3D head glossary.

Glossary: MetaHuman, ARKit, LOD, GLB vs FBX

MetaHuman

Epic Games' system for realistic digital humans in Unreal Engine: one shared head topology, a facial rig, strand-based hair (grooms), bodies and clothing. Every MetaHuman has the same mesh layout, so animation made for one works on another. metahuman.com

MetaHuman Creator

The tool where you shape a MetaHuman: conform it to a head mesh, then choose skin, eyes, teeth, grooms, a body and clothing. Since Unreal Engine 5.6 it runs inside the editor; before, it ran in a web browser.

How much MetaHuman costs

MetaHuman comes with Unreal Engine's licence: free for anyone under $1 million in yearly revenue, with Unreal's standard terms above that. Since June 2025, MetaHumans may also be used in other engines and tools. Epic's licence page

Conform

Fitting a MetaHuman's face to a head mesh you bring in, so the MetaHuman takes that shape. When the mesh is already on MetaHuman topology, as FaceNinja's is, conforming keeps every vertex in place. How to do it

Topology

How a mesh's vertices, edges and faces are laid out. Two heads with the same topology have the same number of vertices in the same order, so a rig, blendshapes and textures made for one fit the other.

UVs and UV layout

How a mesh is unfolded flat so a 2D texture can wrap it. Heads with the same UV layout can swap textures: FaceNinja's 4K skin maps use MetaHuman's layout.

ARKit blendshapes

The 52 face movements Apple defined for face tracking on iPhone and iPad, such as jawOpen and eyeBlinkLeft. A head that has all 52 can be driven by an iPhone and by most face-tracking apps. The full list

Blendshape, morph target, shape key

Three names for the same thing: a stored change of the mesh, mixed in by a weight. Unreal and three.js say morph target, Unity and Godot say blend shape, some tools say shape key.

Perfect Sync

A VTubing term for an avatar with all 52 ARKit shapes, so face tracking drives each one directly instead of a few presets.

LOD (level of detail)

Lighter versions of a mesh that an engine swaps in as the object gets further from the camera; LOD 0 is the most detailed. MetaHumans come with several. A FaceNinja file is one detailed level; engines can add lighter ones.

GLB

The binary form of glTF 2.0, the Khronos Group's open 3D format: mesh, materials, textures and blendshapes in one file. three.js, Godot and many viewers read it directly; Unity reads it with a glTF importer package. Khronos: glTF

FBX

An Autodesk format that Unreal, Unity, Maya and most 3D tools read. FaceNinja's FBX is in centimetres, keeps MetaHuman's vertex order and quads, embeds the textures and carries the 52 shapes.

GLB vs FBX

Choose GLB for the web, Godot and glTF pipelines: one open file, in metres. Choose FBX for Unreal, Unity and Maya. A FaceNinja head comes in both, with the same mesh and the same 52 shapes, so you can use each where it fits.

OBJ, STL and PLY

Simpler mesh formats without blendshapes. OBJ comes with its materials and textures; STL is for 3D printing previews, in millimetres, and is open at the neck; PLY carries vertex colours.

Groom

MetaHuman's strand-based hair: head hair, eyebrows, eyelashes, moustache, beard and peach fuzz, chosen in MetaHuman Creator's Hair tab and coloured with Melanin, Redness and Whiteness sliders. FaceNinja names the grooms that match your photo.

PBR maps

Textures that tell a renderer how a surface reacts to light. FaceNinja's four: base colour (Head_Color), normal (Head_Normal, fine relief), cavity (Head_Cavity, pores and creases) and Head_SRMF (specular, roughness, metallic and cavity in one).

Normal map: DirectX or OpenGL

A normal map stores fine surface direction. Its green channel points down in the DirectX convention, which Unreal expects, and up in the OpenGL convention, which glTF uses. FaceNinja's MetaHuman ZIP uses DirectX.

Live Link Face

Epic's free iPhone app that streams face tracking, including the ARKit shapes, to Unreal Engine.