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40
Modelbased tracking of selfoccluding articulated objects
 In ICCV
, 1995
"... Computer sensing of hand and limb motion is an important problem for applications in humancomputer interaction and computer graphics. We describe aframework for local tracking of selfoccluding motion, in which one part of an object obstructs the visibility of another. Our approach uses a kinematic ..."
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Cited by 205 (7 self)
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Computer sensing of hand and limb motion is an important problem for applications in humancomputer interaction and computer graphics. We describe aframework for local tracking of selfoccluding motion, in which one part of an object obstructs the visibility of another. Our approach uses a kinematic model to predict occlusions and windowed templates to track partially occluded objects. We present oline 3D tracking results for hand motion with signi cant selfocclusion. 1
Stochastic Completion Fields: A Neural Model of Illusory Contour Shape and Salience
 Neural Computation
, 1995
"... We describe an algorithm and representation level theory of illusory contour shape and salience. Unlike previous theories, our model is derived from a single assumption namely, that the prior probability distribution of boundary completion shape can be modeled by a random walk in a lattice whose ..."
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Cited by 177 (14 self)
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We describe an algorithm and representation level theory of illusory contour shape and salience. Unlike previous theories, our model is derived from a single assumption namely, that the prior probability distribution of boundary completion shape can be modeled by a random walk in a lattice whose points are positions and orientations in the image plane (i.e., the space which one can reasonably assume is represented by neurons of the mammalian visual cortex). Our model does not employ numerical relaxation or other explicit minimization, but instead relies on the fact that the probability that a particle following a random walk will pass through a given position and orientation on a path joining two boundary fragments can be computed directly as the product of two vectorfield convolutions. We show that for the random walk we define, the maximum likelihood paths are curves of least energy, that is, on average, random walks follow paths commonly assumed to model the shape of illusory co...
Mixture Models for Optical Flow Computation
, 1993
"... The computahon of optical flow rehes on merg. ,ng znformat,on avadable over an zmage patch to form an estimate of D mage veloct!t at a point. Ths merging process rases a host of ssues, which include the treatment of outhers m component ve !oc*t!t measurements and the modehng of mulhple motions wath ..."
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Cited by 146 (16 self)
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The computahon of optical flow rehes on merg. ,ng znformat,on avadable over an zmage patch to form an estimate of D mage veloct!t at a point. Ths merging process rases a host of ssues, which include the treatment of outhers m component ve !oc*t!t measurements and the modehng of mulhple motions wathm a patch whzch arse from occlusion boundaries or transparency. We present a new ap proach for deahno wth these ssues. which s based Proc. CVPR'93, New York, June 1993 2 a c Figure 2: Multiple motion constraint lines for the region in Figure I (see text).
Cooperative Robust Estimation Using Layers of Support
 IEEE Transactions on Pattern Analysis and Machine Intelligence
, 1991
"... We present an approach to the problem of representing images that contain multiple objects or surfaces. Rather than use an edgebased approach to represent the segmentation of a scene, we propose a multilayer estimation framework which uses support maps to represent the segmentation of the image in ..."
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Cited by 86 (5 self)
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We present an approach to the problem of representing images that contain multiple objects or surfaces. Rather than use an edgebased approach to represent the segmentation of a scene, we propose a multilayer estimation framework which uses support maps to represent the segmentation of the image into homogeneous chunks. This supportbased approach can represent objects that are split into disjoint regions, or have surfaces that are transparently interleaved. Our framework is based on an extension of robust estimation methods which provide a theoretical basis for supportbased estimation. The Minimum Description Length principle is used to decide how many support maps to use in describing a particular image. We show results applying this framework to heterogeneous interpolation and segmentation tasks on range and motion imagery. 1 Introduction Realworld perceptual systems must deal with complicated and cluttered environments. To succeed in such environments, a system must be able to r...
A Bayesian treatment of the stereo correspondence problem using halfoccluded regions
, 1991
"... A halfoccluded region in a stereo pair is a set of pixels in one image representing points in svace visible to that camera or eye only, and not to ihe other. These occur typically as parts of the background immediately to the left and right sides of nearby occluding objects, and are present in most ..."
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Cited by 75 (6 self)
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A halfoccluded region in a stereo pair is a set of pixels in one image representing points in svace visible to that camera or eye only, and not to ihe other. These occur typically as parts of the background immediately to the left and right sides of nearby occluding objects, and are present in most natural scenes. Previous approaches to stereo either ignored these unmatchable points or attempted to weed them out in a second pass. Our algorithm incorporates them from the start as a strong clue to depth discontinuities. Psychophysical evidence suggests that the human visual system also exploits these clues. We start by deriving a measure for goodness of fit and a prior based on a simplified model of objects in space, which leads to an energy functional depending both on the depth as measured from a central “cyclopean ” eye and on the regions of points occluded from the left and right eye perspectives. We minimize this using dynamic programming along epipolar lines followed by annealing in both dimensions. Experiments indicate that this method is very effective even in difficult scenes. 1
Topographic Maps and Local Contrast Changes in Natural Images
 Int. J. Comp. Vision
, 1999
"... . We call "natural" image any photograph of an outdoor or indoor scene taken by a standard camera. We discuss the physical generation process of natural images as a combination of occlusions, transparencies and contrast changes. This description fits to the phenomenological description of Gaetano Ka ..."
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Cited by 51 (8 self)
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. We call "natural" image any photograph of an outdoor or indoor scene taken by a standard camera. We discuss the physical generation process of natural images as a combination of occlusions, transparencies and contrast changes. This description fits to the phenomenological description of Gaetano Kanizsa according to which visual perception tends to remain stable with respect to these basic operations. We define a contrast invariant presentation of the digital image, the topographic map, where the subjacent occlusiontransparency structure is put into evidence by the interplay of level lines. We prove that each topographic map represents a class of images invariant with respect to local contrast changes. Several visualization strategies of the topographic map are proposed and implemented and mathematical arguments are developed to establish stability properties of the topographic map under digitization. Keywords: topographic map, mathematical morphology, level set, junctions, contrast changes, digitization 1.
Perceptual Completion of Occluded Surfaces
, 1994
"... Researchers in computer vision have primarily studied the problem of visual reconstruction of environmental structure that is plainly visible. In this thesis, the conventional goals of visual reconstruction are generalized to include both visible and occluded forward facing surfaces. This larger f ..."
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Cited by 31 (5 self)
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Researchers in computer vision have primarily studied the problem of visual reconstruction of environmental structure that is plainly visible. In this thesis, the conventional goals of visual reconstruction are generalized to include both visible and occluded forward facing surfaces. This larger fraction of the environment is termed the anterior surfaces. Because multiple anterior surface neighborhoods project onto a single image neighborhood wherever surfaces overlap, surface neighborhoods and image neighborhoods are not guaranteed to be in onetoone correspondence, as conventional "shapefrom" methods assume. The result is that the topology of threedimensional scene structure can no longer be taken for granted, but must be inferred from evidence...
Connected Components of Sets of Finite Perimeter and Applications to Image Processing
 JOURNAL OF THE EUROPEAN MATHEMATICAL SOCIETY
, 1999
"... This paper contains a systematic analysis of a natural measure theoretic notion of connectedness for sets of finite perimeter in R^N, introduced by H. Federer in the more general framework of the theory of currents. We provide a new and simpler proof of the existence and uniqueness of the decomposit ..."
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Cited by 21 (7 self)
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This paper contains a systematic analysis of a natural measure theoretic notion of connectedness for sets of finite perimeter in R^N, introduced by H. Federer in the more general framework of the theory of currents. We provide a new and simpler proof of the existence and uniqueness of the decomposition into the socalled Mconnected components. Moreover, we study carefully the structure of the essential boundary of these components and give in particular a reconstruction formula of a set of finite perimeter from the family of the boundaries of its components. In the two dimensional case we show that this notion of connectedness is comparable with the topological one, modulo the choice of a suitable representative in the equivalence class. Our strong motivation for this study is a mathematical justification of all those operations in image processing that involve connectedness and boundaries. As an application, we use this weak notion of connectedness to provide a rigorous mathemati...