Friday, March 21, 2014

Gaussian Process Dynamical Models for Human Motion

Abstract


We introduce Gaussian process dynamical models (GPDMs) for nonlinear time series analysis, with applications to learning models of human pose and motion from high-dimensional motion capture data. A GPDM is a latent variable model. It comprises a low dimensional latent space with associated dynamics, as well as a map from the latent space to an observation space. We marginalize out the model parameters in closed form by using Gaussian process priors for both the dynamical and the observation mappings. This results in a nonparametric model for dynamical systems that accounts for uncertainty in the model. We demonstrate the approach and compare four learning algorithms on human motion capture data, in which each pose is 50-dimensional. Despite the use of small data sets, the GPDM learns an effective representation of the nonlinear dynamics in these spaces.


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Papers

Wang, J. M., Fleet, D. J., Hertzmann, A. Gaussian Process Dynamical Models for Human Motion. In IEEE Transactions on Pattern Recognition and Machine Intelligence. February, 2008. pp. 283-298.
Errata: Figures 7 and 8 on page 292 are incorrectly printed, please find the corrected figures appended to the end of the pdf.
Note: Over the years, a few people have asked me about how Equation (10) is derived.

Wang, J. M., Fleet, D. J., Hertzmann, A. Gaussian Process Dynamical Models. In Proc. NIPS 2005. December, 2005. Vancouver, Canada. pp. 1441-1448. 
 

Software

A version of this work has been implemented by Neil Lawrence as an extension to his GP-LVM software packages. Visit his Gaussian process software page for downloading information.

The current version of our GPDM code, which includes code that generate HMC samples and other mocap utils, but are not nearly as organized as Neil's code.  







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