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How do you think this awesome light installation achieved this effect? Answered

So I'm recounting this from memory. I was in Argentina several years ago in a nightclub and there were these bars of light on the wall. I can't remember exactly what they looked like but it was a vertical bar of light, maybe 3 feet tall, very thin. When one whipped their head back and forth while dancing, a full size image outline (appearing 4 feet wide) of in this case the Camel cigarette logo would whip out in the direction of your rotation. So basically this full width image was stored in a tiny space, and when you rapidly rotated your head, the full image would emerge in the direction of your rotation. You went left, the camel would emerge following the bar (on the right) and it would face the left, whereas if you went right, the camel of course emerges following the bar on the left and it would face right.
Woa!
Any ideas?

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The Skinnerz
The Skinnerz

8 years ago

The bar is actually scanning across the image, so while the lights appear to be on constantly, they are actually flashing too fast to see. As your perspective (or the light bar) moves, each pattern of lights appears at a slightly different position in your field of vision, building up a picture line by line. It works by persistence of vision whereby the image of the lights remains in your eyes for a short period after they move, allowing an image to be built up.

There are a number of similar POV projects on this site that may help explain.

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prismspecs
prismspecs

Answer 8 years ago

I figured this was the case, but how does it always end up in the right order?

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iceng
iceng

Answer 8 years ago

Same way an old TV screen raster scan works.

There is a longer dead No light moment and your brain working in
concert with your eyes POV is able to stabilize what you perceive..

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prismspecs
prismspecs

Answer 8 years ago

So it scans through the columns, let's say 1ms each, then pauses for 10ms or so, then repeats?

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iceng
iceng

Answer 8 years ago

Very correct !
It may be slower about half as long as it as it takes to rotate your
head 90° in a disco dancing environment for a full cycle including
the dead time.

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kelseymh
kelseymh

Answer 8 years ago

Because the sequence of patterns is generated in the right order on the light bar. It's your brain (visual cortex) which puts them together to appear to be an image.

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mpilchfamily
mpilchfamily

Answer 8 years ago

+1 Look up Persistence Of Vision (POV).