Protected Muscles

The default muscle set of a character is open-ended. You may add or remove muscles and edit them as much as you wish. However, a subset of the default muscles are protected. Protected muscles cannot be deleted in SGX Studio, and editability is restricted. Generally speaking, protected muscles:

are expected to exist by our algorithms;
require a higher degree of precision and understanding of our animation system than typical muscles do; and
on account of that precision, may involve defining multiple poses of the muscle rather than just one.

For these reasons protected muscles are normally set up by trained technical artists and animation linguists on the Speech Graphics team, as part of our character setup services.

Protected muscles include the speech muscles and certain eye muscles. These are discussed below.

Speech muscles

There are 16 muscles that are used in speech animation, all of which are protected. In terms of anatomical regions, these muscles span the jaw, lips, tongue and nose. The speech muscle set has been derived scientifically based on decomposition of articulatory movement into its components. Setting up these muscles involves a number of key poses essential for optimal lip sync quality. The speech muscles are depicted and described below.

Jaw
Jaw Opening
Lips
Adduction
Compression	The lips are pursed without protrusion. The lower lip is more active than the upper lip, and is slightly bowed in the middle, forming a dip. There is dimpling at the sides of the mouth.
Lip Flare
Lower Lip Pull
Lower Lip Push
Lower Lip Tuck
Pinching
Retraction
Rounding
Upper Lip Pull
Nose
Nostril Flare	Both nostrils dilate. There is no movement except in the outer nostril walls.
Tongue
Tongue Advance
Tongue Body Raise
Tongue Retraction
Tongue Tip Raise

For some educational applications, we extend the core muscle set to organs that are not normally visible, such as the velum or soft palate. An example of this is shown below.

Protected eye muscles

The following muscles of the eyeballs and eyelids are protected. These muscles are expected to exist for certain algorithms to function, including the system’s safeguards against eyelid intersections.

Eyeballs
Microdart	The eyeball rolls left (and right) slightly, as when looking between the eyes of a collocutor. This muscle is bi-directional.
Eyelids
Blink	The upper and lower eyelids make contact. Most of the movement is by the upper eyelid. The lower eyelid tenses upward and inwardly.
Eye Close	The upper and lower eyelids make contact. This may be the same pose as blink.
Eye Flare L/R	Widening of the eye, primarily by upward movement of the upper lid. Separated into left and right.
Eye Squeeze L/R	Narrowing of the eye with peripheral squeezing. Separated into left and right. Separated into left and right.
Eye Squint L/R	Narrowing of the eye through the tensing of the upper and lower eyelids. Separated into left and right.
Lower Eyelid Flex L/R	Flexing upward of the lower eyelid. Separated into left and right.

Breath muscles

The Torso section contains one muscle involved in animating the breath cycle.

Torso
Chest Breath