skeletanimation

Skeletal animation, also known as bone-based animation, is a computer graphics technique in which a character mesh is deformed by a hierarchical set of bones, or a skeleton. The skeleton defines the structure of joints and bones, and a rig provides controls for animators. The mesh is bound to the skeleton through skinning, where each vertex is assigned weights that determine how much influence each bone has on it as bones move.

Two core concepts are forward kinematics and inverse kinematics. In forward kinematics, rotations are applied along the bone chain from the root outward. In inverse kinematics, software solves for joint angles to place an end effector (such as a hand or foot) at a target position, which is useful for natural posing and animation of limbs. The rig often includes constraints and control handles to simplify posing, looping, and retargeting.

Typical workflows involve modeling, rigging, skinning, animation, and export. Animation data is stored as bone transforms over time, and skin weights per vertex encode deformations. Data may be compressed and exported to formats such as FBX, COLLADA, or GLTF, and used in game engines (Unity, Unreal) or CGI software (Maya, Blender).

Skeletal animation is efficient for animating complex characters because it separates articulation from geometry, enabling reusable rigs and motion capture integration. Limitations include potential volume loss during extreme bending and skinning artifacts; solutions include dual quaternion skinning, corrective blend shapes, and volume-preserving rigs. Advanced topics include retargeting to different rigs, clip blending, and physics-assisted animation.