Why Animators Need Stepped Curves

Stepped Curves in Maya

Why do animators need to work in Stepped Curves? Many animators resist using Stepped Curves when they first start learning animation. Spline Curves feel much more intuitive, because Maya does the interpolation for you.

However, for most character acting shots, and any shot which is basically pose-to-pose, Stepped Curves are a much more powerful tool, and one which it is very important for animators to master.

Robots

What are Stepped Curves?

Stepped Curves in Maya allow the animator to play back their work as a series of still poses, much like in the old days of hand-drawn animation.  The idea is to take your thumbnail sketches and turn these into poses in Maya, then play them back as a series of still images that tell the story of the shot. This is called "Rough Blocking".

Block Out Your Shot

The idea is to block out your shot, pose by pose, making sure that the story of the shot is told in a series of distinct poses. When these poses are played back as a series of still images, we should be able to tel what is going on in the shot.

When to Spline?

The next stage - knowing when to spline your curves, is harder to get right. In general, you want to delay pressing "Spline" for as long as possible. Instead, create breakdown poses between your key poses. To do this, we recommend downloading a free plugin for Maya called "The Tween Machine".

The Tween Machine
The best (and quickest) technique for this process is to use the Tween Machine, a free plugin for Maya.
The Tween Machine helps the animator to break your key poses down into Extremes, Breakdowns and - finally - even In-Betweens. 

Keys, Extremes, Breakdowns and In-Betweens
What are Keys, Extremes, Breakdowns and In-Betweens? If you don't already know, then watch the video below to understand these basic animation concepts.


Using the Tween Machine
Using the Tween Machine, you can break your poses down to Keys, Extremes and Breakdowns, ending up with keyframes on your control curves approximately - though not necessarily exactly - every four frames.

If your animation is working "on fours" (ie a pose roughly every four frames), you should be able to get a pretty good idea of whether it is working or not. If it is working, then you can now spline your curves, knowing that the final animation - while it will still likely need some tweaks - should come out OK.

The danger most student animators face is that they tend to hit spline too too early, before all the breakdowns are really worked out. Doing this, you make Maya do too much of the work for you, and the result comes out mushy and "spliney".

Tween Machine Video
To see more about how to use the Tween Machine, read this blog post, and watch the video below.

Planning Animation

Using Live Action to Plan Animation

The key to successful animation is to plan it properly. This means doing rough thumbnail sketches to plan out your work. Thumbnail sketches show the key poses in the shot, which correspond to the "accents" within the lines of dialogue. 

Links

To see some examples of how to plan animation (including how to use thumbnail sketches and live action), follow these links:

• Medusa Thumbnails by Milt Kahl
• Why thumbnail sketches need facial expressions
• Thumbnail sketches by Pixar's Victor Navone
• Thumbnailing Mrs Copperbottom from "Robots"
• Thumbnailing "Boog" from "Open Season"
• How to Use the Tween Machine
• How to Animate a Dialogue Shot
• How to Plan a Pantomime Shot
• How to Plan a Creature Animation Shot
• How to Use Live Action Reference to Plan Animation

To find out more about Animation Apprentice, click here for a link to Frequently Asked Questions. To sign up for our next classroom at Animation Apprentice, follow this link.