Semi-Supervised Adapted HMMs for Unusual Event Detection

  • Authors:

  • Dong Zhang;Daniel Gatica-Perez;Samy Bengio;Iain McCowan

  • Affiliations:

  • IDIAP Research Institute and Swiss Federal Institute of Technology;IDIAP Research Institute;IDIAP Research Institute and Swiss Federal Institute of Technology;IDIAP Research Institute

  • Venue:
  • CVPR '05 Proceedings of the 2005 IEEE Computer Society Conference on Computer Vision and Pattern Recognition (CVPR'05) - Volume 1 - Volume 01
  • Year:
  • 2005

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Abstract

We address the problem of temporal unusual event detection. Unusual events are characterized by a number of features (rarity, unexpectedness, and relevance) that limit the application of traditional supervised model-based approaches. We propose a semi-supervised adapted Hidden Markov Model (HMM) framework, in which usual event models are first learned from a large amount of (commonly available) training data, while unusual event models are learned by Bayesian adaptation in an unsupervised manner. The proposed framework has an iterative structure, which adapts a new unusual event model at each iteration. We show that such a framework can address problems due to the scarcity of training data and the difficulty in pre-defining unusual events. Experiments on audio, visual, and audio-visual data streams illustrate its effectiveness, compared with both supervised and unsupervised baseline methods.