Is there a name for this kind of composited sprite animation technique?

Question

Character avatars composed of different sprites for each component (arms, legs, head) connected together through a series of joints seem to be trending lately. For example, Scrolls, Candy Crush (in the cutscenes) and the iOS Agricola game.

This system allows the characters to have movements without having to author each frame on a sprite and can look much smoother.

For example, see how the characters seem to breathe in this video? I've checked the game files, they are indeed composed of static parts, linked together through some kind of skeleton.

What is this technique called?

Answer 1

You've pretty much already hit on the terms. What you're describing is just a variation on skeletal animation, constrained to 2D.

This allows a "skeleton" to be defined onto which various sprites representing individual body parts can be mapped and then transformed via translation, rotation or scaling manipulations (the last is probably how you'd implement the 'breathing' appearance).

An animation is represented as a series of transforms to particular bones of the skeleton, which are mapped at runtime to translations on the actual sprites being used to create the character composite.

You can search this site for questions about 2D skeletal animation for more details.