OpenCV tracking people from overhead view

I have a broad but interesting OpenCV question and I'm wondering where to start. I am looking for any strategies or white papers that might help.

I need to get the position of people sitting at a conference table from a fixed overhead view. Ideally, I will assign a persistent ID to each person, and maintain a list of people with ID an开发者_Go百科d coordinates. This problem could be easy in a specific case - for example, if designed for a single conference room table - but it gets harder in the general case, especially with people entering and leaving the scene.

My first question: is it a detection or a motion tracking problem? Or some combination of the two?

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Well it seems like both to me. I would think you would need to take a long average of the visible area which becomes the background. Then based on your background information you can track movement of other objects.

Assigning an ID may become difficult if objects merge together (at least as far as the camera is concerned) and then separate again, say someone removing a hat placing it down and placing it back on.

But all that in mind it is possible even if it presents a challenge. I once saw a similar project tracking people in a train station using a similar approach (it was in a lecture so I can't provide a link sorry)