Tracking by dynamic template: Dual update mechanism

Recently, Siamese trackers have received widespread attention for visual object tracking owing to their good balance between speed and performance. Those Siamese trackers heavily depend on target template while conventional practice fixes the template to initial frame. This strategy makes it unable to cope with variation of target appearance, which often leads to tracking failures and causes the gap in performance from other tracking methods. Despite the performance gain achieved by few template update methods with target templates generated by the tracked results, these tracked templates are easy to accumulate errors and cause tracking drift. In this paper, we propose two template update mechanisms to effectively adapt the target template during the tracking process which is dubbed as DTDU (Dynamic Template with Dual Update). Unlike predecessors that directly use the tracked template, we use initial template to perform similar transformation to the tracked template. Then the similar transformed template and the tracked template are combined linearly to capture the variation of target appearance. These updated templates are stored in a memory bank and retrieved to generate the final target template. In order to enhance quick update of memory bank to accommodate the target appearance, we use the retrieved template to further update the templates in memory bank for subsequent tracking. Extensive experiments on OTB-2015, VOT2016, VOT2018 and GOT-10k datasets have proved the effectiveness of these two update mechanisms and the proposed tracker achieves a real-time speed of 44 fps.