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Modeling Complex Temporal Composition of Actionlets for Activity Prediction
Kang Li1, Jie Hu2, and Yun Fu1
1Department of ECE and College of CIS, Northeastern University, Boston, MA, USA
kongkong115@gmail.com
y.fu@neu.edu
2Department of CSE, State University of New York, Buffalo, NY, USA
jhu6@buffalo.edu
Abstract. Early prediction of ongoing activity has been more and more valuable in a large variety of time-critical applications. To build an effective representation for prediction, human activities can be characterized by a complex temporal composition of constituent simple actions. Different from early recognition on short-duration simple activities, we propose a novel framework for long-duration complex activity prediction by discovering the causal relationships between constituent actions and the predictable characteristics of activities. The major contributions of our work include: (1) we propose a novel activity decomposition method by monitoring motion velocity which encodes a temporal decomposition of long activities into a sequence of meaningful action units; (2) Probabilistic Suffix Tree (PST) is introduced to represent both large and small order Markov dependencies between action units; (3) we present a Predictive Accumulative Function (PAF) to depict the predictability of each kind of activity. The effectiveness of the proposed method is evaluated on two experimental scenarios: activities with middle-level complexity and activities with high-level complexity. Our method achieves promising results and can predict global activity classes and local action units.
LNCS 7572, p. 286 ff.
lncs@springer.com
© Springer-Verlag Berlin Heidelberg 2012