Don't know about these drones specifically, but off the top of my head there are a variety of different navigation systems you could use to supplement GPS for extra precision.

1. Inertial Navigation: basically taking measurements of your speed and direction of travel and using that information to update your position. This is not very accurate, and the longer you go without some other guidance system the less accurate it will get, so I'm not sure how useful it would be here. But it's fairly easy to implement, you just need to give each drone the ability to measure its speed and direction, and you would probably want that to correct for wind anyway.

2. Terrestrial guidance, where you used some fixed landmark or set of landmarks and look at your position relative to it, which can be done with cameras or radar or lidar. Probably too expensive to use radar or lidar, and I'd worry about interference between drones.

3. Command-based guidance. Rather than having each drone try to figure out where it is, you have a separate system on the ground that looks at the drones and tells them where they are. Since you only need one of these command units, it wouldn't be too expensive to use radar or lidar, and no worries about interference.

4. Real-time kinematic GPS: kind of a mix of 3 and 4. You basically have some radio stations broadcasting, and the drones triangulate their position based on that.

Not sure what kind of drones these are, but if they are the Intel Falcon 8+, they have GPS + intertial built in, and they are meant for survey work, so they might have the Real-time kinematic thing also.

Here's an older video about the run-up to Intel's Drone 100 simultaneous attempt. It's the most comprehensive overview of the coordination that I have found. It shows some screenshots of their custom drone control software. In this generation they used 4 pilots for 100 drones; Intel currently holds the world record for simultaneous drones controlled by a single operator at 500 drones, so they have taken a couple steps since this video was made in January 2016.

https://www.youtube.com/watch?v=eZ-js5zn-I0

Edit: found a link for Intel Mission Control. Download it and try it out yourself?

https://downloadcenter.intel.com/download/28715/Intel-Missio...

Edit2: Found a screengrab of the so-called ControlCenter v0.1.6-3-gf79c79. It's pretty hard to read but it's there at 1:06. Also in that same Intel 500 drone video is a screengrab for some software by Ascending Technologies GmbH at 0:40, which Intel bought in 2016. They appear to have created the Falcon 8 drone, which Intel also acquired in the deal.

https://www.youtube.com/watch?v=aOd4-T_p5fA

http://www.asctec.de/en/intel-acquires-ascending-technologie...

This is for sure done programmatically, as you might've guessed. And I'd guess they've built a software that models these animations and treats each drone as a node in a plot and then drones move independent of other drones since their routes are already plotted for them by the software.

So yes engineering wise this is amazing, both software and hardware, but the concept is not that complex.

Think of it as SwarmTouch but without the human "puppeteering" the drones ..

https://www.hackster.io/news/swarmtouch-lets-one-person-cont...