Recognition of Human Actions using Edit Distance on Aclet Strings

In this paper we propose a novel method for human action recognition based on string edit distance. A two layer representation is introduced in order to exploit the temporal sequence of the events: a first representation layer is obtained by using a feature vector obtained from depth images. Then, each action is represented as a sequence of symbols, where each symbol corresponding to an elementary action (aclet) is obtained according to a dictionary previously defined during the learning phase. The similarity between two actions is finally computed in terms of string edit distance, which allows the system to deal with actions showing different length as well as different temporal scales. The experimentation has been carried out on two widely adopted datasets, namely the MIVIA and the MHAD datasets, and the obtained results, compared with state of the art approaches, confirm the effectiveness of the proposed method.