Classification of dynamics on Riemannian manifold

Title:
Classification of dynamics on Riemannian manifold
Creator:
Zhang, Xikang (Author)
Contributor:
Sznaier, Mario (Advisor)
Camps, Octavia (Committee member)
Dy, Jennifer (Committee member)
Ioannidis, Stratis (Committee member)
Language:
English
Publisher:
Boston, Massachusetts : Northeastern University, May 2018
Date Awarded:
May 2018
Date Accepted:
April 2018
Type of resource:
Text
Genre:
Dissertations
Format:
electronic
Digital origin:
born digital
Abstract/Description:
Comparison and classification of temporal sequences is a key problem in action recognition, event detection and abnormal activity detection. The current methods either fail to model the dynamics of the data or suffer from high computational cost. We propose a new framework to compare temporal sequences. The proposed approach captures the underlying dynamics of the data while avoiding expensive estimation procedures, making it suitable to process large numbers of sequences.

For simple dynamical sequences, we embed the sequences into a Riemannian manifold by using positive definite regularized Gram matrices of their Hankelets. It captures better the underlying geometry than directly comparing the sequences or their Hankel matrices. Moreover, Gram matrices inherit desirable properties from the underlying Hankel matrices: their rank measures the complexity of the underlying dynamics, and the order and the coefficients of the associated regressive models are invariant to affine transformations and varying initial conditions.

For complex temporal sequences that contain dynamics switches, we consider the problem of switched Wiener system identification from a Kernel based manifold embedding perspective. We show that a computationally efficient solution can be obtained using a polynomial optimization approach that allows for exploiting the underlying sparse structure of the problem and provides optimality certificates. As an alternative, we provide a low complexity algorithm for the case where the affine part of the system switches only between two sub models.

The benefits of this framework are illustrated using both academic examples and real data examples in system identification, action recognition, activity segmentation and multi-camera motion segmentation.
Subjects and keywords:
dynamics
efficient
embedding
motion segmentation
Riemannian manifold
switched system identification
DOI:
https://doi.org/10.17760/D20290581
Permanent Link:
http://hdl.handle.net/2047/D20290581
Use and reproduction:
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