Brendan's Bouncing Ball Lecture


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Bouncing Ball, More Squash


Another common mistake in trying to add more weight is thinking that by adding more squash to your characters they will appear heavier. But, as we can see in this animation, this is not the case. The ball doesn’t look heavier, it just begins to look silly.

Bouncing Ball, Extreme Squash


This is especially apparent when we take it to an extreme as in this case. This is very entertaining, and this level of squash would be acceptable if we are animating a silly character, such as Roger Rabbit. But if this were done to a more sophisticated character, such as Mowgli from the Jungle book, he would not only look stupid but the audience would not have the same emotional connection with him. As the great Chuck Jones said -

“You can have fun with silly putty but nobody will ever love it or care what happens to it.”

Which is to say, it’s a lot of fun to distort characters to great extremes but if you’re animating a character, that you want the audience to care for, you have to be careful not to squash them too much as that will destroy that connection your viewer has with the character.
At the same time, you have to walk a fine line, because you don’t want to be too conservative and make your characters look stiff and lifeless.

Bouncing Ball, Tail Added


A good way of adding extra life to straighter characters, without squashing them, is with drag and follow through. In this animation I’ve added a simple tail and you can see that, with just this, I’m getting a lot more movement and life out of my ball. This is something you can really push in your animation and it will always help to improve it.
Often, your primary animation can be quite subtle but by pushing your drag and follow through you’ll get a lot more for your money. Milt Kahl was a master of this, some of his animation when the individual drawings are viewed appears almost excessively floppy, yet it still works brilliantly. So, when animating a character always look for things you can drag and follow through such as hair, clothes, fur, ears, hands, etc. And if you are designing the character yourself, adding appendages or accessories that can be dragged is a good idea.

Bouncing Ball, tail, Hair and Eye


As crude as this is, hopefully you can see that by adding more drag and follow through you start to, firstly create something more entertaining, and also remove it from the boring bouncing ball and create a character.

Bouncing Ball, Richard Williams' Version


Before we go on to look at this idea further, I want to quickly look at another way of doing the bouncing ball. There are many different, and equally valid ways of doing a bouncing ball, this is the way suggested in The Animator's Survival Kit by Richard Williams.
The way it differs from the previous, Frank Thomas, bouncing ball is quite subtle. The two drawings at the bottom are reversed so after the gap, we go to a stretched drawing that is in contact with the ground, then to our squashed drawing. This, according to the book, helps us sense the change of shape in the ball.
This is true, we can now feel the ball changing shape as it contacts the ground, but this is in detriment to the weight of the ball. We now have the ball effectively cushioning in to the ground which has less impact than going from one extreme to another. Also, the ball now pings up off the ground instead of the subtle feeling of acceleration we had before.
I'm not going to say Richard William's ball is wrong but it's not perfect, by changing these frames you do gain something but at the loss of something else. However, knowing these variations is always useful in case we want to achieve this different effect.

Walking Legs


Let's now see how the bouncing ball applies to an animated character. Here are some legs I’ve animated walking, but at the moment they look very mechanical. They're also severely lacking life, and are completely devoid of weight.

Walk with Bouncing Ball Applied


In this animation I’ve added the vertical animation from our bouncing ball (I’ve put the ball beside the hips so you can see it). The weightless and lifeless feeling we had before has now gone.

Also notice I’ve put the lowest point of the hips 2 frames after the foot contacts the ground. And similarly the highest point of the hips is not exactly at the crossover but rather 2 frames after. The number of frames after the foot contacts the ground until the hip's lowest point will vary, but this is important to give the illusion of momentum. After all, the hips are falling at the point the foot makes contact with the ground and it takes a moment for the leg to catch the weight of the body.

Walk with Another Bouncing Ball


In this animation I've copied the vertical animation (ie. the bouncing ball) of the hips onto another ball and offset it by 1 frame which will hopefully make more sense in the next movie when ...

Walk with 2 Bouncing Balls

... I add another ball above this one, with the same animation again, but offset by another frame.

Now, hopefully you can see the effect created, the three balls represent the three body masses of a typical biped character - hips, ribcage and brain-case. The bouncing balls start to work in concert together and we get a very fluid follow through effecting the whole body yet the motion still has a sense of weight.

This is really the whole point, by applying the bouncing ball to body parts we can be confident they will appear weighty and by offsetting them we can achieve a fluid action.

We could apply this theory to many actions, for example, a vigorous point - the hips could drop down first, then the elbow, then the hand, and finally the finger. All of these maintaining the bouncing ball spacing we’ve learnt, but offset. And we can be sure of getting a very fluid, powerful and weighty action.

What we can’t squash is just as important as what we can. As I’ve already mentioned, the balls represent the three body masses, the hips, ribcage and brain-case. These masses can, to a degree, often be separated and given their own weight and movement. These parts are also the solid parts of the body and, if your trying to achieve a sense of realism, should not visibly distort (ordinarily). Squash and stretch should be added to the parts of the body that can distort – hair, ears, tails, muscle, fat, and the spine. And this mixture of stiff and flexible parts of the character will give us a sense of contrast within the character.

Although, we have to be careful about how much we squash and stretch the spine. It can help achieve a greater sense of squash and stretch in the spine by bending it. Although this character currently doesn't have a spine, it’s easy to sense that when the hips initially drop and the chest is left behind we would have the spine stretched out into a straight line, then a few frames later when the chest is at it’s lowest point the spine would be at a ‘squash’, shorter and curved over. And this shape change - going from a straight to a curve is always desirable in animation – you can see we already have it in the legs.

Walk with Nose


Now, as before, it helps to add some drag and follow through to your bouncing balls. You can see that just adding this small touch really helps to add life and weight to the animation.



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© Brendan Body 2008