Arcs

When throwing a ball, it is common knowledge that it will follow a curved line into the air and then come back down. What may not be common knowledge is that living things also move with this curve. Without this curve, the movements become unnatural, and robotic.

What are Arcs?

This principle explains that everything we do is rounded [1]. The way we are shaped, and even the way we move follows an approximate half circle. When using Arcs in animation, it creates more natural movements and helps to create a flow [1]. Edmond will help explain.

Edmond is showing us some normal movements that we see every day, with the help of some friends. On the left, Edmond is nodding his head up and down. The arrows show where the bottom of his chin would have traveled if he was actually moving. Notice that the arrow is rounded and curved. 

In the middle, you can see an arm waving. You may not notice in every day life, but the movement of the arm is rounded. If you trace the top of the fingers as they move, they do not stay in a strait line. 

On the right is Edmond's friend. You can see that, in the same way as the arm, his tail wags in a curved line. 

We will look for the principle of Arcs in this next example from Disney's Beauty and the Beast [2]:

Be Our Guest

What am I looking at?

• Watch Lumiere (the candelabra/candle stick character) in the beginning, as his arms move around. His movements are very round and fluid. 

• Imagine you have drawn a circle around Lumeiere's left candlestick hand, and that wherever his hand went you would see a line. All of the lines would be loopy and round.

• Notice how all of these curved movements by these objects gives them life and character.

• See the way the plates and treys of food bounce around. Although much of this is due to squash and stretch, they also move in Arcs as they go into the air on each bounce.

When watching videos and searching for this principle, many of the examples are very quick and subtle. However, this principle is rather strait forward. Living things are usually very round, and they also move that way.

How can I use this in my work?

• When looking for this principle in movies, first look for large movements, such as arm waving or running. Once you understand the Arcs in those movements, start to look at smaller ones. Watch very closely

• This principle is mainly used to help keep the animation natural looking. To make sure you are following arks, attach a circle to the point of one of your moving objects (such as an arm, eye, hand, leg, and so on). Watch the circle as it goes through the motion of your action. If it follows a generally curved path, then it should be natural looking.

Sources:

[1] Atkinson, David. Animation Notes #5 Principles of Animation.  Retrieved from http://minyos.its.rmit.edu.au/aim/a_notes/anim_principles.html.

[2] Ashman, H., Hahn, D., Lasseter, J., McArthur, S., (Producers), Trousdale, G., & Wise, K., (Directors). (1991) Beauty and the Beast. United States: Walt Disney Pictures.