CSAIL Event Calendar: Previous Series

On the Local form and transitions of the shock graph for object recognition

Speaker: Benjamin B. Kimia , Division of Engineering, Brown University
Date: April 21 2004
Time: 2:00PM to 3:00PM
Location: 32-D507
Host: Greg Shakhnarovich, CSAIL

Contact: Greg Shakhnarovich, gregory@ai.mti.edu
Relevant URL:

ABSTRACT:

The use of a suitable shape representation is critical for a number of
visual tasks. We describe how the shock graph, a dynamic hierarchical
representation of the medial axis, is used for object recognition from
silhouettes. Our approach is based on capturing the topology of the shape space
via a dis-similarity metric that is the cost of the optimal deformation
path between two shapes. Since the space of deformation paths is
infinite-dimensional we discretize it by defining equivalence classes
based on the shock graph topology and its transitions, which are
related to the classical instabilities of the medical axis. A formal
analysis of the local form of the shock graph and its transitions under
a one-parameter family of deformations is described. The
transition-based description of deformation paths is then searched
under an edit-distance paradigm to find the optimal path. We describe
recognition results which are stable under a range of visual
transformations and which for several databases of up to 1032 shapes
recover the correct category.

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