An 11.3 meter long chamber is set up, filled with normal atmosphere with a relative humidity very close to 100%. A projector is placed a bit past one end of the chamber. This projector must have a very high framerate; the z resolution of the 3D image is the number of frames per second of the projector divided by thirty.

On the same end of the chamber, an extremely powerful bass speaker is set up, playing a tone of precisely 30 hz. At any time, there is exactly one peak in pressure from the speaker in the chamber. At the moment this peak exits the chamber, the speaker produces another one.

The conditions are set up so that water condenses from the atmosphere briefly as every peak passes. This creates a 340 m/s diffusing screen that sweeps the chamber 30 times per second, on to which the projector throws an image. The illusion of a 3-d image is produced.

Note: This projector is likely to be somewhat loud*. It might be better used for hard core metal concerts in the middle of the desert than inner city movie theaters.

*absolutely ridiculously loud: Although I have not done precise calculations, it is plausible that the 'speaker' would be better described as a 30 Hz Bomb, as actual shockwaves are the only type of sound I know for a fact can cause instant condensation. Constructing the speaker is it's own engineering problem. I suggest something involving an explosively detonating gasoline vapor mixture. However, this aspect is up to individual site managers.
-- quadmaster, Nov 01 2011

Prandtl–Glauert_singularity http://en.wikipedia...Glauert_singularity
The effect that creates the screen [quadmaster, Nov 01 2011]

'Voxel' principle this is based on http://www.cs.man.a...writing/PCW/vol.htm
[quadmaster, Nov 01 2011]

Come on, you don't need to use an explosive device in your speaker. You just need to have a number of fighter jets flying past in close formation such that you get 30 of them fly past every second.
-- scad mientist, Nov 01 2011


Retiring to write Music Of The Spheres, based on the sounds generated by colliding stellar bodies.
-- theircompetitor, Nov 01 2011


[+] beautiful.

At the risk of suggesting an implementable alternative, how about a using a wind tunnel with multiple pulsed bubble generators? A wall of bubbles would then whoosh down the tunnel, performing the same function as your wall of condensate, but less noisily.
-- MaxwellBuchanan, Nov 01 2011


The '30 Hz Bomb' speaker could probably be accomplished with a repetetive high-amperage electric arc of enourmous diameter (I'm thinking along the lines of three or four feet) and some artfully arranged baffles to enhance the resultant stacatto of thunderclaps. A bare arc would mesh nicely with the gasoline vapor feature, as well.
-- Alterother, Nov 02 2011



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