A new probabilistic model for recognizing signs with systematic modulations

Abstract

This paper addresses an aspect of sign language (SL) recognition that has largely been overlooked in previous work and yet is integral to signed communication. It is the most comprehensive work to-date on recognizing complex variations in sign appearances due to grammatical processes (inflections) which systematically modulate the temporal and spatial dimensions of a root sign word to convey information in addition to lexical meaning. We propose a novel dynamic Bayesian network the Multichannel Hierarchical Hidden Markov Model (MH-HMM)- as a modelling and recognition framework for continuously signed sentences that include modulated signs. This models the hierarchical, sequential and parallel organization in signing while requiring synchronization between parallel data streams at sign boundaries. Experimental results using particle filtering for decoding demonstrate the feasibility of using the MH-HMM for recognizing inflected signs in continuous sentences. © Springer-Verlag Berlin Heidelberg 2007.