Is there a way to count how many tagged objects there are in a set area?

I think there are several solution to this:

• Use a big bounding box that cover the entire area and get all the tagged object inside.

• Get set area center point then calculate the distance between that center point and all tagged objects in scene, return the ones that close enough

• Put bounding box in all the exit and entry to that area so you know which object go in and which object go out. Each area will have list of object that are inside that area, etc etc...

Just think all of those off my head, so sorry for no sample code mate.