How to track arbitration moving objects?
from United States  [214 posts]
9 years

I have been using RoboRealm very successfully to enable my robot to track moving colored objects as viewed through its wireless video camera.  Now I would like to be able to track any kind of moving object, independent of color.

The catch of course is that as soon as the robot moves itself or its camera to track the object, the entire visual field appears to move.  Thus the Movement module can no longer be relied upon to detect the moving object against the global movement of the image.

I suspect that the Visual Anchor module could be used in some way to get around this but my random trials are not getting very far.  Does anyone have a good place to start on this?

from United States  [214 posts] 9 years
That should be "arbitrary moving objects" in the subject!

Anonymous 9 years
See http://www.roborealm.com/forum/index.php?forum_id=1294
from United States  [214 posts] 9 years
Thanks for your reply.  Yes, I already read that thread and in fact, I am already using the Movement module to detect and follow movement.

The problem is following a moving object when the object moves beyond the field of view of the camera.  Imagine a cat walking across the field of view of your robot or surveillance camera.  Using the Movement module, we can follow the moving pixels across the image because the background is not moving.  However, if the cat starts to move beyond the edge of the field of view, we have to pan the camera to keep it in sight.  But as soon as we pan the camera, the entire background appears to move in the opposite direction. Consequently, the Movement module lights up nearly the entire image and the moving cat can no longer be distinguished from all the other pixels.  So during the panning motion, it is very possible we will lose sight of the cat, especially if it is making a lot of turns as it moves.

So the challenge is: how to subtract out all the movement pixels that we know are caused by our own movement?  This is where I thought the Visual Anchor module might help.

The technique I use now is to turn off movement detection while the camera is panning, then turn it on again when it has stopped moving.  But during the time movement detection is off, even a slowly moving object can easily be lost from the field of view.

BTW, when you track specific colors or other easily distinguishable blobs, then you don't have to use the Movement module.  In that case, you can pan your camera almost as fast as the camera's frame rate--e.g. 20-30 times per second.  This results in smooth tracking of the moving object.


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