156 IEEE GEOSCIENCE AND REMOTE SENSING MAGAZINE MARCH 2022 10 15 20 25 AutoTrack ARCF-H 5 0 100 200 300 400 500 600 700 Frame (a) 10 15 20 25 5 100 200 300 Frame (b) 400 500 600 AutoTrack ARCF-H 10 15 20 25 5 050 100 150 Frame (c) 200 250 300 AutoTrack ARCF-H 10 15 20 25 AutoTrack ARCF-H 5 100 200 300 400 500 600 10 15 20 25 5 200 400 600 800 1,000 1,200 FrameFrame (d) (e) AutoTrack ARCF-H 10 15 20 25 5 0 200 400 600 800 1,000 1,200 1,400 1,600 Frame (f) FIGURE 10. The onboard tracking performance in terms of the CLE. The six tests [(a)-(f)] where the tracking objects are marked with red boxes contain the aforementioned common UAV tracking challenges. The satisfying CLE results displayed validate the robustness of the AutoTrack [22] and ARCF-H [24] trackers in challenging real-world UAV tracking. AutoTrack ARCF-H CLE CLE CLE CLE CLE CLE