A Multi-scale Generative Model for Animate Shapes and Parts

  • Authors:
  • Aleksandr Dubinskiy;Song Chun Zhu

  • Affiliations:
  • -;-

  • Venue:
  • ICCV '03 Proceedings of the Ninth IEEE International Conference on Computer Vision - Volume 2
  • Year:
  • 2003

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Abstract

This paper presents a multi-scale generative model for representinganimate shapes and extracting meaningful parts of objects. Themodel assumes that animate shapes (2D simple closed curves) areformed by a linear superposition of a number of shape bases. Theseshapebases resemble the multi-scale Gabor bases in image pyramidrepresentation, are well localized in both spatial and frequencydomains, and form an over-complete dictionary. This model issimpler than the popular B-spline representation since it does notengage a domainpartition. Thus it eliminates the interferencebetween adjacent B-spline bases, and becomes a true linear additivemodel. We pursue the bases by reconstructing the shape in acoarse-to-fine procedure through curve evolution. These shape basesare further organized ina tree-structure where the bases in eachsubtree sum up to an intuitive part of the object. To buildprobabilistic model for a class of objects, we propose a Markovrandom field model at each level of the tree representation toaccount for the spatial relationship between bases. Thus the finalmodel integrates a Markov tree (generative) model over scales and aMarkov random field over space. We adopt EM-type algorithm forlearning the meaningful parts for a shape class, and show someresults on shape synthesis.