.edu