Triangulation of physical objects

My question is not specifically oF related but if anyone is of the mindset to be able to answer this I figure it’s the oF community.

I’d like to create an installation where several hundred people’s position can be tracked inside a building. I don’t necessarily need to know who they are, but ideally I’d be able to track an individual’s route around a large empty building. It would be great if I could get a ping of a user’s location within a 2 metre accuracy every few seconds.

I’m just starting the process of researching solutions and I’m starting with the following ideas
— triangulation of active RFID with readers scattered throughout the space
— triangulation from multiple local temporary cell towers picking up on user’s phones
— shiny hats that reflect IR bounced from the ceiling (only half kidding about this)

Thanks in advance for your advice.

I’ve done a little but of testing on this in a couple of environments that might be helpful. I would not recommend RFID for large spaces. It works great for small tags in a small distance but you get a LOT of interference as soon as you start to go bigger. Directional RFID readers can work well but can also be quite expensive and hard to rig up in a big space effectively. I made a simple app that uses Trilateration based on the latency between the 3 closest readers and I was able to get a fairly close position coordinates. http://en.wikipedia.org/wiki/Trilateration has some more info.

I was talking it over with some of my friends and one of them recommended using bluetooth or xBee. While it requires a battery it is fairly low power. If you had each participant have say a conference ID badge you could easily put a battery in there and most people would be none the wiser. I haven’t tested this method but it seems like a way to get around the interference.

My purposes was that a client wanted to get a more accurate foot traffic count during a small trade show, where people went, how long they stayed in a booth etc. I never got it fully implemented but it always seemed like a fun idea from an analytics perspective. Hope that helps !

Just thought of this : alternatively if you have a fairly linear experience you could put doorways or checkpoints that users had to walk through. This would allow you to track the time it takes them to move through an experience.