Abstract: In the case of smoke generated in the early stage of the fire，the video captured by the fixed
monitoring probe is used to detect the fire smoke，and the frame difference method of the computer video
detection technology is used to obtain the area of the smoke movement． When the camera is not moving，two
consecutive images are obtained and the motion region in the video is detected． The video of the smoke is
segmented by the variational level set method，and the motion region is segmented from the background to detect
and analyze the smoke． Therefore，it is more accurate to judge the fire through the smoke，and the detection
result is more real-time，which improves the efficiency of the video command fire fighting work．

Key words: video detection, variational level set, optical flow method, frame difference method, Chan-Vese model, video segmentation