What is The Euler Filter, and How Do You Use It?

Dr Leonhard Euler by Jakob Emanuel Handmann. 
Image: Wikimedia Commons

Look under the Curves menu in the Graph Editor in Autodesk Maya and you will see a button marked Euler Filter. Not knowing what it does (or even how to pronounce it), you have probably never used it - why would you? But don't be deceived by the odd name.

The Euler Filter is a very useful tool in Maya, one which can solve - almost magically - some of the most common problems we get in the rotations of curves, problems which can seriously mess up your character animation.  If the rotations on your character's arms are going wild, and no amount of keyframing seems to help - you probably need a little help from Dr Euler.

What is the Euler filter?
It is a tool used to unscramble rotation curves in Maya.

When should you use it?
Use it when you are getting weird rotations in your curves. Most commonly this occurs when you are animating a character's arms, especially if there is a lot of motion, say if the character is jumping, or throwing something. If your rotations are wildly crossing one another in the Graph Editor, and you can't seem to make the motion smooth and appealing, you may need assistance from Dr Euler.

Dr Euler even had his own postage stamp.
Image: Wikimedia Commons

Why the funny name?
The Euler filter is named after Dr Leonhard Euler, a very clever Swiss mathematician. His name is pronounced "Oiler", not "Yuler" - in case you were wondering.

And yes, he has a Wikipedia page, so you can find out more about his life and work. It's all maths though - no animation.

How Does the Euler Filter Work in Maya?
It works with a single click of your mouse or Wacom pen.  Find the Euler Filter under Curves>Euler Filter. The filter resets the rotational curves so that the values do not exceed 360 degrees.  It is a very elegant solution (when it works) and is far less work than trying to fix your curves frame by frame, one keyframe at a time.

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