/diy/ - Do It Yourself

>>883458
I would get a microcontroller with multiple photodiodes, one diode for every position.
For every photodiode there is a corresponding led which lights up in proportion to the amount of IR light the photodiode picks up.
I know for sure this method works very good for short distances, but I'm not sure about 1m+, you might need to put a lot of IR leds all over the place (on the ceiling).
You also might have to make some kind of funnel for the photodiodes, or it might also pick up reflection that's not immediately under the diode.

This is only a matter of aesthetics, but I would also recommend letting the LED's fading in and out for a smoother transition, when someone moves around under the photodiodes.