An Active Tracking Method for Small Ships in Open Water Based on Fixed/PTZ Camera System
It is difficult to actively track and capture clear images of inland river ships with the current Closed Cir-cuit Television(CCTV)system.To fill the gap,an active tracking method for small ships in open waters based on the fixed/pan-tilt-zoom(PTZ)camera system is proposed.A three-layer joint calibration model based on a virtual quadrilateral(VQ)is introduced to jointly calibrate the fixed camera and the PTZ camera,which matches the image coordinate with the pan and tilt angle of the PTZ camera one by one;The introduced VQ filters out the targets out-side the quadrilateral,eliminating inference and improving the accuracy of detection.The mapping relationship be-tween the image coordinates and the world coordinates can be obtained by using the Perspective-n-Point(PnP)algo-rithm and the vertices of the VQ;Fourthly,the world coordinates of the points in the VQ are transformed into the Pan-Tilt-Hight(PTH)coordinates via PTH model.Then,by calculating the coordinate of the ship(the centroid of the ship)in the VQ,the pan and tilt angle of the PTZ camera can be derived,achieving real-time active tracking and keeping the target at the center of the PTZ camera image.To validate the proposed method,two real scenes are intro-duced,namely Chunhui Lake in Xiaogan City and the Sino-French Bridge section of the Han River in Wuhan City,Hubei Province.The results indicate that,①the F1-Scores of the proposed method on the fixed camera are 96.82% and 97.62%,respectively;② when the proposed method is applied to the PTZ camera for tracking the moving ships,the failure rate is 4.63% .In summary,the proposed active tracking method performs reasonably in practice with a high tracking rate of 18.55 fps.
万方数据
维普
