Page 1 of 1

Optical illusions

Posted: Thu Jul 19, 2007 6:33 pm
by alex.barylski
In Googling for an explanation as to why high speed fan blades appear to occasionally spin in the reverse direction, I managed to find these. Trippy. I've always been amazed by artists. I especially like the sidewalk 3D stuff. I seen that here once and WHOA...felt like I was falling in the sewers it was awesome!!!

http://www.feedshow.com/show_items-feed ... 217ddb493b

p.s-As for my own search I assume it's because the tip of the prop is moving faster than the center? Anyone know of reference which explains this phenomena?

Posted: Thu Jul 19, 2007 7:20 pm
by Benjamin
LMAO @ http://bp1.blogger.com/_cxmptAPYR-s/RpE ... 74c7_o.jpg

Smoking a cigarette, pumping gas.. I love it.

Posted: Thu Jul 19, 2007 8:20 pm
by alex.barylski
Those were funny. The woman in the ashing machine was good too.

Re: Optical illusions

Posted: Fri Jul 20, 2007 5:23 am
by Chris Corbyn
Hockey wrote:As for my own search I assume it's because the tip of the prop is moving faster than the center? Anyone know of reference which explains this phenomena?
It's to do with the rate at which your eyes refresh what you see (read, the rate at which your brain interprets the image). The fan spins, and as it does so each fan blade moves. If your eyes next see the image in X milliseconds, the blades may be slightly offset which makes them appear to have moved backwards.

Posted: Fri Jul 20, 2007 10:34 am
by ReverendDexter
It works with wheels on cars/bikes, too. You can see it easier on tv, as the frame rate is slowed down (I believe normal tv is still only about 30 fps).