New exercise added 5-2-2016: Overlap/waving motion
New exercise TBA
Heya everyone, Unbounded here. Since I figured this spot was lacking some activity, and because I find things way more fun when other people are joining as well, I decided to make a fun ol’ thread where we can really just take a step back, and focus on learning the basic animation stuff, the fundamentals, really well. Like, really really well. You know, stuff like the bouncy ball, walk/run cycles, etc etc etc.
Oh, and I’m going to be tackling them in order. From the very bottom, (ball bouncing, no decay), so regardless of animation ability you should be able to jump in and participate. Heck, pretty much everyone should be able to benefit from this thread anyway.
“But Unbounded!” You might say, “I’ve already been animating for X amount of years! I’m already above this!”
Well, sure, I thought that myself. I’ve been playing with animation for roughly a year myself, but when I do a bouncy ball exercise I still get some weird results like
this. Until you try it you can’t figure out if you have mistakes in the first place!
But for a better answer, no, no you aren’t above the basics. Industry professionals aren’t above the basics.
https://www.youtube.com/watch/?v=l_q6eyswBD4
Here’s an example of a pencil test from Milt Kahl for Bambi. Freakin’ Bambi. It’s basically modeled as a bunch of bouncing balls. It’s important. Trust me. Learning and practicing this stuff will improve every animation you work on from here on in.
Convinced yet? Good! Let’s get started then. The first few exercises will be listed below:
Absolute Beginner animation exercises (Taken from 11secondclub forums):
1: Bouncing ball, no decay. (Loop)
For this exercise we’re just going to be taking a single bouncing ball. It starts at the top, falls vertically, and is nondecaying. This means that there is no energy lost due to air friction, and there is no energy lost in the ground, and as a result the bouncing ball always ends at the same height that it started. It’s the perfect, ideal universe.
There’s no horizontal motion yet. That comes later!
I'll be posting tips for each of the exercises as I find them. I know I'm looking up ways to improve on this stuff myself. I see no reason why I shouldn't share this.
First things first, you start off with a bouncing ball, the bounce is starting at the top, is looping and non-decaying.
There are several tutorial on bouncing balls on the internet, so I'll just keep to the basics, for further infos, Steve compiled quite a lot of really good tutorials on the 11secondclub blog site and I very much suggest you regard some (or all) of them before starting this exercise.
As a ball rig, you can use whatever sphere you like, there are tons of rigs out there, too, and I made one as well (for Maya only), which is freely downloadable, together with an obstacle course (you might need that later on) here.
So, looking at it physically, when a ball is bouncing, gravity is pulling it down until it hits an obstacle (the ground), the energy it gathered while falling is converted to elastic energy (the squash) and directly converted back to kinetic energy the other way, driving it back up until this energy is less than the gravitational pull that makes it come down again eventually. There is also a fundamental law of physics that no energy is ever lost.
So, in an ideal universe (not the one we live in) this could happen, without any further interference, indefinitely, which is what we assume in this first 'lesson'.
At this point, we halt the physics lesson until the next step, and look at it from the more artistic side:
While animation can break the laws of physics in every way the animator wishes, good animation still adheres these laws, while merely bending them. Joyce wrote some more about this in her brilliant article on consistency.
When a ball is falling in real life, it actually stays near to round all the way (if you don't believe me, look at a falling drop of water), but in animation, historically mostly in order to compensate for the missing motion blur, objects have been made to stretch more the faster they get. This is physically not wrong, its just very exaggerated, and with us being accustomed to this behavior by looking at cartoons for the last century or so, stretching has even been made a synonym for movement. (When you're at the point of animating characters, you will come back to this principle and see the whole business in a whole different light)
So, in order to do this right, here are the main pointers:
-On its Zenith, the ball is not moving at all.
This fundamental knowledge (I am not kidding you) means that at this point only, the ball is nether stretched nor squashed.
-On its way down, the ball gathers speed exponentally
This of course means the decline of speed on the way up is happening in the same way. It also means that the stretch of the ball should not be much visible as long as the ball is not moving much, otherwise you'll have something that rather looks like a wobbly soap bubble.
-Immediately before and after the contact, the ball has its highest velocity.
This knowledge is fundamental, too, and means that, while the ground is changing the balls direction, it does not slow the ball down. (remember we are still in this ideal universe) In order to animate this correctly, you have to break the tangents of the upward movement's curve on this frame.
It also means that in the frame before and after the contact, the ball is stretched out the most.
-The ground contact is very short
meaning it usually only takes about one frame, seldom two. If you take longer, the ball suddenly has a will of its own, and we have a jumping ball, not a bouncing one. It's nice if you can do that, but let’s keep the ball inanimate for the moment.
This also leads to a very big shape change in a very small amount of time, in order to not have this look strobing or have the onlooker loose the ball, we usually have the stretched ball touch the ground very slightly on the frame before and leave the ground by just a fairly small bit on its way up.
Repeat this exercise until you really nail it, and then probably repeat it some more. This is the fundamental on which everything else will be built on, even highly complex stuff like facial animation.
Unbounded
First attempt
Critiques:
Second attempt
Critiques:
Third attempt
Critiques:
-I may have screwed up the Apex of the bounce a bit. It's falling a tad too soon.
Tun3
First attempt
Critiques:
-Too linear. Focus on the spacing.
-Needs some squash and stretch.
chantful
First attempt
Critiques:
-Good bit of easing into the motion.
-Spacing too constant towards end of animation. Keep increasing the spacing until the contact.
-Stretched too much right before the contact position.
hamnet
First attempt
Critiques:
-Very consistent volume
-Solid spacing
-Overdone squash upon contact
This is similar to the first one in that we’re working with a bouncy ball, but the big thing here is that it’s actually decaying, meaning that it is losing energy. The heights of the bounces will gradually decrease until it settles at the bottom. This one is actually pretty powerful, and by simply changing the timing of the bounces and the heights of the ball you can easily convey what type of ball it is. (We’ll get on this a bit more later.)
Next step will be, after we nailed this, to take this ball out of its ideal universe in our own.
Thus follows another lesson in physics. (sorry )
As the ball loses its kinetic energy with every time it bounces, mostly due to heat and friction, but the gravity and the elasticity stay constant, the amount of height declines with every bounce. Like with most things in nature this decay is also exponental, and affects the frequency of the bounces accordingly.
Meaning: The bounce of the ball will decrease by a constant amount every time it bounces, and the lower the bounce, the shorter the time it stays in the air.
Without further ado, now follows the lesson with the ball bouncing in place with a settle to a stop.
Here are some more pointers:
-The ball should stay consistent in all its attributes
meaning, that even if the ball is squashing like a pancake, it has to stay that way and, even though the amount of squash reduces with every bounce, it should reduce according to the decline of the bounce height. Same goes with the stretch, of course.
Repeat this exercise until you really nail it, and then probably repeat it some more. This is the fundamental on which everything else will be built on, even highly complex stuff like facial animation.
Unbounded
First attempt
Critiques:
-Overused squash and stretch.
-Ball is on the ground for way too few frames.
-Ball squash on contact barely changes.
Second attempt
Critiques:
Third attempt
Critiques:
-May have added too many frames on third bounce.
-still seems to become too rigid towards the end of the animation.
-heights/bounces seem a little off.
-The transition to the stretched positions could follow the motion more closely.
Fourth attempt
Critiques:
hamnet:
First attempt
Critiques:
-Great volume consistency
-Overdone squash
-Lost a bit too much height on second bounce
So this is pretty interesting. With the previous two exercises we were getting a hang of both timing and spacing. We tried to make some random circular object convey the idea that it was a ball.
It turns out though, that by varying the timing and spacing of the bouncy ball animation, we can make it seem like a completely different type of ball! That's exactly what we're going to be doing for this exercise. Tweak the timing and spacing to make a few different kinds of balls. Because I want to keep a bit of focus, I'll recommend a few types of balls to focus on:
A bowling ball
A golf ball
A water balloon
A regular inflated balloon
A lump of clay
Really, there's any number of objects you can try out, I just think those are some good ones to play with. Good luck!
So the two big things you want to keep in mind are A: How hard is my object and B: How much energy does it retain on impact.
An object like a golf ball is hard, so it won't have very much squash and stretch, but golf balls are pretty elastic and maintain a good chunk of their bounce height.
A clay ball, on the other hand? Not quite as hard, but it's pretty inelastic. It loses pretty much all of its energy upon impact, but it's able to deform a decent bit.
Here is a good video on the subject
As long as you ask yourself "how hard is this object" and "how high would it bounce?" You'll be well on your way with this exercise.
And since it'd honestly be pretty difficult otherwise, here's a little bit of reference:
Sports Balls Bouncing
Bowling Ball Bouncing
Now I'm gonna swerve from Stefans original list as I am going to add another bouncing ball exercise before moving the ball forward.
In this exercise you'll repeat the bouncing ball exercise, but by varying the timing and spacing of the ball, as well as its size, bounce height and amount of squash/stretch, you generate the impression of different ball types, for example:
A bowling ball
A ping pong ball
A rubber ball
A balloon
A soap bubble
A lump of clay
...
Again some physics, as the weight of the object gets canceled from the equation, all objects fall with the same speed. The only way an object can fall faster than another is if you either give the object some sort of propulsion and speed it up or apply the air resistance and slow it down.
Meaning, the faster an object falls, the greater the air resistance, until at one point it cancels the force pulling the object down (the objects mass). The bigger the objects mass opposed to its aerodynamics, the faster it can fall. One example are parachuters: If the person falls down head first (reduces the air resistance to a minimum), he can get to a speed of roughly 300 km/h, if the same person spreads out his limbs and falls like this, his speed is reduced to (I think) roughly 120 km/h. A falling beetle would probably never travel faster than 30 km/h. (just to add a few numbers, Joseph Kittinger jumped from an altitude of 31,333 meters, and due to the lack of air resistance at this altitude reached a top speed of 988 km/h)
Though most of my guesses at these speeds are wildly inaccurate, I believe you get the idea smile
So, as the balloon and the bowling ball have roughly the same aerodynamics, but the bowling ball has a much greater mass, it will fall down much faster than the balloon, but(!) the acceleration until (in this case) the balloons maximum speed is identical!
A few pointers to that as well:
-If an object is non-elastic, it will not rebound
meaning, if a bowling ball is hitting the ground, it usually is the ground's elasticity that makes it jump up again, and not the balls.
This also means that if the ball (or the ground) is deformed above its elastic limit, there will be no rebound either or it will be greatly reduced. As an example, take a ball and throw it into the sand, or take a slap of clay and throw it on your kitchen floor.
-If a ball is extremely light, it travels downwards more or less linearly
meaning that if, say, a balloon is falling at 30cm/second, it reaches this speed very fast and then stays at this speed, until it hit the ground, from then on it decelerates, naturally smile
Having no big mass and speed, the Balloon will not deform much when hitting the ground.
-From a normal size/mass ration upward, the difference in speed due to air resistance can probably be ignored
from 1 Meter, a soccer ball falls pretty much as fast as a bowling ball.
Repeat this exercise until you really nail it, and then probably repeat it some more.
Unbounded:
Attempt 1: (In order: bouncy ball, bowling ball, golf ball, water balloon, lump of clay, air balloon)
Critiques:
Second attempt
Critiques:
This one is pretty similar to the first exercise, except now we acknowledge the existence of a second spacial dimension!
It's going to be a ball that is bouncing horizontally across the screen. There is no decay in height. To make it a little bit more interesting though, let's also put a bit of spin in there. Simple enough, right? It should be a bit of a break after that last exercise!
Some things to keep in mind:
-Arcs! Remember that most natural motion moves in arcs. This case is no di
