In recent years there seems to be a wave of Audience Interaction (participation?) technologies. Here I just list a few that I am aware of, if you know others, let me know!
One of the earliest systems I know of is an experiment by Loren Carpenter presented at the Siggraph conference in 1991, (historic video here). He provided an audience with small paddles, reflective green one side and reflective red on the other. Using cameras and some algorithms he projected just these paddles on a screen. Then he went through a series of applications for these image processing algorithms. Ranging from simply showing the paddles as pixels to having (parts of) the audience control the movements of game-elements depending on the red/green ratio. For example the paddles of a game of Pong.
This technology was patented and further exploited in a company called Cinematrix.
At ICMI2002 , Dan Aminzade, Randy Pausch and Steve Seitz presented work on Interactive Audience Participation. On his (old) work pages, Aminzade presents some of the ways the techniques presented were implemented. Watch him talk about it:
Less interactive, but still causing awesome effects are systems that more or less turn audience members into pixels.
in 2012 FanFlash saw its premiere on German TV:
Recently you may have seen the halftime show of the 2014 Superbowl. It’s the clever guys at PixMob that were responsible for the light effects there.
They have done and are still doing various versions of their technology for turning the audience into pixels that are part of the light show. My personal favourite is the beachballs at Coachella in 2011.
Someone who has always been very effective at engaging audiences is DJ Tiësto. He uses PixMob’s audience-as-pixels technologies well in his sets.
Another company, Embraceled, has a similar system that was used at at a party called Sensation.
They also promote another application for business events, that bridges online and offline social networking. (Warning: corporate company presentation video with cheesy background music, in dutch)
People as pixels centrally controlled, reminds me of something:
I am still musing on what axis or in what space these different projects may be placed.