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Version: Current (v5.0)

Unified Expressions


Still under construction

This reference document is still being updated. Changes are subject to happen discretionally.

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Summary

Unified Expressions is an open source face expression standard used as the tracking standard for VRCFaceTracking and the expression shape standard for avatars. It is fully compatible with existing face tracking shapes from other expression standards such as ARKit / PerfectSync, SRanipal, FACS, and others.

This document contains information about Unified Expressions, including the overall usage of it and references for shapes to use on avatars.


Unified Expressions Overview

Why use Unified Expressions?


Unified Expressions is a high fidelity and adaptable standard.

Unified Expressions is a robust face expression standard that avatars can use to create face tracking shapes, and gives avatar creators a huge amount of choice in how they want to best adapt tracking behaviors to their avatars.

Unified Expressions is designed to unify all shape and tracking standards.

VRCFaceTracking uses Unified Expressions as the bridge between tracking interfaces and avatar shapes. This allows for a huge amount of tracking customization, specialization, and backwards compatibility for many existing VRCFaceTracking avatars.

It is able to use shapes designed for other tracking standards and provide tracking transformations to work with different shape standards such as ARKit, FACS, SRanipal, and others.

Building an avatar for Unified Expressions also means that you will only have to build a single set of shapes for an avatar that will work nearly identically across different face tracking devices and interfaces. Unified Expressions shapes are untied to any device or interface implementation; the shapes are instead wholely reliant on anatomical basis to give grounding to the shapes.

Unified Expressions is formatted to be able to be improved over time.

The Unified Expressions standard is also formatted in a heirarchy of fidelity, powered by VRCFaceTracking's dynamic parameter system, allowing avatars to adopt either more simplistic or more complex tracking behaviors out of the expression shapes. Unified Expressions was built out this way in order to retain backwards compatibility with future revisions and to allow the standard to evolve over time (if and when the need for updating arises).

Unified Expressions Best Practices


Unified Expressions is similar to most other facial expression standards available, with the addition of many additional transformed expression shapes provided that allow avatars to highly specialize or even optimise their face tracking setups to work best with their avatars.

Unified Expressions has many Blended shapes available for use on avatars that can affect tracking.

Blended shapes can be used to simplify, combine, or alleviate both shape creation and offer more simplified tracking behavior on avatars. Creators should familiarize with all available shapes and decide what shapes work best on certain avatars.

Unified Expressions Shapes


This section contains documentation for all currently implemented Unified Expressions shapes available for use in VRCFaceTracking on avatars. These are all the shapes contained under the Unified Expressions shapes umbrella:

These are shape references, not parameters.

For VRCFaceTracking specific avatar parameters please refer to Avatar Parameters, which lists the parameters that are intended to control these shapes.

Documentation still actively in development

Information may be sparse, and we are working to incorporate features that allow us to give highly detailed explanations in the future.

To see what that might look like, hover over this text!

Base Shapes

The following table contains all base shapes available in Unified Expressions.

Decide what shapes are best for your avatar!

Unified Expressions' Base Shapes are heavily based upon highly technical facial anatomies and, while this might be good for achieving highly detailed face tracking (and highly recommended), there may be cases where you might prefer to use more simplified or easier to create shapes. This could be to suit an avatar's style, simplify tracking behavior, or to quickly develop shapes that will just work.

Many of the following shapes are able to be discretionally mixed and matched together! Please refer to Blended Shapes for officially supported simplified shapes for avatars. Thanks to VRCFaceTracking's powerful parameter system, Unified Expressions can be organically adjusted to suit your avatar's needs.

Please read through all available shapes and decide what is best for your avatar.

Reference
Reference Image
Basis
ReferenceNameDescription
Reference ImageEyeLookOutRightRight eye looks out.
Reference ImageEyeLookInRightRight eye looks in.
Reference ImageEyeLookUpRightRight eye looks up.
Reference ImageEyeLookDownRightRight eye looks down.
Reference ImageEyeLookOutLeftLeft eye looks out.
Reference ImageEyeLookInLeftLeft eye looks in.
Reference ImageEyeLookUpLeftLeft eye looks up.
Reference ImageEyeLookDownLeftLeft eye looks down.
Reference ImageEyeClosedRightCloses the right eyelid.
Reference ImageEyeClosedLeftCloses the left eyelid.
Reference ImageEyeSquintRightSqueezes the right eye socket muscles.
Reference ImageEyeSquintLeftSqueezes the left eye socket muscles.
Reference ImageEyeWideRightRight eyelid widens beyond relaxed.
Reference ImageEyeWideLeftLeft eyelid widens beyond relaxed.
Reference ImageEyeDilationRightDilates the right eye pupil
Reference ImageEyeDilationLeftDilates the left eye pupil
Reference ImageEyeConstrictRightConstricts the right eye pupil
Reference ImageEyeConstrictLeftConstricts the left eye pupil
Reference ImageBrowPinchRightRight eyebrow pinches in.
Reference ImageBrowPinchLeftLeft eyebrow pinches in.
Reference ImageBrowLowererRightOuter right eyebrow pulls down.
Reference ImageBrowLowererLeftOuter Left eyebrow pulls down.
Reference ImageBrowInnerUpRightInner right eyebrow pulls up.
Reference ImageBrowInnerUpLeftInner left eyebrow pulls up.
Reference ImageBrowOuterUpRightOuter right eyebrow pulls up.
Reference ImageBrowOuterUpLeftOuter left eyebrow pulls up.
Reference ImageNoseSneerRightRight side face sneers.
Reference ImageNoseSneerLeftLeft side face sneers.
Reference ImageNasalDilationRightRight side nose canal dilates.
Reference ImageNasalDilationLeftLeft side nose canal dilates.
Reference ImageNasalConstrictRightRight side nose canal constricts.
Reference ImageNasalConstrictLeftLeft side nose canal constricts.
Reference ImageCheekSquintRightRaises the right side cheek.
Reference ImageCheekSquintLeftRaises the left side cheek.
Reference ImageCheekPuffRightPuffs the right side cheek.
Reference ImageCheekPuffLeftPuffs the left side cheek.
Reference ImageCheekSuckRightSucks in the right side cheek.
Reference ImageCheekSuckLeftSucks in the left side cheek.
Reference ImageJawOpenOpens jawbone.
Reference ImageMouthClosedCloses mouth (in relation to JawOpen).
Reference ImageJawRightPushes jawbone right.
Reference ImageJawLeftPushes jawbone left.
Reference ImageJawForwardPushes jawbone forwards.
Reference ImageJawBackwardPulls jawbone backwards.
Reference ImageJawClenchFlexes jaw muscles.
Reference ImageJawMandibleRaiseRaises jawbone.
Reference ImageLipSuckUpperRightUpper right lip part tucks in the mouth.
Reference ImageLipSuckUpperLeftUpper left lip part tucks in the mouth.
Reference ImageLipSuckLowerRightLower right lip part tucks in the mouth.
Reference ImageLipSuckLowerLeftLower left lip part tucks in the mouth.
Reference ImageLipSuckCornerRightRight lip corner folds into the mouth.
Reference ImageLipSuckCornerLeftLeft lip corner folds into the mouth.
Reference ImageLipFunnelUpperRightUpper right lip part pushes into a funnel.
Reference ImageLipFunnelUpperLeftUpper left lip part pushes into a funnel.
Reference ImageLipFunnelLowerRightLower right lip part pushes into a funnel.
Reference ImageLipFunnelLowerLeftLower left lip part pushes into a funnel.
Reference ImageLipPuckerUpperRightUpper right lip part pushes outward.
Reference ImageLipPuckerUpperLeftUpper left lip part pushes outward.
Reference ImageLipPuckerLowerRightLower right lip part pushes outward.
Reference ImageLipPuckerLowerLeftLower left lip part pushes outward.
Reference ImageMouthUpperUpRightUpper right part of the lip pulls up.
Reference ImageMouthUpperUpLeftUpper left part of the lip pulls up.
Reference ImageMouthLowerDownRightLower right part of the lip pulls up.
Reference ImageMouthLowerDownLeftLower left part of the lip pulls up.
Reference ImageMouthUpperDeepenRightUpper right lip part pushes in the cheek.
Reference ImageMouthUpperDeepenLeftUpper left lip part pushes in the cheek.
Reference ImageMouthUpperRightMoves upper lip right.
Reference ImageMouthUpperLeftMoves upper lip left.
Reference ImageMouthLowerRightMoves lower lip right.
Reference ImageMouthLowerLeftMoves lower lip left.
Reference ImageMouthCornerPullRightRight lip corner pulls diagonally up and out.
Reference ImageMouthCornerPullLeftLeft lip corner pulls diagonally up and out.
Reference ImageMouthCornerSlantRightRight corner lip slants up.
Reference ImageMouthCornerSlantLeftLeft corner lip slants up.
Reference ImageMouthFrownRightRight corner lip pulls down.
Reference ImageMouthFrownLeftLeft corner lip pulls down.
Reference ImageMouthStretchRightRight corner lip pulls out and down.
Reference ImageMouthStretchLeftLeft corner lip pulls out and down.
Reference ImageMouthDimpleRightRight lip corner is pushed backwards.
Reference ImageMouthDimpleLeftLeft lip corner is pulled backwards.
Reference ImageMouthRaiserUpperRaises and slightly pushes out the upper mouth.
Reference ImageMouthRaiserLowerRaises and slightly pushes out the lower mouth.
Reference ImageMouthPressRightRight side lips press and flatten together vertically.
Reference ImageMouthPressLeftLeft side lips press and flatten together vertically.
Reference ImageMouthTightenerRightRight side lips squeeze together horizontally.
Reference ImageMouthTightenerLeftLeft side lips squeeze together horizontally.
Reference ImageTongueOutTongue visibly sticks out of the mouth.
Reference ImageTongueUpTongue points up.
Reference ImageTongueDownTongue points down.
Reference ImageTongueRightTongue points right.
Reference ImageTongueLeftTongue points left.
Reference ImageTongueRollSides of the tongue funnel, creating a 'hotdog' shape.
Reference ImageTongueBendDownTongue arches up then down inside the mouth.
Reference ImageTongueCurlUpTongue arches down then up inside the mouth.
Reference ImageTongueSquishTongue squishes together and thickens.
Reference ImageTongueFlatTongue flattens and thins out.
Reference ImageTongueTwistRightTongue tip rotates clockwise, with the rest following gradually.
Reference ImageTongueTwistLeftTongue tip rotates counter-clockwise, with the rest following gradually.
Reference ImageSoftPalateClose¹Inner mouth throat closes.
Reference ImageThroatSwallow¹The Adam's apple visibly swallows.
Reference ImageNeckFlexRight¹Right side neck visibly flexes.
Reference ImageNeckFlexLeft¹Left side neck visibly flexes.

1: Unused by all interfaces.

2: Physically 'impossible' from normal anatomy.

Blended Shapes

The following shapes blend together the Unified Expressions Base Shapes above into more simplified shapes. Many of these align with tracking interfaces, other face tracking standards, and generalized expressions.

Unified Expressions is designed to be flexible

Many Base Shapes may be able to be discretionally mixed and matched together that are not otherwise listed here. The listed shapes below also have direct tracking transformations available in VRCFaceTracking.

ReferenceNameDescription
Reference ImageEyeClosedCloses both eye lids.
Reference ImageEyeWideWidens both eye lids.
Reference ImageEyeSquintSquints both eye lids.
Reference ImageEyeDilationDilates both pupils.
Reference ImageEyeConstrictConstricts both pupils.
Reference ImageBrowDownRightPulls the right eyebrow down and in.
Reference ImageBrowDownLeftPulls the left eyebrow down and in.
Reference ImageBrowDownPulls the left eyebrow down and in.
Reference ImageBrowUpRightRight brow appears worried.
Reference ImageBrowUpLeftLeft brow appears worried.
Reference ImageBrowUpBrows appear worried.
Reference ImageNoseSneerEntire face sneers.
Reference ImageNasalDilationBoth nose canals dilate.
Reference ImageNasalConstrictBoth nose canals constrict.
Reference ImageCheekPuffPuffs both cheeks.
Reference ImageCheekSuckSucks both cheeks.
Reference ImageCheekSquintRaises both cheeks.
Reference ImageLipSuckUpperTucks in the upper lips.
Reference ImageLipSuckLowerTucks in the lower lips.
Reference ImageLipSuckTucks in the upper and lower lips.
Reference ImageLipFunnelUpperFunnels in the upper lips.
Reference ImageLipFunnelLowerFunnels in the lower lips.
Reference ImageLipFunnelFunnels in the upper and lower lips.
Reference ImageLipPuckerUpperUpper lip part pushes outward.
Reference ImageLipPuckerLowerLower lip part pushes outward.
Reference ImageLipPuckerLips push outward.
Reference ImageMouthUpperUpRaises the upper lips.
Reference ImageMouthLowerDownLowers the lower lips.
Reference ImageMouthOpenMouth opens, revealing teeth.
Reference ImageMouthRightMoves mouth right.
Reference ImageMouthLeftMoves mouth left.
Reference ImageMouthSmileRightRight side mouth expresses a smile.
Reference ImageMouthSmileLeftLeft side mouth expresses a smile.
Reference ImageMouthSmileMouth expresses a smile.
Reference ImageMouthSadRightLeft side mouth expresses sadness.
Reference ImageMouthSadLeftRight side mouth expresses sadness.
Reference ImageMouthSadMouth expresses sadness.
Reference ImageMouthStretchMouth stretches.
Reference ImageMouthDimpleLip corner dimples
Reference ImageMouthTightenerMouth tightens.
Reference ImageMouthPressMouth presses together.

1: Unused by all interfaces.

2: Physically 'impossible' from normal anatomy.