Concept

Skeleton

A skeleton is the hierarchical bone structure of a 3D character, driving mesh deformation through skin weights when posed or animated.

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What is a Skeleton in 3D Animation?

A skeleton in 3D animation is a hierarchical chain of bones, each with a position, orientation, and parent-child relationship, that forms the internal armature of a character and drives the deformation of the surrounding mesh through skin weights. Moving a bone propagates the transformation down the hierarchy to all child bones.

How it works

A humanoid skeleton typically includes bones for the spine, pelvis, limbs, hands, and head, organized in a tree hierarchy rooted at the hips or pelvis. Animators pose the skeleton by rotating bones, and the skin weights determine how the mesh follows. Inverse kinematics (IK) lets animators position an end effector, such as a hand or foot, and have the chain of parent bones solve automatically. Skeletons are stored in FBX and GLB files alongside the mesh and can be retargeted to share animations across different characters with compatible hierarchies.

Skeleton vs control rig

Hips or pelvis in most humanoids

Root joint

4 joints per vertex per set (glTF 2.0)

Skin influences

15 required bones

Unity Humanoid avatar

Skeleton

Control rig

What it is

Hierarchy of bones bound to the mesh

Controllers and constraints that drive bones

Deforms the mesh

Yes, through skin weights

No, it only moves the skeleton

Exported to engines

Yes, in FBX and GLB with the mesh

Usually stripped; motion baked to bone keys

Built by

Rigger or auto-rigging tool

Rigger, tailored per production

Animator works on

Rarely directly

Mostly: IK handles, switches, shapes

Retargeting

Joint mapping between two skeletons

Rebuilt or re-mapped for each new rig

Engines consume the skeleton, not the control rig: animation is baked to bone keys on export. Build the control rig for the animator and keep the skeleton clean and hierarchical for the engine and for retargeting.

In Meshy Auto-rigging builds a humanoid skeleton for a generated character in minutes, and the rigged FBX or GLB export carries that joint hierarchy into Blender, Maya, Unity, or Unreal for control-rig work or retargeting.

Use cases

Driving character animation by posing a hierarchical bone structure
Retargeting motion-capture data onto a custom character skeleton
Enabling inverse kinematics for foot planting and hand reaching in games

3D Animation 3D Avatars VFX

Last updated September 14, 2026

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Other terms

Rigging Auto-Rigging Weight Painting Inverse Kinematics Forward Kinematics Bone Skinning Blend Shape 3D Animation

Frequently Asked Questions

A skeleton is the bone hierarchy itself — the structural armature. A rig is the complete control system built on top of the skeleton, including IK handles, control curves, constraints, and custom attributes that make the skeleton easy for animators to pose. The skeleton is the foundation; the rig is the interface.

A minimal game-ready humanoid skeleton typically has 50 to 70 bones covering the spine, limbs, hands, and head. Full facial rigs can add dozens more. Unity's Humanoid avatar system maps to a standard set of 15 required bones and several optional ones.

Yes, if the characters share a compatible bone hierarchy. Animation retargeting maps the source skeleton's bone rotations onto the target skeleton, allowing motion-capture data or hand-keyed animations to drive different characters. Unity and Unreal Engine both support retargeting for humanoid skeletons.

A bone hierarchy is the parent-child tree that organizes a skeleton, usually rooted at the hips or pelvis. Moving a parent bone transforms all of its children, so rotating the upper arm carries the forearm and hand with it. This hierarchy is what makes posing a character intuitive and physically plausible.

They refer to the same thing in different software. Armature is Blender's name for the bone structure, while skeleton is the more common term in Maya, Unity, and Unreal. Both describe the hierarchy of bones that drives mesh deformation.

The root bone sits at the top of the hierarchy and defines the character's overall position and orientation in the scene. Moving the root moves the whole character, which is essential for placing and animating locomotion. Game engines rely on a consistent root for movement and root-motion animation.

The rest pose, or bind pose, is the default posture in which the mesh was bound to the skeleton, commonly a T-pose or A-pose. Skin weights are calculated relative to this pose, and animation transforms are measured as deviations from it. Rebinding at a different pose recalculates the weights.

Both formats store the bone hierarchy, each bone's transform, and the skin weights that bind the mesh to the bones, alongside the geometry. This lets a single file carry a fully rigged character. FBX is standard for engines and animation tools, while GLB is preferred for web delivery.

Meshy builds a standard humanoid skeleton with a clean hierarchy compatible with Unity's Humanoid avatar system and Unreal Engine's retargeting tools. The skeleton exports in FBX alongside the mesh and skin weights, ready for animation and retargeting.

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Skeleton

What is a Skeleton in 3D Animation?

How it works

Skeleton vs control rig

Use cases