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Dash and Jerry Run the Same Speed! Here's Why.

  • Writer: CJ Paghasian
    CJ Paghasian
  • Jun 21, 2018
  • 4 min read

Updated: Jun 23, 2018

A Body Mechanics Analysis

I saw Incredibles 2 (written and directed by Brad Bird) twice last week: once on the opening night and once the following morning. I absolutely loved every minute of it - great writing, clever plot, and of course, mind-blowing animation. As I was re-watching the film, though, I noticed something.


During the first fight scene, Dash runs to save an old lady from a falling car, where you get a brief front, side, and back view of his run. I went back home, found the clip on Youtube, and started playing through it frame by frame.


Dash saving an old woman in Incredibles 2

When you look at Dash’s run in slo-mo, he almost looks like an ice-skater. His head barely moves, his arms are always in front of him or behind him (and never in between), and his legs never push his body up - only forwards. This isn’t what you normally see in a run cycle.


The Animator's Survival Kit, p.177

Walking and running (and if you’re Buzz Lightyear, flying) is just falling with style. You push your body weight up, then catch it with your legs. There are a few steps in a walk/run cycle:

  • A leg prepares to take weight (Contact)

  • Then it takes the weight (Down)

  • Then it pushes up (Passing/Up)

  • Then back to contact!

In Dash’s run cycle, though, there’s no clear up and down motion. Dash’s head stays stable as he runs, while his body shifts weight like mad. I realized, Dash’s run cycle wasn’t just a normal run cycle only sped up.


This must have been some kind of animation trick. Turns out it was - and it wasn’t the first time it’s been done.


I cracked open my copy of The Animator’s Survival Kit by Richard Williams (director of animation for Roger Rabbit) to look for clues. Here’s what it has to say about designing characters for fast runs:


The Animator's Survival Kit, p.189

As you can see, smaller characters with huge heads and tiny limbs work better for fast run cycles. Why? A short neck and big cranium help keep the head stable. Less head movement lets us see the character more clearly, and provides a main focus point as the rest of the body moves erratically. Smaller legs means there’s less leg to see, so it’s easier to believe the legs are moving as fast as they are.


On the other hand, characters with longer legs need to run slower, because it takes longer to register that long legs are moving. Typically, arms are drawn outstretched in fast-running characters for the same reason that the head is generally stable - it keeps the audience focused on the top of the body.


Animators often move the viewer’s focus to make them believe the unbelievable. Magicians do the same thing.


Traceovers of Dash's run cycle

Just as proof-of-concept, I did some simple trace-overs, tracking Dash’s nose, arm, and leg movement over 10 frames. You can see the fast-runner design at play here. His head only moves when the center of attention must be changed. There’s a little more movement in the arms, but there is an insane amount of movement in the legs.


I took a closer look at Dash’s arms and legs while he runs. As it turns out, they’re combining two age-old animation tricks: the two-drawing run and the three-drawing run. Funnily enough, for a film with a multi-million-dollar budget, these tricks are shortcuts studios forced animators to come up with, when they needed to get animations done as quickly as possible.


It’s hard to get a run cycle faster than in three drawings, because a two-drawing cycle just looks like flickering.



Two-frame cycle. Notice how jittery it looks!

Three-frame cycles register as rotating.

Three frames are just enough to register that there’s a cycling rotation; that the character is about to hit the ground, hits the ground, then lifts off the ground. It’s called a three-drawing run because it takes three drawings for the character to take one step.


Dash’s run follows the three-drawing run... almost perfectly!



The Animator's Survival Kit, p. 192


Dash’s arms, on the other hand, follow a two-drawing. The idea is that you have two drawings: one with a foot in front and an arm in the back, then reverse it in another drawing. All that has to be done is add in-between drawings that are close to one of the two other drawings. So technically, the run happens in four drawings. Dash’s arms stay close to each other for a frame, then swing back, and “freeze” for another two frames.


The Animator's Survival Kit, p. 197

That being said, Dash isn’t very fast for a cartoon character. There are a lot of other characters in animation who follow the short-statured design and have three-drawing runs. Jerry the Mouse, Tweety Bird, Nibbles (the baby mouse), and the Gremlin from Looney Tunes are just three that I could find online. Have a look at these three videos to try finding the three-drawing cycle yourself:

If you’ve never gone through Youtube videos frame by frame before, click the comma (,) to go back one frame and the period (.) to go forward one frame.


An example of a 3-drawing run cycle in traditional animation

People tend to criticize CGI animated films for supposedly being easier to do. But, animators use the same techniques and principles whether they’re animating in 2D, 3D, or VFX. Animators don’t just reinvent the wheel every time they’re given a challenge; they first turn to what the great animators of the past have already figured out, then build from where they left off.


Sometimes, all a new dog needs is old tricks.


Written by: CJ Paghasian

Edited by: Peck Trachsel

All gifs were created with Gif Maker and GIF Speed Changer.


Videos used:

 
 
 

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