[quickthrower2]

Tennis courts in my area need to be booked, so it is pretty simple: have you booked? I am guessing this is for tennis courts that are not booked but you just rock up. The only way I can think is computer vision and surveillance of the courts. But it could be lowish resolution. A single well positioned ring cam could probably cover multiple courts for "is someone playing" detection.

[zerojames]

A colleague worked on a similar project, but for detecting if there was a free court outside his house where he could play: https://blog.roboflow.com/computer-vision-twilio-notificatio...