A rigging artist adds a skeleton-like structure of connected bones to the inner workings of a 2D or 3D model using model rigging software. For a character, there may be arm and finger bones, a spine, and so on, but non-character models such as vehicles, trees, and other objects can be rigged too.
Animators can use keyframing to move the rigged bones’ position, rotation, etc., thus animating the rigged model. The connected bones of a rigging are in a hierarchal relationship to each other, which helps simplify the work of animation. For example, the rotation of a shoulder joint will affect the movement of the upper arm, elbow, forearm, etc.
When working with 2D rigging animation software, the rigged bone structure and movements will be simpler for a 2D character, but the concept is essentially the same as when rigging more complicated and flexible 3D characters in 3D rigging software.
Rigging is one of the first steps in skeletal animation. There are other types of animation, but 3D skeletal animation has become ubiquitous in every medium using animation, such as movies, TV, video games, and advertising.
Rigging artists may create hundreds of control points for a complex model based on how they want the character to move. However, taking additional steps in character rigging software will ensure more realistic animations. The technique of weight painting interprets how vertices within the larger 3D mesh of a character model will respond to the movements of discrete bones in a rig. Model rigging software can apply weight painting automatically, but riggers should fine-tune the automated weight scale for best results.
Character rigs also often need inverse kinematics, which is a tool in rigging software that keeps jointed bone clusters like arms and legs pointed correctly when a character, for example, walks or throws something. Finally, realistic movement requires that the artist applies some constraints or restrictions to some of a character rig’s bones, so that, for instance, a certain bone can only move in one direction.
With all the work required just to set up a character model for animation, it’s nice to know that rigging software can save and copy entire riggings to be reused or modified for similar characters, the same way that animations can be reused or modified to save time.