Animation basics: The optical illusion of motion - TED-Ed

How do animators make still images come to life? Are the images really moving, or are they merely an optical illusion? TED-Ed takes you behind the scenes to reveal the secret of motion in movies.

Lesson and animation by TED-Ed.

[dianasaurstudio]

I've also heard the persistence of vision called "The phi phenomenon" where the illusion of motion is created amongst like items such as a row of lightbulbs where each instance has a different one lit up

[power-max]

The high the FPS, the smoother the image will look. (30fps looks smoother than 24, 60fps look better than 30, 120 better than 60, you get the idea). However, more frames per second also means more data that must be stored.

[ElNeroDiablo]

Typically, the more frames used per second in a moving image, the smoother the animation appears. And whilst most folks are fine with rates of 25/30 fps (PAL/NTSC TV) or 50/60fps (PAL/NTSC Games, roughly in tune with a 50/60Hz refresh rate), the brain CAN tell a difference in how smooth an animation is when it goes smoothly from 100fps to 300fps, and when there's a sudden drop in the frame rate (say from 300fps to 250fps).

[Tupster]

Images played back at 24fps in a theatre are usually showed twice in order to reduce flicker. Also, they have lots of motion blur. Without the motion blur and showing each image twice photography would not look fluid. This also accounts for much of why video looks so different than film. For a movie you don't really need more than 24fps, but for a video game, which you control, 24fps would give you 40ms of latency, while 60fps is 17ms of latency. Making the game feel more responsive.

[rvd]

A key part that's missing from this video is that the number of frames that exist matter just as much as the rate. A 100 frame animation playing at the same speed as a 20 frame animation will look much different. To answer your question, using the example from the video there were very few frames. So speeding them up to 100 fps would result in a faster animation. At really high fps it will look like all the frames are present at once as transparent layers.

[WiseGuy]

Actually the United States Air Force done an experiment on their pilots. They flashed a picture of an aircraft to them for about 1/220 of a second. The pilots were not only able to see the aircraft, but they were able to identify it too. It's just a matter of time before we will see displays and cameras with even faster refresh rates. Remember that you must think about the number of frames per second "exponentially", ie., the next frame rate with a significant difference versus 120Hz is 240Hz.

[ElNeroDiablo]

Fair point, which is why when film makers are recording at rates like 48-60fps (eg: The Hobbit) they typically have to add-in motion blur during post-production to make it seem more 'natural' to the cinema viewers, but those who enjoy the movies on DVD and Blu-Ray get pissed at the motion blur on an otherwise crisp high-frame rate movie when at home on TV or on the computer.

[philaphobic]

I've heard that when birds look at cartoons they just see the individual pictures. They speed would have to be faster for them to see the movement. But, I'm no expert.

[theanimethief]

the clip that's gonna be played at let's say 48fps will be twice as smooth that's why it's a difference when you play games at 30 fps and 60 fps. The motion and the movements are a a lot smoother. But it also takes a toll on our brain itself. That's why when watching "The Hobbit" at 48fps hurts the brain.

[ElNeroDiablo]

Try playing (say) Team Fortress 2 (1920*1080, everything maxed, fullscreen) for long stretches at 290-300fps, then move into an area with high action that causes the frame rate to drop to 240-250fps. The game play during the rate drop will seem more choppy and laggy (ie: your movements seem to be processed slower than before) than when you were getting the higher frame rate, but is still over 4 times as many frames-per-second drawn than if you locked the frame rate to 60fps (60fps V. 240fps).

[AlexmanGR]

Also if you have an object moving very slowly you wont see any difference from 50 to 300 fps but if it moves very fast you can easily tell the difference from 200 to 300. So the movement of the events in the video are important, you don't need much fps for an romantic show but for a fast video game like cod you need way more fps.

[Felix_yes]

24-30 fps looks like a movie. 40+ fps gives it a more realistic, television-style look. the more frames, the more realistic, up to a certain point, where you don't notice the difference anymore.

[zomicks-bakery-org]

This is beyond cool. Thank you for the enlightenment 

[EASYPEASYDIYFORKIDS]

hey. what software do you use to create your animation? Thanks

[zarkoff]

Also, that frame rate in a camera recording real life movement will produce less motion blur.

[Mad.E]

I'm absolutely no expert, but there are animals that see more or less frames per second than humans do, so for them animation has do be faster or slower (well actually it wouldn't have to be slower but it could be slower and they'd still see motion). But I think if you wanted to answer this question fully, you'd have to take the position of the animal's eyes into the equation too.

[YR]

From 24fps to 60fps it gets smoother and smoother. After 60fps you can't notice the difference, thus 60fps is as good as 100fps.

[gabrcoelho]

When we watch a clip played at a higher number than 24fps, we perceive it as a "weird" image, because the effect we get from videos played in this format is totally different from the real world captured by our eyes, which we can compare to 24fps, so we don't see this type of video smoothly and naturally. Not scientifically, but I hope it cleared something :)

[zobit]

I remember watching QI and they mentioned how a pigeon would be bored at a movie theater because 24fps to it was something like 1-2 fps to us. I'd imagine that based off of that the amount of fps needed for each animal varies.

I'd guess and say it depends on how far the information has to travel from the eye to the visual cortex, with longer distances requiring less fps.

[TheGokki]

Anything below 60 fps i can see the individual frames.
Full illusion of motion only happens above those 60 fps.
It is hard for me to watch movies when i can see every single choppy frame individually and so i use SmoothVideo Project (google it) to make all my video files up to 60 and it is much better and confortable to watch.

24 fps in movies simply comes down to economics - it was, at the time, the cheapest way to get a decent illusion of motion. That's why movies have lots of motion blur.