Ready to get mind bended by these spinning sculptures?
These are 3-D printed sculptures designed to animate when spun under a strobe light. For this video, rather than using a strobe, the camera was set to a very short shutter speed (1/4000 sec) in order to freeze the spinning sculpture.
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4. RetroGrade77 commented 9 years ago
#2 Yes, I think you probably would perceive the effect if you saw the spinning sculpture live. Your question revolves around frame rate. Although the human eye does not have a predetermined frame rate it seems logical that the eye's rhythm or frame rate would work much like stride rate because they are both processed by the same brain. Check out this video.
http://www.snotr.com/video/9540/New_York_Subway_Trolls_Hard
That stair has since been fixed but the reason everybody trips on it is because your brain establishes a rhythm within the first few steps, notes of music, or milliseconds of watching. From that point forward your perception is colored by that rhythm and when a change is introduced to that rhythm the effect can be jarring like with the step or with the sculpture at 0:53 the direction of spin appears to change due to a change in spin speed. So in a sense your eyes/brain does have a frame rate albeit an adjustable one.
http://www.snotr.com/video/9540/New_York_Subway_Trolls_Hard
That stair has since been fixed but the reason everybody trips on it is because your brain establishes a rhythm within the first few steps, notes of music, or milliseconds of watching. From that point forward your perception is colored by that rhythm and when a change is introduced to that rhythm the effect can be jarring like with the step or with the sculpture at 0:53 the direction of spin appears to change due to a change in spin speed. So in a sense your eyes/brain does have a frame rate albeit an adjustable one.
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6. Natan_el_Tigre commented 9 years ago
Faith in chaos restored!
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7. koritheratrat commented 9 years ago
#2 the refresh rate of the human eye is about 24 frames per second (different for every individual but not by much). So if something is spinning at slightly less than 24 turns per second (or a factor of 24, like 48, 72,...) it will seem like it is going backwards. If it spins faster it will look like it is spinning forwards.
If you have the chance, you can make a nice experiment (a Lego set with a few transmission cogs will do the trick, but it should be electronicaly regulated for optimum results) by drawing a black dot on a white wheel and spin it 24 times a second and watch it with your friends. Regulate the spin until the dot is not moving (might be different for every individual), that is the persons refresh rate.
The same effect happens if you watch car rims spinning, one moment they are spinning forwards, the next backwards.
There are a lot of neat effects with digital cameras (rolling shutter effect is one of them).
If you have the chance, you can make a nice experiment (a Lego set with a few transmission cogs will do the trick, but it should be electronicaly regulated for optimum results) by drawing a black dot on a white wheel and spin it 24 times a second and watch it with your friends. Regulate the spin until the dot is not moving (might be different for every individual), that is the persons refresh rate.
The same effect happens if you watch car rims spinning, one moment they are spinning forwards, the next backwards.
There are a lot of neat effects with digital cameras (rolling shutter effect is one of them).
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8. schlafanzyk commented 9 years ago
#2 #4 #5 #7 All of you are wrong even though you get at the right principle.
This doesn't work live without a special setup. Not only is the human eye easily able to differentiate up to some 80-120+ frames per second and then some - I know I am, you just have to know how (24/25 frames is just what we decided to be the minimum and what makes movies look like movies for various technical reasons). But no frequency can ever truly replace constant information like a real life scene provides us with. It's always a percentage, which leads to the creation of this effect in the first place. It's the same with spinning car wheels or the droplets in front of a speaker experiment. It's just a blur in real life unless you introduce artificial AC lighting, a shutter, or something else that can provide a frequency to work with. If you could blink fast and steady enough, that would work as well. Apart from that effect, the human eye and brain work in a more analogue way, processing a constant stream of a changing image (like a DC power supply) not single picture sequences (sort of like AC power out of your wall sockets). Only when moving/blinking your eyes or being in a threatening/stressful situations, you can momentarily notice somewhat of a still image of reality. What we consider smooth motion in film just has to be enough for our brains to accept and interpolate the missing information in between each frame. Our eyes themselves work like a film or sensor that captures whatever information is available over time, continuous or not. If the information is infinitely accurate, there is no room for this effect to show, because the frequency is essentially only limited by the speed of light.
At some point though our brains just cannot process the change in time anymore to recognize it, but that's way past what we consider motion picture. The more aware you are, the higher that threshold where stuttering becomes fluent motion. This however starts out as fluent.
This doesn't work live without a special setup. Not only is the human eye easily able to differentiate up to some 80-120+ frames per second and then some - I know I am, you just have to know how (24/25 frames is just what we decided to be the minimum and what makes movies look like movies for various technical reasons). But no frequency can ever truly replace constant information like a real life scene provides us with. It's always a percentage, which leads to the creation of this effect in the first place. It's the same with spinning car wheels or the droplets in front of a speaker experiment. It's just a blur in real life unless you introduce artificial AC lighting, a shutter, or something else that can provide a frequency to work with. If you could blink fast and steady enough, that would work as well. Apart from that effect, the human eye and brain work in a more analogue way, processing a constant stream of a changing image (like a DC power supply) not single picture sequences (sort of like AC power out of your wall sockets). Only when moving/blinking your eyes or being in a threatening/stressful situations, you can momentarily notice somewhat of a still image of reality. What we consider smooth motion in film just has to be enough for our brains to accept and interpolate the missing information in between each frame. Our eyes themselves work like a film or sensor that captures whatever information is available over time, continuous or not. If the information is infinitely accurate, there is no room for this effect to show, because the frequency is essentially only limited by the speed of light.
At some point though our brains just cannot process the change in time anymore to recognize it, but that's way past what we consider motion picture. The more aware you are, the higher that threshold where stuttering becomes fluent motion. This however starts out as fluent.
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9. celestus87 commented 9 years ago
#8 You are quite wrong as well.
Just because the eye can discern the difference between two specific frame rates, it does not mean that it is actually build for high frame rates.
The human eye does not work alone, it works with a partner called the human brain. And the slower the frame rate of what it perceives, the better since it gives time for its partner to disambiguate the information.
I will not give you a specific number, as there is none. Different people have eyes working best at different frame rates because their visual cortex simply operates differently.
The bottom line is, highest frame rate = most information lost. Sounds counter-intuitive, right?
Just because the eye can discern the difference between two specific frame rates, it does not mean that it is actually build for high frame rates.
The human eye does not work alone, it works with a partner called the human brain. And the slower the frame rate of what it perceives, the better since it gives time for its partner to disambiguate the information.
I will not give you a specific number, as there is none. Different people have eyes working best at different frame rates because their visual cortex simply operates differently.
The bottom line is, highest frame rate = most information lost. Sounds counter-intuitive, right?
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10. YoArgentino commented 9 years ago
You can see it with your bare eyes if it's iluminating with a strobe light.
Eyes doesn't have frame rate, they don't cut live images into frames, they aren't digital nor make samples with a shutter.
Like #5 quote, wheels appear to spin backwards, but only in movies, never in real life with bare eyes.
Eyes doesn't have frame rate, they don't cut live images into frames, they aren't digital nor make samples with a shutter.
Like #5 quote, wheels appear to spin backwards, but only in movies, never in real life with bare eyes.
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11. RetroGrade77 commented 9 years ago
#10 Maybe it's just my eyes that have a frame rate because I have seen car wheels appear to spin backwards when they were going forwards many times. This usually happens when I look at the cars to my side when we are slowing down coming up to a toll booth. It happens with both normal hub caps and spinners.
Or maybe some other factor is in play like a high spot on the disk of a disk brake which causes the wheel to slow down just a tiny bit more during a few degrees of the wheel's spin. With the sculptures maybe it's the shadows that create the strobe effect that effects your perception.
#2 I definitely have seen this effect live. I'm not sure I can pinpoint exactly why it happens but it does happen.
Or maybe some other factor is in play like a high spot on the disk of a disk brake which causes the wheel to slow down just a tiny bit more during a few degrees of the wheel's spin. With the sculptures maybe it's the shadows that create the strobe effect that effects your perception.
#2 I definitely have seen this effect live. I'm not sure I can pinpoint exactly why it happens but it does happen.
+5 1. aaune commented 9 years ago