Motion codeword generation using selective subsequence clustering for human action recognition

Abstract

The understanding of human activity is one of the key research areas in human-centered robotic applications. In this paper, we propose complexity-based motion features for recognizing human actions. Using a time-series-complexity measure, the proposed method evaluates the amount of useful information in subsequences to select meaningful temporal parts in a human motion trajectory. Based on these meaningful subsequences, motion codewords are learned using a clustering algorithm. Motion features are then generated and represented as a histogram of the motion codewords. Furthermore, we propose a multiscaled sliding window for generating motion codewords to solve the sensitivity problem of the performance to the fixed length of the sliding window. As a classification method, we employed a random forest classifier. Moreover, to validate the proposed method, we present experimental results of the proposed approach based on two open data sets: MSR Action 3D and UTKinect data sets.