how to initialize the Tracker several times using opencv_contrib?

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I am using opencv_contrib for TLD tracking. Firstly, I use one algorithm to detect moving objects with moving camera. Then I want to track the detected objects. Sometimes the objects may be out of sight. So I decide to initialize the TLD tracker again. However, when I tried to use the Tracker->init() for second initialization, it always failed.

Also, I have read part of the source code about the tracker. There are two reasons that can lead to the failure. But I still do not know how to solve it except modifying the source code.

Can anyone help me? Looking forward to your advice!