Abstract: Level set algorithm is an effectual algorithm when tracking the nonrigid moving targets on complicated condilions. An adaptive algorithm was proposed to solve the initialization problem of level set. Firstly, the particle filter algorithm was used to track the targets, and the rough external contour could be gotten. Then based on the centroid of the external contour,the level set curve evolution was performed to get the precise external contour of the targets,and the extract results were fed back to the tracking frame; lastly the likelihood function was improved by updating the reference template dynamically. hhe experiment results show that the algorithm proposed in this paper can adapt to the moving changes of the nonrigid targets,and the targets can be tracked accurately.

Key words: Particle filter, Level set, Moving targets tracking, Initialization