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I have been looking into object detection and tracking for a project that I am working on but I can't yet seem to find any techniques that I can make use of to utilise the information from object tracking to determine the direction of travel.

Ideally I'd want to find out whether the object is moving towards or away from a camera.

I could not find what methods exist out there or perhaps where and how to search for them, I am looking through OpenCV for any possible methods it offers.

Currently I could only think of two methods:

  1. Object size based, if the object gets smaller or bigger then it is either moving away or towards the object but this is very dependant on the cameras position.
  2. Object coordinates based, sounds a bit too simple to be true but can't think of why it won't work or what disadvantages it has.
Abs
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    You'd need to not only project a 2d curvature of the projected path, but a 3d curvature (with the 3rd dimension being time). Only an accurate prediction of this 3d curvature will let you make reasonable guesses on depth based on its current size. – Neil Sep 11 '18 at 13:50
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    Probably worthless in your specific case: astronoms use Doppler effect to track celestial object direction of travel and speed. – mouviciel Sep 11 '18 at 18:36
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    You might look into [optical flow](https://en.wikipedia.org/wiki/Optical_flow) for calculating the direction and magnitude of motion. – user1118321 Sep 12 '18 at 04:30

1 Answers1

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  1. is possible - but not very accurate - and also needs to know the actual size of the object being tracked (assuming only AE track) for distance estimation. This might be acceptable if all you want is its getting nearer/or getting farther away and you know the object cannot change size

  2. is of course possible if you already have 3d coordinated, the complication being that with just a camera you will normally only have 2d (e.g. Azimuth Elevation)

ultimatley you may need another sensor e.g. a laser range finder or self reported position from the object iteself to fill in the missing information as camera will only naturally give you a AE track

jk.
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