Would help to know which drones and/or the software/OS controlling them. Many drones already have APIs that can give you X/Y/Z positioning data. If this is in

Would help to know which drones and/or the software/OS controlling them. Many drones already have APIs that can give you X/Y/Z positioning data. If this is indoors you may not be able to rely on GPS data, but you may have options for other coordinates based on triangulating wifi control signals. Doing it with machine vision would likely be challenging (and I say this having a fair bit of experience with AI/MV systems). The area you are covering a very large field of view, and drones are generally very small relatively speaking. If you can't do it with native APIs, I would probably look into an RF style system with a small transmitter on each drone and then antennas places around the stadium to detect and triangulate the signals into 3D space.