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
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    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
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    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
  • Mesh collapse compression

    Publication Year: 1999, Page(s):27 - 28
    Cited by:  Papers (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (72 KB)

    We present a novel algorithm for encoding the topology of triangular meshes. A sequence of edge contract and divide operations collapses the entire mesh into a single vertex. This implicitly creates a tree with weighted edges. The weights are vertex degrees and capture the topology of the unlabeled mesh. The nodes are vertices and capture the labeling of the mesh. This weighted-edge tree has a ver... 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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  • 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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  • 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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  • 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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  • Shape preservation in morphological filtering and segmentation

    Publication Year: 1999, Page(s):247 - 256
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (168 KB)

    The paper discusses the behavior of some image filtering and segmentation approaches, focusing on techniques that belong to mathematical morphology. In particular, the article studies some morphological operators and filters that consider connectivity in a special way and that therefore satisfactorily preserve the significant shapes and contours of an input image. Such morphological connected filt... View full abstract»

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  • Interval methods for ray casting implicit surfaces with affine arithmetic

    Publication Year: 1999, Page(s):65 - 71
    Cited by:  Papers (9)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (124 KB)

    We study the performance of affine arithmetic as a replacement for interval arithmetic in interval methods for ray casting implicit surfaces. Affine arithmetic is a variant of interval arithmetic designed to handle the dependency problem, and which has improved several interval algorithms in computer graphics 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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  • A new paradigm for the architecture of morphological machines: binary decision diagrams

    Publication Year: 1999, Page(s):293 - 301
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (224 KB)

    A central paradigm in mathematical morphology (MM) is the representation of set operators in terms of erosions, intersection, union, complementation and composition. The hardware or software that implements this decomposition structure is called a morphological machine (MMach). The architecture of all known MMachs has as central characteristic: a small kernel with very fast procedures. Another wel... View full abstract»

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  • Using adaptive contraction for fractal image coding based on local fractal dimension

    Publication Year: 1999, Page(s):231 - 239
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (872 KB)

    In automatic fractal image compression, most of the encoding time is spent on finding the best match between each range block and the domain blocks. We propose the use of the local complexity of the image domain blocks to reduce the number of pairs to be tested on this search. Indexing the contracted domain pools according to their local fractal dimension and using multiple contraction factors we ... View full abstract»

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  • Keeping an eye for HCI

    Publication Year: 1999, Page(s):171 - 176
    Cited by:  Papers (22)  |  Patents (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (112 KB)

    Advanced human-computer interaction (HCI) techniques are required to enhance current computer interfaces. In this paper, we present an eye gaze tracking system based on a robust low-cost real-time pupil detector, and we describe some eye-aware applications that are being developed to enhance HCI. Images of pupils are segmented using an active lighting scheme that exploits very particular propertie... View full abstract»

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  • Visual tracking of objects using multiresolution

    Publication Year: 1999, Page(s):153 - 160
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (412 KB)

    Presents a methodology for multiple object tracking in image sequences at a high video rate using a multi-resolution technique based on the Haar basis of the wavelet transform. The main objective of visual tracking is to closely follow objects in each frame of a video stream such that the object position and other geometric information are always known. The idea is to locate and accompany an objec... 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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  • 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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  • A methodology for 3D registration of range images for object visualization

    Publication Year: 1999, Page(s):133 - 141
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (216 KB)

    This paper describes an image description method in VRML, using a device for 3D image acquisition. The information obtained from the capture of each object face is organized, and a description of the scanned object is made in the VRML format. This paper presents a study of the minimum number of captures that is necessary to obtain a complete description of the object. The paper shows the problems ... 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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  • 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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  • 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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  • 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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  • A Monte-Carlo study of classical spectral estimation of the backscatter in k-distributed images

    Publication Year: 1999, Page(s):337 - 346
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (536 KB)

    Some estimators for the spectral density of the return in synthetic aperture radar (SAR) images are studied using Monte Carlo experiences. The spectral density is an important quantifier of the texture that, in turn, can be related to biophysical magnitudes and it can be used to establish the kind of target being observed. These images are contaminated by a particular kind of noise, called speckle... View full abstract»

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