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ANSIG An Analytic Signature for ANSIG An Analytic Signature for Permutation Invariant 2D Shape Representation José Jerónimo Moreira Rodrigues
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ANSIG Outline Motivation: shape representation Permutation invariance: ANSIG Dealing with geometric transformations Experiments Conclusion Real-life demonstration
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ANSIG MotivationANSIG Geometric transformations ExperimentsConclusion Real-life demonstration Motivation The Permutation Problem
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ANSIG MotivationANSIG Geometric transformations ExperimentsConclusion Real-life demonstration Shape diversity
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ANSIG MotivationANSIG Geometric transformations ExperimentsConclusion Real-life demonstration When the labels are known: Kendall’s shape ‘Shape’ is the geometrical information that remains when location/scale/rotation effects are removed. Limitation: points must have labels, i.e., vectors must be ordered, i.e., correspondences must be known
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ANSIG MotivationANSIG Geometric transformations ExperimentsConclusion Real-life demonstration Without labels: the permutation problem permutation matrix
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ANSIG MotivationANSIG Geometric transformations ExperimentsConclusion Real-life demonstration Our approach: seek permutation invariant representations
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Motivation ANSIG ANSIG Geometric transformations ExperimentsConclusion Real-life demonstration ANSIG
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Motivation ANSIG ANSIG Geometric transformations ExperimentsConclusion Real-life demonstration The analytic signature (ANSIG) of a shape
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Motivation ANSIG ANSIG Geometric transformations ExperimentsConclusion Real-life demonstration Maximal invariance of ANSIG same signature equal shapes
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Motivation ANSIG ANSIG Geometric transformations ExperimentsConclusion Real-life demonstration Maximal invariance of ANSIG Consider, such that Since, their first nth order derivatives are equal:
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Motivation ANSIG ANSIG Geometric transformations ExperimentsConclusion Real-life demonstration Maximal invariance of ANSIG This set of equalities implies that - Newton’s identities The derivatives are the moments of the zeros of the polynomials
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Motivation ANSIG ANSIG Geometric transformations ExperimentsConclusion Real-life demonstration Storing ANSIGs The ANSIG maps to an analytic function How to store an ANSIG?
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Motivation ANSIG ANSIG Geometric transformations ExperimentsConclusion Real-life demonstration Storing ANSIGs 2) Approximated by uniform sampling: 1) Cauchy representation formula: 512
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ANSIG Motivation Geometric transformations ExperimentsConclusion Real-life demonstration ANSIG Geometrictransformations
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ANSIG Motivation Geometric transformations ExperimentsConclusion Real-life demonstration ANSIG (Maximal) Invariance to translation and scale Remove mean and normalize scale:
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ANSIG Motivation Geometric transformations ExperimentsConclusion Real-life demonstration ANSIG Sampling density
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ANSIG Motivation Geometric transformations ExperimentsConclusion Real-life demonstration ANSIG Shape rotation: circular-shift of ANSIG Rotation
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ANSIG Motivation Geometric transformations ExperimentsConclusion Real-life demonstration ANSIG Efficient computation of rotation Solution: maximum of correlation. Using FFTs, “time” domain frequency domain Optimization problem:
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ANSIG Motivation Geometric transformations ExperimentsConclusion Real-life demonstration ANSIG Shape-based classification SHAPE TO CLASSIFY SHAPE 3 SHAPE 2 SHAPE 1 MÁXMÁX Similarity SHAPE2SHAPE2 DATABASE
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ANSIG Motivation Geometric transformations ExperimentsConclusion Real-life demonstration ANSIG Experiments
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ANSIG Motivation Geometric transformations ExperimentsConclusion Real-life demonstration ANSIG MPEG7 database (216 shapes)
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ANSIG Motivation Geometric transformations ExperimentsConclusion Real-life demonstration ANSIG Automatic trademark retrieval
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ANSIG Motivation Geometric transformations ExperimentsConclusion Real-life demonstration ANSIG Robustness to model violation
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ANSIG Motivation Geometric transformations ExperimentsConclusion Real-life demonstration ANSIG Object recognition
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ANSIG Motivation Geometric transformations ExperimentsConclusion Real-life demonstration ANSIG Conclusion
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ANSIG Motivation Geometric transformations ExperimentsConclusion Real-life demonstration ANSIG Summary and conclusion ANSIG: novel 2D-shape representation - Maximally invariant to permutation (and scale, translation) - Deals with rotations and very different number of points - Robust to noise and model violations Relevant for several applications Development of software packages for demonstration Publications: - IEEE CVPR 2008 - IEEE ICIP 2008 - Submitted to IEEE Transactions on PAMI
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ANSIG Motivation Geometric transformations ExperimentsConclusion Real-life demonstration ANSIG Future developments Different sampling schemes More than one ANSIG per shape class Incomplete shapes, i.e., shape parts Analytic functions for 3D shape representation
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ANSIG Motivation Geometric transformations ExperimentsConclusion Real-life demonstration ANSIG Real-lifedemonstration
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ANSIG Motivation Geometric transformations ExperimentsConclusion Real-life demonstration ANSIG Shape-based image classfication Shape database Pre-processing: morphological filter operations, segmentation, etc. Image acquisition system Shape-based classification
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