By Topic

Computer Graphics, Image Processing, and Vision, 1998. Proceedings. SIBGRAPI '98. International Symposium on

20-23 Oct. 1998

Filter Results

Displaying Results 1 - 25 of 65
  • Proceedings SIBGRAPI'98. International Symposium on Computer Graphics, Image Processing, and Vision (Cat. No.98EX237)

    Publication Year: 1998
    Request permission for commercial reuse | PDF file iconPDF (280 KB)
    Freely Available from IEEE
  • Stroking discrete polynomial Bezier curves via point containment paradigm

    Publication Year: 1998, Page(s):94 - 101
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (235 KB)

    The point containment predicate which specifies if a point is part of a mathematically defined shape or not is a crucial problem in computer graphics. This paper presents a stroking technique that counteracts the main disadvantage of point containment algorithms: their quadratic time complexity with increasing resolution. It is also presented an efficient algorithm to perform simultaneously the fi... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Index of authors

    Publication Year: 1998, Page(s):485 - 486
    Request permission for commercial reuse | PDF file iconPDF (220 KB)
    Freely Available from IEEE
  • Towards perception driven visualization

    Publication Year: 1998, Page(s):127 - 134
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (416 KB)

    The use of computer graphics techniques in visualization is hampered by the complexity of data, display limitations and the difficult process of establishing adequate mappings. One way to compensate for the difficulties in handling data and image complexity is to turn to users' capabilities and human factors, and to revisit visualization and interaction techniques under such premises. This paper d... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Density estimation for MR image elastic matching

    Publication Year: 1998, Page(s):320 - 325
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (120 KB)

    The problem of matching two images can be posed as finding a displacement field which assigns each point of the reference image to a point in the test image. In this paper we present an iterative algorithm to estimate the probability density function relating the intensity distribution of two MR scanners, based on the topological constraints embedded in the elastic matching model. The set of image... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Virtual seismic interpretation

    Publication Year: 1998, Page(s):119 - 126
    Cited by:  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (424 KB)

    This paper presents an application of the virtual reality paradigm to scientific visualization. We describe how the seismic interpretation task performed in oil and gas companies can be facilitated by using immersion techniques inherent to virtual reality. The feeling of immersion allows an easier and better understanding and manipulation of the three-dimensional data associated with seismic inter... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Human frequency response functions of harmonic 2, 4, 8 and 16 cycle angular frequency filters

    Publication Year: 1998, Page(s):312 - 319
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (984 KB)

    We measured narrow-band human frequency response functions for four harmonic angular frequency filters whose test frequencies were centered at either 2, 4, 8 or 16 cycles using a supra-threshold summation method. The four filter response functions of 17 experimental conditions (each) were measured eight to nine times among five observers (NAS, MMM, ERB, MC and TPL). The results show that, for the ... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Straight-line removal in boron carbide microscopic images

    Publication Year: 1998, Page(s):462 - 467
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (148 KB)

    Boron carbide microscopic images may present grains crossed by twins (or macles) viewed as straight lines in the inner part of each grain. The twins preclude the segmentation because they are very similar to the grain borders. To eliminate the twins a preprocessing step, which relies on mathematical morphology tools, is applied to the image. The main operation used is a directional opening, using ... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Cache management for real time visualization of 2D data sets

    Publication Year: 1998, Page(s):111 - 118
    Cited by:  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (192 KB)

    We present a general cache management algorithm with data pre-loading that optimizes access to data in real-time applications. We show that our algorithm provides the optimum results when the visualization sequence is known. We also present an oracle that estimates the visualization sequence for 2D data sets, and show the results of the algorithm in a virtual panorama viewer View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Adaptive speckle MAP filtering for SAR images using statistical clustering

    Publication Year: 1998, Page(s):303 - 310
    Cited by:  Papers (2)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1424 KB)

    This paper presents a nonlinear adaptive filter based on the the maximum a posteriori (MAP) approach to reduce speckle in one-look, linear detected SAR images. The k-means clustering algorithm is combined with the MAP filter in order to cluster pixels with similar statistics (Changle Li's variance ratio). Assigned to each cluster there is a window size which is used to estimate the filter paramete... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Load balancing for distributed virtual reality systems

    Publication Year: 1998, Page(s):158 - 165
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1560 KB)

    Due to the concentration of users in certain regions of the virtual world, distributed virtual reality systems-DVRS-may become unbalanced, resulting in low performance and bad utilization of system resources. The authors studied this problem and proposed a queueing model and load balancing algorithms to reduce these effects. Some experiments showed how the utilization and response time of the syst... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A constraint-based algorithm for engineering design

    Publication Year: 1998, Page(s):102 - 109
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (460 KB)

    The main focus of this work is on the development of incremental graph-based techniques for satisfying a coupled set of engineering and geometric constraints. The objective is to speed up a constraint-based design. A prototype constraint-based system has been developed to demonstrate the feasibility of these incremental algorithms. The proposed techniques were applied to the internal-combustion en... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Automatic absolute orientation of scanned aerial photographs

    Publication Year: 1998, Page(s):295 - 302
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (144 KB)

    Image orientation is a basic problem in digital photogrammetry. While interior and relative orientations were successfully automated, the same can not be said about absolute orientation. This process can be automated by using an approach based on relational matching and a heuristic that uses the analytical relation between straight features in the object space and its homologous in the image space... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A unified geometric model for 3D confocal image analysis in cytology

    Publication Year: 1998, Page(s):69 - 76
    Cited by:  Papers (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1968 KB)

    In this paper, we use partial differential equation based analysis as a methodology for computer-aided cytology. We wish to accurately extract and classify the shapes of nuclei from noisy confocal microscopy images. This is a prerequisite to an accurate quantitative intranuclear (genotypic and phenotypic) and internuclear (tissue structure) analysis of cancerous and pre-cancerous specimens. We stu... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Morphological approach of handwritten word skew correction

    Publication Year: 1998, Page(s):456 - 461
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (88 KB)

    The correction of handwritten word skew is an arduous task that must be independent of due to style and writing conditions variations. We propose here a morphology-based method to detect and correct handwritten word skew in the treatment of dates written on bank checks. Our aim is to limit the number of parameters and heuristic features necessary for a good skew correction. Our approach is based o... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Sonification to support visualization tasks

    Publication Year: 1998, Page(s):150 - 157
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (412 KB)

    Computational visualization systems and techniques have improved information gathering activities and changed the ways in which science is studied. However, the complexity of the data handled by such systems has suggested the need for alternative representation and display techniques. Auditory display has been considered to be a real possibility in this area, in a field known as sonification. The ... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Visual processing throughout the visual field

    Publication Year: 1998, Page(s):2 - 9
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (64 KB)

    This paper summarizes work done in our laboratory with a special emphasis on functional aspects of the visual field. The quality of the perceived image within a visual display depends on the information available within the display itself but also on the capacity of the human visual system to process visual information. Specifically, the paper discusses work on human visual processing which deals ... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Computer vision-based navigation for autonomous blimps

    Publication Year: 1998, Page(s):287 - 294
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (244 KB)

    Autonomous dirigibles-aerial robots that are a blimp controlled by computer based on information gathered by sensors-are a new and promising research field in robotics, offering several original work opportunities. One of them is the study of visual navigation, that would allow an autonomous dirigible to follow precise trajectories based on environmental visual information imaged by on-board camer... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A graph-anisotropic approach to 3-D data segmentation

    Publication Year: 1998, Page(s):262 - 269
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (376 KB)

    In this paper, we present a general framework for the segmentation of surfaces represented by 3-D scattered data. The method we present is based on a contextual anisotropic diffusion scheme. Contextual information at each data point involves the selection of optimal directions, locally representing the shape. Over the set of points, graph based representations are well adapted to gather this kind ... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A technique for improvement of linear attenuation coefficient maps obtained by means of X-ray tomography in multiple energies

    Publication Year: 1998, Page(s):62 - 68
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (92 KB)

    This study presents a technique for quantitative enhancement of both linear attenuation coefficients and visual features of maps obtained from multiple energies using tomographic systems. The quality of images obtained by computerized X-ray tomography in multiple energies is limited due to the number of noise pixels in the images. The method developed uses enhancement techniques with adaptative fi... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Rule-based classification procedures related to the unprecisely formulated expert rules

    Publication Year: 1998, Page(s):241 - 245
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (468 KB)

    The paper is devoted to the pattern recognition procedure based on the set of expert rules with unprecisely formulated weights understood as conditional probabilities. Adopting the probabilistic model, the recognition algorithm is derived and evaluation of its probability of misclassification is given. Furthermore, the case with both expert rules and the learning set is considered. The proposed al... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Three-dimensional reconstruction and visualization of tomographic images system using frequential techniques and wavelets

    Publication Year: 1998, Page(s):38 - 45
    Cited by:  Papers (1)  |  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (128 KB)

    This paper presents a system for three-dimensional image reconstruction based on the combination of both adaptive and wavelet reconstruction methods and the use of B-wavelets function for interpolation. Results show the usefulness of the system for three-dimensional image reconstruction and also after interpolation with data obtained by X and γ-ray computerized minitomograph scanners for soi... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Visualization of geological prospecting data

    Publication Year: 1998, Page(s):142 - 149
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (404 KB)

    Oil reservoirs searching is based on several exploratory methods, which produce a large quantity of data that must be interpreted and analyzed by geologists. Graphic systems can help these tasks by providing three-dimensional representations to convey information in a more natural and efficient way to the users. Therefore, they are typical scientific visualization applications. This paper presents... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An algorithm for intersecting and trimming parametric meshes

    Publication Year: 1998, Page(s):86 - 93
    Cited by:  Patents (17)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (376 KB)

    We present an algorithm for intersecting finite-element meshes defined on parametric surface patches. The intersection curves are modeled precisely and both meshes are adjusted to the newly formed borders. The algorithm is part of an interactive shell modeling program, which has been used in the design of large offshore oil structures. We avoid unacceptable interaction delays by using a variant of... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Biased clustering methods for image classification

    Publication Year: 1998, Page(s):278 - 285
    Cited by:  Patents (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (192 KB)

    Classification of image data can be done using supervised or unsupervised methods. Each approach has advantages and disadvantages: supervised methods require labeled samples in order to create signatures or discriminating functions to classify unknown data, which at the end of the process will have class labels attached to it. Unsupervised methods, usually based on clustering, do not require sampl... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.