Abstract
This paper presents a new critical event detection method simplified for an embedded appliance mounted on an elevator car. We first define that the critical event is unusual action such as violent action, counteraction, etc, and introduce the violent action degree(VAD). We use an optical flow based method to analyze the current state of the motion through an ITV(Industrial Television) camera. After motion analysis, we calculate a normalized statistical value, which is the VAD. The statistical value is the multiple of the optical flow direction variance, the optical flow magnitude variance, and optical flow area. Our method calculates the statistical value variance and normalize it by the variance. At last we can detect critical event by thresholding the VAD. In addition, we should detect persons and objects staying in an elevator for a long time. For this purpose, we apply texture background subtraction method. Our violent action detection method detects 80% of critical events where at most 6% of false acception and object detection method detects 99% where about 1% of false acception.
