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Comment by brittohalloran | Hacker News Reader

They need to incorporate location of the wristband with some sort of triangulation between transmitters. Then they can make it an actual display. I'm sure this will happen in the not too distant future and I'm excited to see it.

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Another interesting option would be to have the wristbands communicate by radio with nearby wristbands. Probably not useful to draw precise stuff, but could be fun to have possibly beautiful abstract patterns like cellular automata.

Using highly directional antennas on the transmitter should be able to accomplish similar results without increasing the cost of the wristbands.

What if these bands are paired to phone via bluetooth so that the base station can send commands to the phone (through the mobile network) which in turn relays it to the band - would it allow a more fine grained control with acceptable latency?

Latency would be huge with that setup. 900mhz radio has more than enough range and bandwidth to handle 50,000 - 60,000 devices updating several times a second. I've used LSR [0] modules in the past for prototyping and they have a gateway that would allow you to control the entire thing through ethernet so any computer could run the program and just spit out ethernet packets to send control information.

[0] http://www.lsr.com/

Modulating the antenna's attenuation would add depth-control, which may also be interesting.

You wouldn't even need direction antennas to do this, just some number of reasonably spaced omni's that could feed signal strength information. The problem with this approach is that the wrist band needs to transmit to make this at all useful which adds cost to its design vs being a simple receiver only.

I mentioned this in another comment but it should be easy to correlate a seating assignment to a wrist band MAC giving you reasonably good location information. It wouldn't work "in the pit" obviously but you would be very hard pressed to get any accurate enough location data in an area like that.

As ZTO and bluesnowmonkey pointed out, if the wristbands became individually addressable, you could determine their locations in the crowd using an overhead camera and a quick calibration routine (which the audience would just think was part of the intended effect; It would just look like more random flashing).

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