Tom's Journey Into Animation Part 1 - The Bouncing Ball
Hey guys.
Well.. it begins.
Quick backstory - Few months ago, decided to enrol on Animation Mentor, got enrolled, excited to start.. decided £12k would be better spent on a house - decided to attend Polycount/11SecClub/CGS Mentor instead.
So here's the obligatory bouncing ball. The idea is to get each stage looking good before I progress. Once you guys in the know give it the all clear, then I move on.
I know to most of you this is gonna be like 'so, yeah, it's a bouncing ball'... but it's important I get this.
Go!
http://vimeo.com/24262196
EDIT: Why why why do videos I link never embed?!
Well.. it begins.
Quick backstory - Few months ago, decided to enrol on Animation Mentor, got enrolled, excited to start.. decided £12k would be better spent on a house - decided to attend Polycount/11SecClub/CGS Mentor instead.
So here's the obligatory bouncing ball. The idea is to get each stage looking good before I progress. Once you guys in the know give it the all clear, then I move on.
I know to most of you this is gonna be like 'so, yeah, it's a bouncing ball'... but it's important I get this.
Go!
http://vimeo.com/24262196
EDIT: Why why why do videos I link never embed?!
Replies
I suggest uploading a .mov or .mpg into a "dropbox" account, in the public folder, then right click the file and copy the public link, then post it here. that way we can scroll through your stuff frame by frame.
www.11secondclub.com is a great place for animation crits as well. You should check it out.
I have done that and I know how hard it could be to get it right from the beginning. In the school I was going in the teacher gave us all balls and we went outside and started experimenting, made a video and went back and started studding it frame by frame
It looks fine so far, perhaps you could polish it up some more. Give it some life.
Perhaps try making it bounce up a bit slower than going down, and work on how high is the ball going after every bounce - should be decreeing if it is not one of those crazy silicone balls.
So you gave up on Animation Mentor ? I was so exited for you . Lets hope this is going to be as good and let us know how you feel there
When you say mid bounce Slipsius do you mean in every bounce? There's a weird bit about 7 secs in but I'm not sure what happened since I just cycled 20 or so frames for 10 secs in Maya, so technically it should all be identical.
Thanks for the tip on Dropbox too, I'll get it hooked up.
Stinger: Yep, that's next!
Disanski: Thanks man. Yeah I love animating, I've really taken to enjoying it.
Yeah I pulled my enrolment from AM. I wish I coulda done it but it just came down to money. I'm currently house hunting with my fianc
It obviously missed squash and stretch, but the timing seems to be working.
Nice presentation too btw, makes stuff more fun to look at than just viewport shots.
edit:
I just noticed that the falling down part makes it seem like it's getting bounced rather than it's just bouncing by itself. If that makes any sense?
As if it's getting help to speed up the falling down process and not just gravity doing it's thing.
The timing is a bit off, its very linear. It moves at the same speed at the top of the arch that it does after impact and recoil. Typically you want to stretch out the keys near the top of the arch so you get it to slow down and almost hang at in the top most position. This helps you to show the transition in kinetic energy as gravity starts to overcome the balls own energy. It takes gravity a little bit to exert its full force and drive the ball back down which is why it picks up speed as it nears the ground. You can do this by adjusting the curves, or by adding more keys, it's up to the animator and both are just as valid as the other, sometimes for certain situations you will want to use one over the other but be careful of people who always preach one or the other...
One of the great things about the bouncing ball is mastering how it slows down and settles in. Typically on each bounce the ball will bounce half the height of the previous bounce. This is where the curve editor comes in handy your Y position curve will look like a ball bouncing from left to right, it will also help you catch mistakes like the one down key that stops about half way, heh.
One of the other good things, is that you should learn to animate it bouncing from left to right or right to left, hitting a wall reacting and coming to a stop. Anyone who thinks its easy needs to give it a try.
The rotation can be maddening so at first you shouldn't worry about it but at some point it might help to apply a large checker pattern to the ball to help you watch how it rolls.
One thing that can help, if you know how to run simulations is to bounce a ball around a scene watch how it reacts. This is infinetly more helpful than just watching a ball or even shooting video of a ball. 1) you probably don't have a high speed camera capable of shootin at 24-30 frames per second, 2) you can bake it down and look at it curves and really dig into the animation, you can also tweak the sim and see how it reacts.
Now for anyone who thinks oh ok just sim a ball and you're done, you miss the point... its an aid you're learning some very fundamental things that transfer to a lot of other stuff relaying on sims and a lot of technical rigging will only slow down your learning, so use them wisely and as ways to learn not as a crutch.
Ok I've tweaked the timing a little. I'm still not sure if there's enough hang time, maybe a touch more?
I added squash/stretch too. Looking at it now, I'm thinking there's a little too much squash on the contact?
Also, having a weird issue with the output somewhere between Maya's TIFF output, and AE's MOV. In Maya, it's just a single bounce, 24 frames long which is cycled over 300 frames. So every bounce should be identical, but it's clearly not. There's one or two odd bounces where the ball doesn't hit the floor?!
Anyway, not really relevant I suppose but annoying nonetheless.
http://vimeo.com/24271604
Dropbox: http://dl.dropbox.com/u/4627207/Animation/Ball%20Bounce%202.mov
It needs to fall, hit and stay on the ground while it compresses/uncompressed then as it's scale/shape starts to recover it can start to move up again. If you look at frame 11 it should be on the ground while its compressed.
As for the weird ball bounces, it might be AE not interpreting the footage correctly? Maya set to 30fps and AE interpreting it at 24fps? I always have a problem with AE not interpreting the footage correctly and have to reinterpret the footage after its imported. I think Maya comes with "Composite" which might be a better option for you than AE.
Ok following your comments, I've extended the contact pose a touch, and smoothed out the squash/stretch at that point. I also added a tiny bit more hangtime at the top of the bounce.
Any further crits?
http://vimeo.com/24284720
EDIT: Also, you should be able to download the clip straight from Vimeo, let me know if you can't and I'll DropBox it.
Oh yea I forgot Vimeo lets you download videos if you log in, I'll have to keep that in mind.
next exercise I suggest the same scene, but treat the edges of the screen as a box and the ball is bouncing inside the box until it eventually stops.
After that you can try doing the same for balls with different mass and hardness.
Ok, following a couple of crits on 11SC I've adjusted the timing slightly, made the up-bounce a little quicker.
Onto the next!
http://vimeo.com/24287663
It's embarrassing that I spent most of my time on the graph editor and I'm fully aware of how tangents work, yet I managed to make the up curve look very linear.
Thanks for pointing it out, I'll fix it when I'm back on it tomorrow!
http://vimeo.com/24307217
Here's the Y Curve, if it helps crit.
The down side is you can easily fall into the trap of working on the same thing over and over again and not branch out as fast as you might while in school.
Yeah I see what you're saying. That's one of the reasons I'm so pleased I got so much feedback, and so quick too, it meant I could refine it and make amendments and get it done in a short time without hanging around on the same project for too long.
Next up I'll let it bounce to settling, probably just vertically first. I just want to nail the physics in one direction first then I'll add in horizontal motion. I'm guessing once the Y is sorted, I can add the X in and keep the vertical motion as it is.
The tail/obstacle course are great ideas too, excited to get onto those!
Crits please!
Also, is it normal to need to edit the tangent weights? It's not something I've done very much but with this exercise I found I needed to do it on almost all of the keys? I'll upload the .mb so you can check it out if you like (Maya 2012)
DropBox
Maya Scene
http://vimeo.com/24329867
Here is a good tutorial; http://www.idleworm.com/how/anm/01b/bball.shtml
Ok I'll change it up, you're right, my curves are not equal at all, and I did that deliberately so I was wrong in doing that. Currently the curves are much steeper on the up than the down. For some reason I was thinking the ball should bounce up faster than it falls, but it seems making it more even looks better.
Also, that'll explain why I had to mess with tangent weights more than I felt I should've been.
Awesome, can't wait to get back on it now, but sleep beckons!
DropBox
http://vimeo.com/24380361
53-54 has some spacing issues, smooth that out a little. And because the ball is always deforming in the beginning it gets a certain character. Though in the end the ball is rigid as ball made of metal. Either tone down the squash in the end or crank up the squash towards the end.
I've gone back a step following some comments on 11SC. I've implemented a basketball now so it's clear what type of ball weight I'm aiming for.
I've also taken out S and S for now while I a) I figure out how to add it to my own geometry (was using a rig before) and b) get this looking good without it. Also, I'm not sure a basketball should have any deformation really, unless I'm going for a stylised look.
http://dl.dropbox.com/u/4627207/Animation/Basketball%20Bounce.mov
Anyway, I think you should think of exaggeration when you think of the squash and stretch. You might want to tone it down but not remove it if you want a, possibly, more interesting ball bounce. The problem before has been that you've been relying on interpolation on the squash and stretch when it should be used as comic contours, in the end for that extra flare.
Here I have my own little contraption I made a couple of days ago while procrastinating. There's a toony feel to it and there is motion blur but you should get the jist of it. http://dl.dropbox.com/u/8701158/CexarBallBounce04.mov
Don't. Your animation alone should be able to convey that.
Again, don't. Squash and stretch is an intergral part of this exercise. It will affect the timing and placement of your keyframes. Everything follows the principle of squash and stretch, even if it doesn't deform...which a basketball most certainly does.
Some study questions for you:
What principles of animation are you working with in this exercise?
What laws of physics are you dealing with and how do these apply to the principles of animation you're dealing with in this exercise?
How would this animation be different for a small rubber ball, a baseball, bowling ball, or a balloon? Why?
It's interesting you made these points because it highlights something that's been on my mind. One thing I'm aware of with animation is that a hugely important factor in any animation is appeal. While doing these ball bounces, I've been struggling to balance something that looks appealing, whilst still looking realistic.
Obviously a bouncing basketball doesn't really squash or stretch, at least not noticeably to the human eye, but it looks a lot more appealing when it does slightly.
With regards to your questions Wrath;
What principles of animation are you working with in this exercise?
Timing/Spacing. The timing of the peaks/contacts of the bounces, and the interpolation between them for the spacing.
Squash/Stretch, and trying to get a balance between appeal and realism.
Appeal, which is something I'm keeping in mind, but having trouble keeping it 'just enough'
What laws of physics are you dealing with and how do these apply to the principles of animation you're dealing with in this exercise?
Gravity, how quick the ball falls to the ground, how far it bounces back up between bounces, the time it hangs in the air, and the falloff of the bounces as the ball settles.
How would this animation be different for a small rubber ball, a baseball, bowling ball, or a balloon? Why?
Each balls properties (weight, solidity, material) would affect it's relationship with gravity and how high it bounces, and how quick it comes to a rest.
Trippin golf balls, man.
Here's an update;
http://dl.dropbox.com/u/4627207/Animation/Basketball%20Bounce%20w%20SS.mov
Check my animation and drag through and check the squash and stretch. You don't need much but when it's there you'll feel it. Just a frame, and because it's a basketball you should only do a little of it. I don't wanna spoon feed you this but do a couple of different bounces so you can see the contrast better.
What about slow in/out, arcs, and exaggeration?
What about Newton's three laws of motion?
Close, but remember that gravity affects objects equally regardless of mass or size.
http://dl.dropbox.com/u/4627207/Animation/BasketballFalloff.mov
EDIT: Hmm, something isn't right there. It seems AE is skipping frames, and I can't figure out why. Maya output is fine, all 140 frames render out, yet AE skips them on import?
I adjusted the timing some, I like the weight of it now but the last little bit is tricky.
http://dl.dropbox.com/u/4627207/Animation/BasketBallBounceFalloff1.mov
EDIT: Gah timing still way off. Bounces far too quick for a basketball now. I like the weight of it but it may be a bit too bouncy, and not enough hangtime. I will get it!
Let's start with Newton's laws of motion:
http://en.wikipedia.org/wiki/Newton's_laws_of_motion.
Number one. 'An object at rest, stays at rest unless acted on by an outside force' (or more accurately, a body moving at a velocity of zero keeps moving at a velocity of zero, etc). Your ball placed in the air isn't going anywhere on its own free will.
However, we have an outside force. Gravity:
http://en.wikipedia.org/wiki/Equations_for_a_falling_body
Gravity is a constant force which affects all objects the same, regardless of size or mass. Doesn't matter how big it is, or how dense it is, everything is accelerated by gravity in the same way. So for the ball peacefully hovering in the air, gravity as a force begins accelerating it down, faster and faster over time at a predictable rate of acceleration. 9.8 meters per second^2. Technically, the force of acceleration due to gravity on earth changes based on lattitude, altitude, local topology, and geoolgy, but most phsyics just treat it as a constant.
If you were to chart this acceleration out:
http://upload.wikimedia.org/wikipedia/commons/7/7d/Drop_time.jpg
You get an exponential curve known as a parablic arc. Mirror that curve, rotate it around, and ta-da...there's your f-curve that you've been staring at in your graph editor all this time. This is the reason for slow-in/slow-outs, follow through & overshoot, even squash & stretch as principles of animation...Newton's first law of motion and gravity. Moving things want to keep moving and gravity is always working to accelerate things to move downwards. Always keep these things in mind while working on an animation as it's the single most important thing for conveying scale and mass in an animation.
So, given how high it is, you could use this simple formula:
http://upload.wikimedia.org/math/b/e/3/be3f2632bcc189bfe9e21ba96193de63.png To predict exactly how long it would take an object to fall to the ground from a given height. Or you can just do what you think looks right (based on studying reference) because, let's face it, if we liked math we'd be engineers, making the big bucks.
That gets the ball down to the ground, now what? Again, we're back to Newton's first law. The ball wants to continue moving down, because that's where it was going. But now there's this immobile ground thing in the way. Here's where the 2nd and 3rd laws come into play. All of this force, which is generated from the mass of the ball and its velocity given to it by gravity, has to go somewhere. Part of it gets transferred and dissipated into the ground depending on how dense it is. But part of it is absorbed by the ball itself. When the bottom of the ball contacts the ground, it ceases to move forward. But the rest of the ball wants to keep moving forward, like a crowd of molecules trying to rush the stage at a Justin Beiber concert, only real. So the front part stops, the back part keeps going, and because the volume of the ball can't change, it compresses in the direction of its velocity and expands in the other directions.
Squash.
This wave of energy travels through the object, hits the ground itself, and gets deflected back through the object. So you get these overlapping waves of energy moving back and forth through the object, like ripples in a pool, all that energy, dissipating each other. That slow-mo golf ball video is a great example of this. As is this this delicious video:
[ame]
This exchange and diffusion of energy between the collisions of two objets leads up to a single value; a coefficient of restitution. Put simply, how high is the ball going to bounce back up? All of this force generated by the ball falling (2nd law) is given to the ground which promptly says "I'm having none of that mister" and gives most of it right back. So what moves the ball up is all the force generated by gravity pushing the ball down (2nd & 3rd law).
Again, all of this can be figured out formulaically, but for the purposes of fakery in animation we do what looks good. So let's just say your ball has a restitution of 0.75, which is fairly bouncy.
(Have to take a moment here because I pulled 0.75 out of my ass. But then I got curious. What is the real value for a basketball on a hardwood floor? I should probably be more accurate if I'm using a specific example to explain things. So I googled it:
http://www.phy.cmich.edu/people/andy/physics110/book/Chapters/Chapter4.htm My guesses are pretty good.)
If you're initial starting height is 10 units off the ground, then that ball is going to fall (at the rate of gravity), hit the ground, and however fast it was going when it hits the ground is going to begin traveling up at 0.75 times that speed. Then gravity will immediately begin working against that velocity pushing it back down. Here again, we see that exponential velocity change, only this time in reverse or deceleration. Gravity finally works to cancel out any upward velocity the ball has, the ball comes to rest in the air. Where it started from, but at a lower height. Then gravity starts accelerating it back down again and this series of physics events happening over and over again. All governed by consistent laws and formulas.
But we don't really need all of that. All we really need to know is all of this boils down to something fairly simple. Each time the ball bounces, it's 0.75 times as high as the previous bounce and it takes 0.75 times as long. Repeat, repeat, repeat.
Now, all that said, we're not doing physics simulation. We're animatin' dagnabit. And one of the principles of animation is exaggeration. Reality is pretty dull, especially when it's non-reality behaving exactly like reality. So we can exaggerate timing, squash and stretch, velocities...we can bend the laws of physics to suit our artistic purposes. But we have to be careful about how far we bend reality because our little brains are really good at sub-consciously doing physics. The amount of formulation and calculation that's required to reach out and grab a ball flying through the air is pretty damn staggering, but we can do it in fractions of a second without conscious thought. There's some science suggesting that we might actually be capable of sub-consciously seeing into the future, because the math required to predictably catch a thrown ball is too complex to be done by our spongy little brains.
So before the ball hits the ground, we know it's going to squash...because we literally can predict the future in this case. We, the animator, anticipate that squash by stretching the ball, which queues the viewer that something is about to happen to the shape of this ball. That's what anticipation is for in animation, letting the audience know that something fast is about to happen and giving them a general sense of which way that's going action is going so it's easier to follow. The ball hit the ground, gets squashed, and then when the ball bounces back up it's got to return to its normal shape. Rather than just going back to normal, we overshoot and the ball stretches out again, squashes a bit, stretches out, until it eventually resettles back into it's original shape. How much a ball deforms really depends on how dense it is. A ballon filled with water is going to very elastic, so it's going to deform a lot. A bowling ball is very dense polyurethane and doesn't deform much at all in reality...but in an animation we'd probably go ahead and give it a subtle bit anyway, just to liven things up. If we really want to finesse things, we can anticipate (squash) the anticipation(stretch) of the at the top of the parabola.
Understanding and mastering this principle is key because, as I said before, squash and stretch applies to everything...even things that don't deform. So the principle of squash and stretch really goes hand in hand with the principle of overshoot. We're workign with a lot with a simple bouncing ball. Pretty exciting stuff.
There's a reason that 1st term animation mentor rig is a ball with a tail, because working with that very simple rig requires a dealing with all of the principles of animation at the same time. For another study questions, ask yourself "How would each of the principles of animation apply to animating a ball with an attached tail?"
I'll be honest, I'd never studied much of the actual physics behind Newton's laws, and up until now, had never really thought in detail about the hows and whys of them affecting the animation I'm working on. Knowing to keep that in mind when animating anything will be of great help for sure.
You put it across in such a great way too, rather than just saying 'here's the physics, study it'.
With regards to the tail rig. This is a point I want to clear up really, do you think I should start out with the bounce including the deformation as well as the tail?
For some reason, I was under the impression that I should just start out with a bouncing ball, no squash/stretch/no tail, and when I have that down, move on to the deformation, then add the tail. But after taking into account what you've said, it's those things that all play a part in the motion of the ball itself so should I include them from the outset?
Starting with the ball in isolation is fine, if that's what you need to do to get a solid understanding of the timing and slow-in/out. I'm just trying to get you thinking about how these principles of animation came about in the first place and how they apply to what you're working on. Eventually, it will come instinctually, like muscle memory. You won't need to think about ancipation or follow-through, or why you need to do it, you'll just know you do.
http://dl.dropbox.com/u/4627207/Animation/BasketballFalloff2.mov
Better:?
http://dl.dropbox.com/u/4627207/Animation/BasketballFalloff3.mov
the ball also stops bouncing in half the time i expected it to.
interesting reading in this thread, very interesting stuff.
but maybe OP should look at other animations and see where he is going wrong. this is some old school 2d stuff but it applies:
[ame]
and here is a greta ball bounce, look at all the motion he has captured:
[ame]
I could quite easily add a bunch off exagerrated squash/stretch to make mine look exactly like the two examples you linked, but that isn't my goal here. I don't really think either of those video's are anything special.
As mentioned, I'm trying to get a hold of realistic physics, while considering the animation principles. The videos you linked just looked like someone dropped a ball of jello.
And yes, there is a lot of motion in that last vid, but as I did state more than once, I'll move onto to horizontal motions/secondary impacts when I have nailed a vertical bounce.