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Pattern Analysis and Machine Intelligence, IEEE Transactions on

Issue 9 • Date Sep 1992

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Displaying Results 1 - 9 of 9
  • Bayesian estimation of motion vector fields

    Publication Year: 1992 , Page(s): 910 - 927
    Cited by:  Papers (120)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1840 KB)  

    A stochastic approach to the estimation of 2D motion vector fields from time-varying images is presented. The formulation involves the specification of a deterministic structural model along with stochastic observation and motion field models. Two motion models are proposed: a globally smooth model based on vector Markov random fields and a piecewise smooth model derived from coupled vector-binary Markov random fields. Two estimation criteria are studied. In the maximum a posteriori probability (MAP) estimation, the a posteriori probability of motion given data is maximized, whereas in the minimum expected cost (MEC) estimation, the expectation of a certain cost function is minimized. Both algorithms generate sample fields by means of stochastic relaxation implemented via the Gibbs sampler. Two versions are developed: one for a discrete state space and the other for a continuous state space. The MAP estimation is incorporated into a hierarchical environment to deal efficiently with large displacements View full abstract»

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  • 3-D reconstruction using mirror images based on a plane symmetry recovering method

    Publication Year: 1992 , Page(s): 941 - 946
    Cited by:  Papers (21)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (416 KB)  

    Three-dimensional reconstruction from a perspective 2D image using mirrors is addressed. The mirrors are used to form symmetrical relations between the direct image and mirror images. By finding correspondences between them, the 3D shape can be reconstructed by means of plane symmetry recovering method using the vanishing point. Two constraints are used in determining the correspondence. In the case where only one mirror is used, invisible parts both in the direct image and in the mirror image may still remain. Using multiple mirrors, however, occluded parts will decrease or disappear, and occlusion-free object reconstruction becomes possible View full abstract»

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  • Knowledge-directed interpretation of mechanical engineering drawings

    Publication Year: 1992 , Page(s): 928 - 940
    Cited by:  Papers (35)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1320 KB)  

    A methodology for the interpretation of images of engineering drawings is presented. The approach is based on the combination of schemata describing prototypical drawing constructs with a library of low-level image analysis routines and a set of explicit control rules applied by an LR(1) parser. The resulting system (Anon) integrates bottom-up and top-down processing strategies within a single, flexible framework modeled on the human perceptual cycle. Anon's structure and operation are described and discussed, and examples of its interpretation of real mechanical drawings are shown View full abstract»

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  • Object delineation in noisy images by a modified policy-iteration method

    Publication Year: 1992 , Page(s): 952 - 958
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (600 KB)  

    The contours of isolated objects in noisy images may be detected with a minimal cost contour detection algorithm. An algorithm that is based on the policy-iteration method for locating the closed minimal cost path is introduced. Computational results indicate that it is computationally more efficient than the dynamic programming approach. The method is applied to left ventricular contours in scintigraphic images, although it is applicable to any domain where a closed minimal cost path is to be computed in a matrix of cost coefficients View full abstract»

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  • Optimal visual motion estimation: a note

    Publication Year: 1992 , Page(s): 959 - 964
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (484 KB)  

    The problem of estimating 3D motion in an optimal manner using correspondences of features in two views is analyzed. The importance of having an optimal estimator is twofold: first, for the estimation itself and, second, for the bound it offers on how much sensitivity one can expect from a two-frame, point-based motion algorithm. The optimal estimator turns out to be nonlinear, and for that reason, techniques that provide very good initial guesses for the iterative computation of the optimal estimator are developed View full abstract»

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  • Hierarchical contour-based segmentation of dynamic scenes

    Publication Year: 1992 , Page(s): 946 - 952
    Cited by:  Papers (2)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (692 KB)  

    A motion segmentation algorithm is introduced. The algorithm is based on the assumption of one coherent moving area (without holes) on a static background. It does coarse-to-fine pyramid-based boundary refinement that attempts to classify the blocks into three classes: inside, border, and outside View full abstract»

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  • Viewpoint invariant recovery of visual surfaces from sparse data

    Publication Year: 1992 , Page(s): 897 - 909
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1260 KB)  

    An algorithm for the reconstruction of visual surfaces from sparse data is proposed. An important aspect of this algorithm is that the surface estimated from the sparse data is approximately invariant with respect to rigid transformation of the surface in 3D space. The algorithm is based on casting the problem as an ill-posed inverse problem that must be stabilized using a priori information related to the image and constraint formation. To form a surface estimate that is approximately invariant with respect to viewpoint, the stabilizing information is based on invariant surface characteristics. With appropriate approximations, this results in a convex functional to minimize, which is then solved using finite element analysis. The relationship of this algorithm to several previously proposed reconstruction algorithms is discussed, and several examples that demonstrate its effectiveness in reconstructing viewpoint-invariant surface estimates are given View full abstract»

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  • A three-frame algorithm for estimating two-component image motion

    Publication Year: 1992 , Page(s): 886 - 896
    Cited by:  Papers (101)  |  Patents (29)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1064 KB)  

    A fundamental assumption made in formulating optical-flow algorithms, that motion at any point in an image can be represented as a single pattern component undergoing a simple translation, fails for a number of situations that commonly occur in real-world images. An alternative formulation of the local motion assumption in which there may be two distinct patterns undergoing coherent (e.g. affine) motion within a given local analysis region is proposed. An algorithm for the analysis of two-component motion in which tracking and nulling mechanisms applied to three consecutive image frames separate and estimate the individual components is given. Precise results are obtained, even for components that differ only slightly in velocity as well as for a faint component in the presence of a dominant, masking component. The algorithm provides precise motion estimates for a set of elementary two-motion configurations and is robust in the presence of noise View full abstract»

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  • Thinning methodologies-a comprehensive survey

    Publication Year: 1992 , Page(s): 869 - 885
    Cited by:  Papers (257)  |  Patents (16)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1780 KB)  

    A comprehensive survey of thinning methodologies is presented. A wide range of thinning algorithms, including iterative deletion of pixels and nonpixel-based methods, is covered. Skeletonization algorithms based on medial axis and other distance transforms are not considered. An overview of the iterative thinning process and the pixel-deletion criteria needed to preserve the connectivity of the image pattern is given first. Thinning algorithms are then considered in terms of these criteria and their modes of operation. Nonpixel-based methods that usually produce a center line of the pattern directly in one pass without examining all the individual pixels are discussed. The algorithms are considered in great detail and scope, and the relationships among them are explored View full abstract»

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The IEEE Transactions on Pattern Analysis and Machine Intelligence (TPAMI) is published monthly. Its editorial board strives to present most important research results in areas within TPAMI's scope.

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David A. Forsyth
University of Illinois