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21
Flexible Syntactic Matching of Curves and its Application to Automatic Hierarchical Classification of Silhouettes
 IEEE Transactions on Pattern Analysis and Machine Intelligence
"... Curve matching is one instance of the fundamental correspondence problem. Our exible algorithm is designed to match curves under substantial deformations and arbitrary large scaling and rigid transformations. A syntactic representation is constructed for both curves, and an edit transformation which ..."
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Cited by 113 (2 self)
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Curve matching is one instance of the fundamental correspondence problem. Our exible algorithm is designed to match curves under substantial deformations and arbitrary large scaling and rigid transformations. A syntactic representation is constructed for both curves, and an edit transformation which maps one curve to the other is found using dynamic programming. We present extensive...
On aligning curves
 IEEE TPAMI
, 2003
"... We present a novel approach to finding a correspondence (alignment) between two curves. The correspondence is based on a notion of an alignment curve which treats both curves symmetrically. We then define a similarity metric based on the alignment curve using two intrinsic properties of the curve, ..."
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Cited by 94 (3 self)
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We present a novel approach to finding a correspondence (alignment) between two curves. The correspondence is based on a notion of an alignment curve which treats both curves symmetrically. We then define a similarity metric based on the alignment curve using two intrinsic properties of the curve, namely, length and curvature. The optimal correspondence is found by an efficient dynamicprogramming method both for aligning pairs of curve segments and pairs of closed curves, and is effective in the presence of a variety of transformations of the curve. Finally, the correspondence is shown in application to handwritten character recognition, prototype formation, and object recognition, and is potentially useful in other applications such as registration and tracking.
Hierarchical matching of deformable shapes
 In CVPR
, 2007
"... We describe a new hierarchical representation for twodimensional objects that captures shape information at multiple levels of resolution. The representation is based on a hierarchical description of an object’s boundary, and can be used in an elastic matching framework, both for comparing pairs of ..."
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Cited by 74 (0 self)
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We describe a new hierarchical representation for twodimensional objects that captures shape information at multiple levels of resolution. The representation is based on a hierarchical description of an object’s boundary, and can be used in an elastic matching framework, both for comparing pairs of objects and for detecting objects in cluttered images. In contrast to classical elastic models, our representation explicitly captures global shape information. This leads to richer geometric models and more accurate recognition results. Our experiments demonstrate classification results that are significantly better than the current stateoftheart in several shape datasets. We also show initial experiments in matching shapes to cluttered images. 1 1.
ViewBased Object Recognition Using Saliency Maps
, 1998
"... We introduce a novel viewbased object representation, called the saliency map graph (SMG), which captures the salient regions of an object view at multiple scales using a wavelet transform. This compact representation is highly invariant to translation, rotation (image and depth), and scaling, and ..."
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Cited by 48 (8 self)
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We introduce a novel viewbased object representation, called the saliency map graph (SMG), which captures the salient regions of an object view at multiple scales using a wavelet transform. This compact representation is highly invariant to translation, rotation (image and depth), and scaling, and offers the locality of representation required for occluded object recognition. To compare two saliency map graphs, we introduce two graph similarity algorithms. The first computes the topological similarity between two SMG's, providing a coarselevel matching of two graphs. The second computes the geometrical similarity between two SMG's, providing a finelevel matching of two graphs. We test and compare these two algorithms on a large database of model object views.
Shape Retrieval Based on Dynamic Programming
 IEEE Transactions on Image Processing
, 2000
"... We propose a shape matching algorithm for deformed shapes based on dynamic programming. Our algorithm is capable of grouping together segments at Corresponding author. Current address is Faculty of Computer Science, Dalhousie University, eem@cs.dal.ca This work was supported by a grant from the Na ..."
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Cited by 30 (1 self)
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We propose a shape matching algorithm for deformed shapes based on dynamic programming. Our algorithm is capable of grouping together segments at Corresponding author. Current address is Faculty of Computer Science, Dalhousie University, eem@cs.dal.ca This work was supported by a grant from the Natural Sciences and Engineering Research Council of Canada. y This work was carriedout while the author was visiting York University. finer scales in order to come up with appropriate correspondences with segments at coarser scales. We illustrate the effectiveness of our algorithm in retrieval of shapes by content on two different twodimensional datasets, one of static hand gesture shapes and another of marine life shapes. We also demonstrate the superiority of our approach over traditional approaches to shape matching and retrieval, such as Fourier descriptors, Geometric and Sequential moments. Our evaluation is based on human relevance judgements following a well established meth...
Polygon Evolution by Vertex Deletion
 ScaleSpace Theories in Computer Vision. Proc. of Int. Conf. on ScaleSpace’99, volume LNCS 1682, Corfu
, 1999
"... Abstract. We propose a simple approach to evolution of polygonal curves that is specially designed to t discrete nature of curves in digital images. It leads to simpli cation of shape complexity withnoblurring (i.e., shape rounding) e ects and no dislocation of relevant features. Moreover, in our ap ..."
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Cited by 20 (9 self)
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Abstract. We propose a simple approach to evolution of polygonal curves that is specially designed to t discrete nature of curves in digital images. It leads to simpli cation of shape complexity withnoblurring (i.e., shape rounding) e ects and no dislocation of relevant features. Moreover, in our approach the problem to determine the size of discrete steps for numerical implementations does not occur, since our evolution method leads in a natural way to a nite number of discrete evolution steps which are just the iterations of a basic procedure of vertex deletion.
Robust contour matching via the order preserving assignment problem
 IEEE Trans. on Image Processing
, 2004
"... A common approach to determining corresponding points on two shapes is to compute the cost of each possible pairing of points and solve the assignment problem (weighted bipartite matching) for the resulting cost matrix. We consider the problem of solving for point correspondences when the shapes of ..."
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Cited by 19 (0 self)
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A common approach to determining corresponding points on two shapes is to compute the cost of each possible pairing of points and solve the assignment problem (weighted bipartite matching) for the resulting cost matrix. We consider the problem of solving for point correspondences when the shapes of interest are each defined by a single, closed contour. A modification of the standard assignment problem is proposed whereby the correspondences are required to preserve the ordering of the points induced from the shapes ’ contours. Enforcement of this constraint leads to significantly improved correspondences. Robustness with respect to outliers and shape irregularity is obtained by required only a fraction of feature points to be matched. Furthermore, the minimum matching size may be specified in advance. We present efficient dynamic programming algorithms to solve the proposed optimization problem. Experiments on the Brown and MPEG7 shape databases demonstrate the effectiveness of the proposed method relative to the standard assignment problem. 1
Subpixel Contour Matching Using Continuous Dynamic Programming
 Proc. IEEE Comput. Soc. Conf. Comput. Vision and Pattern Recogn
, 1994
"... This paper presents a subpixel contour matching algorithm using a novel dynamic programming scheme. Unlike classical dynamic programming methods, where a discrete path is searched for across a graph, our approach allows the optimal continuous path to be determined. The matching is obtained as a piec ..."
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Cited by 15 (1 self)
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This paper presents a subpixel contour matching algorithm using a novel dynamic programming scheme. Unlike classical dynamic programming methods, where a discrete path is searched for across a graph, our approach allows the optimal continuous path to be determined. The matching is obtained as a piecewise parametric fonction, and no discretization is involved, nor any parameterized deformation assumed. As a side result, a measure of the deformation of the matched contours is obtained, yielding information on the quality of the match. The algorithm has been tested with different types of images, demonstrating its ability to deal with chains of contour segments as well as chains of contour edges, since the discretization of the contours does not limit the precision of the matches anymore. 1 Introduction We address the general problem of matching continuous contours in a pair of images. We are given an image containing a set of contours defined by piecewise linear functions (e.g. obtained...
Recognition Of Handwritten Numerals Using Elastic Matching
, 1995
"... Recognition of Handwritten Numerals Using Elastic Matching Patrice Scattolin Elastic matching has been used for the recognition of handwritten characters for two decades. It is usually only used for writerdependent systems with online data. We attempt to use this method in a multiwriter environ ..."
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Cited by 10 (0 self)
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Recognition of Handwritten Numerals Using Elastic Matching Patrice Scattolin Elastic matching has been used for the recognition of handwritten characters for two decades. It is usually only used for writerdependent systems with online data. We attempt to use this method in a multiwriter environment for both online and offline recognition of handwritten numerals. By its nature, elastic matching is best suited to single writer online systems. Two challenges present themselves to attain reasonable results under these conditions. First, the algorithm must be modified to better generalize the models, to recognize a wider variety of patterns with a given number of models. Secondly the offline data is not in a suitable format as the patterns are not represented by a sequence of ordered points. We will apply two modifications to the typical elastic matching system to adapt it to the multiwriter environment and for the offline data. To process the offline data, we use a stroke recon...
Skeletal shape abstraction from examples
 IEEE Tran. on PAMI
"... andSvenJ.Dickinson,Member, IEEE Abstract—Learning a class prototype from a set of exemplars is an important challenge facing researchers in object categorization. Although the problem is receiving growing interest, most approaches assume a onetoone correspondence among local features, restricting ..."
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Cited by 9 (3 self)
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andSvenJ.Dickinson,Member, IEEE Abstract—Learning a class prototype from a set of exemplars is an important challenge facing researchers in object categorization. Although the problem is receiving growing interest, most approaches assume a onetoone correspondence among local features, restricting their ability to learn true abstractions of a shape. In this paper, we present a new technique for learning an abstract shape prototype from a set of exemplars whose features are in manytomany correspondence. Focusing on the domain of 2D shape, we represent a silhouette as a medial axis graph whose nodes correspond to “parts ” defined by medial branches and whose edges connect adjacent parts. Given a pair of medial axis graphs, we establish a manytomany correspondence between their nodes to find correspondences among articulating parts. Based on these correspondences, we recover the abstracted medial axis graph along with the positional and radial attributes associated with its nodes. We evaluate the abstracted prototypes in the context of a recognition task. Index Terms—Shape abstraction, medial axis graphs, prototype learning, manytomany graph matching. Ç 1