Learn the principles behind character animation and how to use them for different results.
Preparation
Step 1: Acquire References
Whenever you animate you need a reference. It can be a video, an image, a friend performing in front of you, another animation or quite often it can be a memory of someone moving. Even if you’re not using a reference consciously you are using your past experiences as a reference, you animate what FEELS right.
I recommend using other references than just your memory since our memory is subjective. What you remember is flavored by how you perceived the situation. For example two people attending a lecture with a teacher that has a rather calm and relaxed way of moving his hands while he talks can have immensely different impression of how it was:
- Person A: This person doesn’t really like the teacher as he gave him an F in the last course. This person think that his body language is very dull and slow.
- Person B: This fellow on the other hand has a very keen interest in the subject and has read all the articles the teacher has published and admires him, he will think his body language is creative and harmonic.
These kids have witnessed the same motions but will remember them in two completely different ways. There are a lot of factors that will affect how you remember things, your mood, the weather, who you’re with, etc, etc.
Another reason for recommending references other than your memory is that you will see things you would never have figured out on your own; small details that give the shot that little extra that makes it come alive. However, we don’t always have time to look at references as we’re in a business where short deadlines are common so building a good memory bank of references is NOT a thing that is bad. Being able to simply feel what is good motion is what makes a person a good animator.
Step 2: Analyze
Once you have acquired some reference material that fit your needs it’s time to analyze it. For reference material for this tutorial I filmed myself throwing a small stone:
And here are the keyframes I’ve picked out:
We analyze the references so that we can find information that will help us make an interesting and eye-pleasing motion, simply copying the keyposes will not be enough (unless you’re going for a rotoscoped look of course).
So what are we looking for? The answer to this is simple: we’re looking for anything that will add depth and life to the motion. Some examples of things to look for are:
- Blinks
- Subtle eye motions
- Arcs
- Opposing action
- Timing of the motion
- Small steps to adjust the center of mass
- Which foot is carrying most of the weight
Step 3: Find the Line of Action
The first thing we will do is to look where our ‘line of action’ should go. The basic concept of line of action is that by giving your poses an even flow you increase the readability of them, making them easier for the viewer to look at (more on this later).
So how do you find the line of action? Well, first of all we need to understand that all motions are based on arcs. If you extend your arm straight out and wave it around it will make arcs in the air with your shoulder as the pivot point. Same if you bend your arm, the elbow will become the pivot point. This is true for all our joints. So once we know this we can start looking for arcs.
This is pretty much the main arc of the throw. There are of course arcs for every single joint but this one is the main action and the one we need for the line of action. Because as we said, the line of action is there to help the viewer read the image, or in other words, read the action.
Placing the line of action can be tricky, in this case it’s rather easy since our action is very straight forward and we have a clear arc, which is not always the case.
Anyway, let’s have a look at the first keyframe (frame 8 in the reference). Our character has his feet planted on the ground and is reaching backwards to prepare for the throw (some proper anticipation right here! More on this later). We create an arc through the body.
The next two keyframes (frames 16 and 19) are pretty straight forward and the line of action is not changing much.
Frame 21 has the most important change in the line of action since this is right where the action is happening, the line of action works like a whip here (the line of action often works like a whip or wave) and will help the animation create the feel that the stone is launched forward.
In the last two keyframes (frames 24 and 32) the line of action comes to a neutral rest as the power of the motion diminishes.
Now that we have the line of the action let’s take a quick peek at how it looks exaggerated and animated:
Nice, that line alone could already be throwing a rock!
Step 4: Opposing Actions
Opposing actions are in short terms two or more motions that are going in different directions; they oppose each other. It’s usually used in dialog to break a character up so that it doesn’t look as mechanical.
As you can see in the image above the character is slamming his fist into his hand as well as slightly lifting his head, by slightly moving the head in the other direction we get a lot more tension in the fist, also if he move his head into the lower position as he is raising his fist we get an opposing action there as well and at the same time we get some nice anticipation!
But it has more uses than just in dialogs, for example you can use it too keep a character’s center of gravity balanced, which it does in this motion.
In the first keyframe the left arm moves out from the body as the right arm reaches back in anticipation for the throw. This helps with the anticipation as well as center the center of gravity. On the second keyframe the arms switch direction as they start to propel the stone forward. The third keyframe is pretty much the same as the second. On the fourth keyframe the arms have just passed their highest velocity, which is the point where the stone is released. On the two last keyframes the arms have lost most velocity and come to a rest.
Throughout the whole motion the left arm is catering the right arm (throwing arm) with two things, balance and power. By moving the arm backwards as we’re throwing the pivot point of the throw and the center of mass gets closer together and it’s easier to reach a high velocity. See image below for illustration of the principle.
In the first figure the weight and the pivot point are separated and you will need a lot of force to get the contraption to accelerate. While in the second figure the weight and the pivot point are in the exact same spot, now you will just need a little push to get the contraption moving.