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Tracker variable bounding box size

asked 2017-02-16 04:40:33 -0500

kevin_lomax gravatar image

I'm trying out different trackers implemented in OpenCV 3.2 (e.g. MIL, TLD, KCF) on videos where the size of the tracking object changes in 2D plane due to perspective distortion. More precisely, the tracking object is a vehicle which starts moving very far from the camera, at one end of a road, and approaches to the camera (hence becomes bigger) as the time passes.

However, I realized that except for TLD, all the other trackers keep the size of the bounding box (i.e. ROI) same although the size of the tracked object changes dramatically. Is that the intended behavior of these trackers? Is there a parameter I can change to make the bounding box sizes variable? How is this issue typically resolved in practical tracker implementations? I can imagine this can cause some problems when an object starts approaching (moving away from) the camera and appears bigger (smaller) on the image.


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Hey Steven,

I'm new to OpenCV, could you please explain in more detail what you do to combat this problem? I'm not familiar with local segmentation.

Thanks, Matt

furlongmt gravatar imagefurlongmt ( 2017-09-21 15:11:38 -0500 )edit

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answered 2017-02-16 07:32:24 -0500

Yes that is the intended behaviour, because there is no way of predefining how a window will grow. What I usually do is applying some rough local segmentation and like each 20th frame, I adjust the tracker's region of interest.

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answered 2018-05-28 08:23:35 -0500

Although this is the intended behaviour for most of the trackers, along with the TLD tracker, both the GOTURN and Median Flow tracker adjust the scale of the bounding boxes as they track.

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Asked: 2017-02-16 04:40:33 -0500

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Last updated: Feb 16 '17