S-SEER: Selective perception in a multimodal office activity recognition system

Abstract

The computation required for sensing and processing perceptual information can impose significant burdens on personal computer systems. We explore several policies for selective perception in SEER, a multimodal system for recognizing office activity that relies on a cascade of Hidden Markov Models (HMMs) named Layered Hidden Markov Model (LHMMs). We use LHMMs to diagnose states of a user's activity based on real-time streams of evidence from video, audio and computer (keyboard and mouse) interactions. We review our efforts to employ expected-value-of-information (EVI) to limit sensing and analysis in a context-sensitive manner. We discuss an implementation of a greedy EVI analysis and compare the results of using this analysis with a heuristic sensing policy that makes observations at different frequencies. Both policies are then compared to a random perception policy, where sensors are selected at random. Finally, we discuss the sensitivity of ideal perceptual actions to preferences encoded in utility models about information value and the cost of sensing. © Springer-Verlag Berlin Heidelberg 2005.