Detection of unusual optical flow patterns by multilevel hidden Markov models

Utasi, Ákos and Czúni, László (2010) Detection of unusual optical flow patterns by multilevel hidden Markov models. Optical Engineering, 49 (1). ISSN 0091-3286

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Abstract

The analysis of motion information is one of the main tools for the understanding of complex behaviors in video. However, due to the quality of the optical flow of low-cost surveillance camera systems and the complexity of motion, new robust image-processing methods are required to generate reliable higher-level information. In our novel approach there is no need for tracking objects (vehicles, pedestrians) in order to recognize anomalous motion, but dense optical flow information is used to construct mixtures of Gaussians, which are analyzed temporally. We create a multilevel model, where low-level states of non-overlapping image regions are modeled by continuous hidden Markov models (HMMs). From low-level HMMs we compose high-level HMMs to analyze the occurrence of the low-level states. The processing of large numbers of data in traditional HMMs can result in a precision problem due to the multiplication of low probability values. Thus, besides introducing new motion models, we incorporate a scaling technique into the mathematical model of HMMs to avoid precision problems and to get an effective tool for the analysis of large numbers of motion vectors. We illustrate the use of our models with real-life traffic videos.

Item Type: Article
Uncontrolled Keywords: unusual event detection, mixture of Gaussians, hidden Markov models
Subjects: Q Science > QA Mathematics and Computer Science > QA75 Electronic computers. Computer science / számítástechnika, számítógéptudomány
Divisions: Distributed Events Analysis Research Laboratory
Depositing User: �kos Utasi
Date Deposited: 11 Dec 2012 16:04
Last Modified: 11 Dec 2012 16:04
URI: http://eprints.sztaki.hu/id/eprint/5720

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