Incremental Learning in Human Action Recognition Based on Snippets

In this paper, we present a systematic framework for recognizing human actions without relying on impractical assumptions, such as processing of an entire video or requiring a large look-ahead of frames to label an incoming video. As a secondary goal, we examine incremental learning as an overlooked obstruction to the implementation of reliable real-time recognition. Assuming weak appearance constancy, the shape of an actor is approximated by adaptively changing intensity histograms to extract pyramid histograms of oriented gradient features. As action progresses, the shape update is carried out by adjustment of a few blocks within a tracking window to closely track evolving contours. The nonlinear dynamics of an action are learned using a recursive analytic approach, which transforms training into a simple linear representation. Such a learning strategy has two advantages: 1) minimized error rates, and significant savings in computational time; and 2) elimination of the widely accepted limitations of batch-mode training for action recognition. The effectiveness of our proposed framework is corroborated by experimental validation against the state of the art.