[NotInControl]

It would be a lot easier, and cheaper to implement a LPS system instead of trying to extrapolate global position via a camera.

The camera would need to be fixed, so mounting it on a quad copter is a no-go if you want accuracy, unless you have some way to track the position of the quadcopter relative to the reference point on the field. A single camera will skew the image so distance will only be if the camera was directly overhead. Plus lighting conditions, and reflective materials unique to each venue will make each site have different behavior.

I do not believe a universal system for all fields, at all events can be accomplished in this manner.

An LPS system is a local positioning system, it works almost as similar to GPS but on a smaller scale. Beacons placed at know locations around a field perimeter each have a unique ID and broadcast the time. A receiver on the robot can calculate distance from it and the beacon by calculating the time of flight between itself and the beacon. (It knows the time the signal was sent because it is in the data, and it knows the current time.) The signal is transmitted via RF, and as such is commonly referred to as WLPS (wireless local positioning system).

Multiple beacons allow for triangulation. If multiple WIFI Access points were added to the field, that would be all that you needed to set this up.

You can do this with many different spectrums with great distance and accuracy. Different systems can be used based on whether you are indoors, or outdoors, and maximum distance. Google's indoor maps uses WIFI signal strength triangulation from known hotspot locations, however for FRC you could do this with beacons using Bluetooth, which would not interfere with the current 802.11 protocol we use for robot control.

Some of the problems with this system would be reducing TTFF. Which is time to first fix, to make it fair, a match couldn't start until each Robot was synced and triangulated.

Just a thought,
Kevin