[Sohcahtoa82]

> The Vive/Index uses its camera to detect the motion of fixed markers (the lighthouses)

This is inaccurate.

The lighthouses scan the room with lasers. The dimples on the Vive and its controllers detect the very precise timings of getting hit by the lasers from the lighthouses and derive their location and orientation relative to the lighthouses.

This is how the Vive supports easily adding Vive tracker pucks to the room to add body tracking to games like VRChat. The lighthouses are passive and don't care that there are more devices to track, as each device tracks itself.

There's a good video explaining it at https://youtu.be/J54dotTt7k0