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XII Brazilian Symposium on Computer Graphics and Image Processing (Cat. No.PR00481)

17-20 Oct. 1999

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  • XII Brazilian Symposium on Computer Graphics and Image Processing (Cat. No.PR00481)

    Publication Year: 1999
    Request permission for commercial reuse | PDF file iconPDF (202 KB)
    Freely Available from IEEE
  • Anno 2010-remembering our future. Challenges and frontiers of visualization for Human-Media Technology as the kernel for Human-Centered Computing

    Publication Year: 1999
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (6 KB)

    Summary form only given. Human-Media-Technology is one of the "technology's top 10 challenges and opportunities" for the year 2010. The subject hereby is: "humans live, science finds out how technology conforms." The goal is to develop environments that allow users to cooperate in the most efficient and natural way. Human-centered systems will have to incorporate people as an explicit design compo... View full abstract»

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  • Characterization of linear and morphological operators

    Publication Year: 1999
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (4 KB)

    Summary form only given, as follows. In image processing, the transformations of an image to another one are obtained through operators. Among the most important operators are the linear operators and the morphological ones (dilations and erosions). We recall the definition of these operators and present an algebraic characterization of them for the case of spatial invariance. The importance of th... View full abstract»

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  • Accurate building structure recovery from aerial imagery

    Publication Year: 1999
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (3 KB)

    Summary form only given, as follows. In this paper, we discuss methods for the detection and reconstruction of buildings from aerial imagery. These methods have been intended for the analysis of urban and suburban areas and have been applied to images of different resolutions (between 1 m and 10 cm per pixel). Various algorithms for image matching have been investigated, including hierarchical pro... View full abstract»

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  • Index of authors

    Publication Year: 1999, Page(s): 357
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    Freely Available from IEEE
  • An optimal algorithm to construct all Voronoi diagrams for k nearest neighbor search in T2

    Publication Year: 1999, Page(s):7 - 15
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (192 KB)

    We generalize to the oriented projective plane T2 an algorithm for constructing all order k Voronoi diagrams in the Euclidean plane. We also show that, for fixed k and for a finite set of sites, an order k Voronoi diagram in T2 has an exact number of regions. Furthermore, we show that the order k Voronoi diagram of a set of n sites in T2 is antipodal to its order n... View full abstract»

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  • Real-time shadow generation using BSP trees and stencil buffers

    Publication Year: 1999, Page(s):93 - 102
    Cited by:  Papers (6)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (884 KB)

    This paper describes a real-time shadow generation algorithm for static polygonal environments illuminated by movable point light sources. The algorithm combines a technique of volumetric shadow rendering using stencil buffers with a binary space partitioning (BSP) tree, and includes new easy-to-implement approaches to improvement techniques used in shadow volume algorithms, such as silhouette det... View full abstract»

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  • Motion cyclification by time×frequency warping

    Publication Year: 1999, Page(s):49 - 58
    Cited by:  Papers (3)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (308 KB)

    This paper presents a new algorithm for the cyclification of 1D signals, based on a time×frequency warping. The main goal is to preserve the basic characteristics of the signal, such as low and high frequency regions. The application outlined in this work is the cyclification of motion captured joint curves (near-periodic signals). Also, a method for cyclification of articulated figure motio... View full abstract»

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  • The 𝒢0A distribution as the true model for SAR images

    Publication Year: 1999, Page(s):327 - 336
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (508 KB)

    For many synthetic aperture radar (SAR) sensors, urban areas, forests and pasture areas have a growing degree of homogeneity, and for each one of these region types there is a distribution class that fits the data best. In this paper, the feasibility of using the 𝒢0 A distribution as a general model is studied, and the practical usefulness of this proposal is shown. The ... View full abstract»

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  • Control point assessment for image registration

    Publication Year: 1999, Page(s):125 - 132
    Cited by:  Papers (2)  |  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (144 KB)

    Presents several extensions of the basic control point assessment (CPA) algorithm. First, we compare CPA to standard corner detection algorithms and then turn to the question of selecting control points with adequate dispersion, since this is crucial for accurate registration. Two selection methods are proposed. The first consists of clustering the control points via the Lloyd algorithm (S.P. Lloy... View full abstract»

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  • Multiple display viewing architecture for virtual environments over heterogeneous networks

    Publication Year: 1999, Page(s):83 - 92
    Cited by:  Papers (4)  |  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (88 KB)

    Visualization systems that support multiple-display viewing can greatly enhance user perception. The common approach to provide multiple synchronized views uses a powerful centralized processing unit to support the rendering process on all screens. As an alternative approach, we propose a distributed architecture that supports a flexible and reliable visualization system that, while giving the use... View full abstract»

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  • Automatic design of morphological operators for motion segmentation

    Publication Year: 1999, Page(s):283 - 292
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (360 KB)

    A problem of interest in digital video editing is the elimination of moving objects from one video and the introduction of pieces of other videos in their places. A fundamental problem to build computational tools for this purpose is the segmentation of moving objects. The paper approaches this problem with a novel technique based on Beucher-Meyer's paradigm (F. Meyer and S. Beucher, 1990), with m... View full abstract»

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  • Interpolation of scattered data: investigating alternatives for the modified Shepard method

    Publication Year: 1999, Page(s):39 - 47
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (292 KB)

    Many scientific applications use scattered data originating from samples. Interpolation techniques are necessary to estimate the values on non-sampled regions. In previous work, the modified Shepard interpolation method was implemented and some unpredictable results occurred. Due to the flexibility of parameter definition for interpolant generation in this method we decided to investigate solution... View full abstract»

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  • Simulation of correlated intensity SAR images

    Publication Year: 1999, Page(s):317 - 326
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (720 KB)

    This paper discusses some methods already available for the simulation of correlated heterogeneous targets in synthetic aperture radar (SAR) images, and extends one of these methods. This new technique is based on the use of a correlation mask and Gaussian random variables, in order to obtain spatially dependent Gamma deviates. Its theoretical properties are presented, along with an algorithm. The... View full abstract»

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  • Curvature operators in geometric image processing

    Publication Year: 1999, Page(s):223 - 230
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (216 KB)

    We study the problem of reconstructing an image from a perceptual segmentation based on a geometric classification of its points using non-linear curvature filters. We give a mathematical proof that an image can be reconstructed from the regions of non-zero Gaussian curvatures. This result provides the theoretical background for a new theory of non-linear two dimensional signal processing as propo... View full abstract»

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  • Piecewise trilinear deformation of tomographic models

    Publication Year: 1999, Page(s):113 - 122
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (232 KB)

    Introduces an iterative method that deforms brain models built from tomographic images. The deformation is used for normalization purposes: individual models are deformed to match the shape, orientation and internal morphology of a reference model. In this method, the individual and the reference models are each enclosed in a cube which is subdivided to form a rectangular grid. The vertices in the... View full abstract»

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  • A framework for attention and object categorization using a stereo head robot

    Publication Year: 1999, Page(s):143 - 152
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (152 KB)

    Describes a framework for dealing with attention and categorization using a robot platform consisting of an articulated stereo head with four degrees of freedom (pan, tilt, left verge and right verge). As a practical result of this development, the system can select a region of interest, perform shifts of attention involving saccadic movements, perform efficient feature extraction and object ident... View full abstract»

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  • Efficient visualization of graphical objects

    Publication Year: 1999, Page(s):73 - 81
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (752 KB)

    The use of appropriate data structures for storing sets of graphical objects can lead to great performance improvements in the visualization of large figures, such as maps and CAD drawings. We present a study on the performance of persistent data structures composed of an R-tree and V-trees, for storing and efficiently retrieving 2D graphical objects. Results are shown to demonstrate the efficienc... View full abstract»

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  • Pitfalls in public key watermarking

    Publication Year: 1999, Page(s):241 - 242
    Cited by:  Papers (2)  |  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (196 KB)

    The cryptographic concept of digital signatures is well suited to image watermarking for authentication and integrity verification. However, the peculiar nature of watermarks demands special care in the application of digital signatures for this purpose. We cryptanalyze a recently proposed watermarking scheme and show how it can be strengthened to thwart our attacks, exploring the use of hashing f... View full abstract»

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  • A simple algorithm for decomposing convex structuring elements

    Publication Year: 1999, Page(s):275 - 282
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (240 KB)

    A finite subset of Z2 is called a structuring element. The paper presents a new and simple algorithm for decomposing a convex structuring element as a sequence of Minkowski additions of a minimum number of subsets of the elementary square (i.e., the 3×3 square centered at the origin). Besides its simplicity, the advantage of this algorithm over some known algorithms is that it gen... View full abstract»

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  • An algorithm for two-dimensional mesh generation for arbitrary regions with cracks

    Publication Year: 1999, Page(s):29 - 38
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (600 KB)

    This paper describes an algorithm for generating unstructured triangulations for arbitrarily shaped two-dimensional regions. The algorithm works for regions without cracks, as well as for regions with one or multiple cracks. The algorithm incorporates aspects of well-known meshing procedures and includes some original steps. It includes an advancing front technique, which uses a quadtree procedure... View full abstract»

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  • The granulometric size density in filter optimization

    Publication Year: 1999, Page(s):257 - 264
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (76 KB)

    Binary granulometric filters are constructed from parameterized unions and intersections of morphological openings. They are especially useful in filtering out clutter when an observed image is composed of a signal unioned with the clutter; however, their general theory does not depend on this model. More generally, the granulometric spectral theory provides a set decomposition in which bands with... View full abstract»

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  • Parallelizing MPEG video encoding using multiprocessors

    Publication Year: 1999, Page(s):215 - 222
    Cited by:  Papers (7)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (80 KB)

    Many computer applications are currently using digital video. Recent advances in digital imaging and faster networking infrastructure made this technology very popular, not only for entertainment, but also in health and education applications. However, high quality video requires more storage space and communication bandwidth than traditional data. To deal with this problem, most of the digital vi... View full abstract»

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  • Quasi 4-8 subdivision surfaces

    Publication Year: 1999, Page(s):17 - 26
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (752 KB)

    This paper presents a new scheme for subdivision surfaces that is based on four-directional meshes. It combines geometry-sensitive refinement with convolution smoothing. The scheme has a simple, efficient implementation and generates well-shaped meshes which converge to smooth surfaces View full abstract»

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  • Fast digital perspective shell rendering

    Publication Year: 1999, Page(s):105 - 111
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (108 KB)

    Volume visualization methods usually require extensive storage and time-intensive computations. To make them viable in many applications, researchers have proposed various types of hardware-based and software-based solutions. In most of these solutions, the rendering is based on orthographic parallel projection. However, in applications such as virtual endoscopy, perspective projection is necessar... View full abstract»

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