modelling Facial Shapes Info
FACIAL SHAPE MODELING
The face is driven by muscles which act like pulley systems, contracting and relaxing to move the surface of the face around.
As animators the more realistic we venture the more we have to stay true to how the face actually works with all of it’s muscles. Since Gollum, Weta Digital individually sculpt each muscles effect on the face like described in the Facial Action Coding System by Paul Ekman, then they have to remodel all the corrective combinations. It’s a laborious job and can take teams of modelers years to create a large movie like Avatar. Few companies, even the big ones use proper muscle sims for the face.
There’s plenty of cheats we can use along the way that can give good fast results. Often simple solutions can give us a lot of freedom. Sculpting and soft select tools are making the creating of facial shapes much easier than they used to be. Blend shapes can be sculpted as one shape and then broken down into eye/mouth/left/right combinations later very easily.
Always use reference, use a mirror or webcam, find images closest to your style on the internet.
Pinterest is a great starting point…
FACIAL JOINTS/CLUSTERS VERSES BLENDSHAPES
The jaw is a big hinge which pivots from below and in front of the ear. It can both rotate and translate. The bottom teeth are attached to it and the top teeth don’t move they are constrained to the skull. We can cheat the teeth for stylisation purposes but it’s better to keep this to a minimum unless the style calls for it.
I prefer to use the 3 joint jaw setup. It allows for extra freedom for the lips to move independently to the jaw and gives the animator some extra control, it’s not realistically how the face works but it gives us an extra layer which is very handy for expressiveness.
The jaw can be animated with blendshapes, but this is tricky and can look swimmy, much better to skin up the jaw in most circumstances.
Highly cartoony characters are the exception and can break many of the rules of the facial setups.
THE MAIN FACIAL BLENDSHAPES
Blendshapes are a great time effective solution which doesn’t over complicate the controls of the face. It’s a fast system that can animate in realtime. We can sculpt the face exactly as we want custom senarios or designs might require custom blendshapes.
Almost all expressions should be separated for left and right for asymmetry.
There’s a good web application page here that describe the muscles and how the face works.
Innerbrow Up Down (L R)
Midbrow Up Down (L R)
Outer Brow Up Down (L R)
Brow Cruncher (for fear and anger) (L R)
Eyes Open/Close (often made with joints) (L R)
Eye Movement shapes (often made with joints) (L R)
Happy Eyes (crows feet bottom lid up) (L R)
Squint (L R)
Cheek Raiser (L R)
Sneer (L R)
Puff (L R)
Suck In (L R)
Smile (outer edges pulled up and out, often moves lips up) (L R)
Frown (outer edges down, extreme can fire neck) (L R)
Sneer Upper Lip (like sneer)(L R)
Grrr (Lower Lip Grimmace, fires neck muscles) (L R)
Pout (closed mouth pushing top lip)(L R)
Pout Bottom Lip only (optional) (L R)
Kiss (lips tighten push out)
Lips in (edges together)
Lips out (edges out)
Top Lip Roll In (suck)
Bottom Lip Roll In (suck)
Top Lip Roll Out
Bottom Lip Roll Out
Ooohh shape (like kiss but for phonemes, jaw slightly open)
Ffff (bottom Lip tucks under teeth for F shape, jaw slightly open)
PHONEME LIP SHAPES
Phomemes are mouth shapes that generally match up to lip sync. If the face has been setup correctly then many of the phoneme shapes should mirror the lip shapes, in many cases it is not necessary to have phonemes at all. In other cases with more stylised characters there may be specific shapes for the phonemes and they can be modelled custom as the style dictates.
Phoneme Blendshapes can also be modeled with the jaw slightly open, as it would be in real life.
And now of course with cartoon characters we can take our phonemes pretty far, as seen in Ren And Stimpy…
FACIAL ACTION CODING SHAPES
These are the shapes from FACS that might be applicable to morph targets/joints.
Original Paper can be found here
More detailed information with pictures can be found here too…
1: Inner Brow Raiser (Frontalis, Pars Medialis)
2: Outer Brow Raiser (Frontalis, Pars Lateralis)
4: Brow Lowerer (Depressor Glabellae; Depressor Supercilli; Corrugator)
5: Upper Lid Raiser (Levator Palpebrae Superioris)
6: Cheek Raiser (Orbicularis Oculi, Pars Orbitalis)
7: Lid Tightener (Orbicularis Oculi, Pars Palebralis)
8: Lips Toward Each Other (Orbicularis Oris)
9: Nose Wrinkler (Levator Labii Superioris, Alaeque Nasi)
10: Upper Lip Raiser (Levator Labii Superioris, Caput Infraorbitalis)
11: Nasolabial Furrow Deepener (Zygomatic Minor)
12: Lip Corner Puller (Zygomatic Major)
13: Cheek Puffer (Caninus)
14: Dimpler (Buccinnator)
15: Lip Corner Depressor (Triangularis)
16: Lower Lip Depressor (Depressor Labii)
17: Chin Raiser (Mentalis)
18: Lip Puckerer (Incisivii Labii Superioris; Incisivii Labii Inferioris)
20: Lip Stretcher (Risorius)
22: Lip Funneler (Orbicularis Oris)
23: Lip Tightner (Orbicularis Oris)
24: Lip Pressor (Orbicularis Oris)
25: Lips Part (Depressor Labii, or Relaxation of Mentalis or Orbicularis Oris)
26: Jaw Drop (Masetter; Temporal and Internal Pterygoid Relaxed)
27: Mouth Stretch (Pterygoids; Digastric)
28: Lip Suck (Orbicularis Oris)
38: Nostril Dilator (Nasalis, Pars Alaris)
39: Nostril Compressor (Nasalis, Pars Transversa and Depressor Septi Nasi)
41: Lid Droop (Relaxation of Levator Palpebrae Superioris)
42: Slit (Orbicularis Oculi)
43: Eyes Closed (Relaxation of Levator Palpebrae Superioris)
44: Squint (Orbicularis Oculi, Pars Palpebralis)
45: Blink (Relaxation of Levator Palpebrae and Contraction of Orbicularis Oculi, Pars Palpebralis)
46: Wink (Orbicularis Oculi)
Below are some character facial model sheets. Always look at ref, weather it real life or how other animators have achieved emotion in the face. Again Reference Reference Reference! We may think we know how the face works but by really studying good reference we’ll find the details that can really elevate our work.
There’s loads of facial reference guides around on the net, Pinterest is a great place to spot collections for facial reference like this one…
1.1 – Nicole Kidman
1.2 – Lie detection-Prof.Paul Eckman
1.3 – LIE TO ME FACES PROMO
1.4 – Dr.Strangelove-Precious Bodily Fluids
1.5 – Muscle Based Face Rig test
1.6 – A Grand Day Out:Building A Rocket
1.7 – Tough Guy Topo Facial Test
1.8 – Eye Closeup with Kodak Zi6
1.9 – Animation Scout-Eyelids
1.10 – Character Animation and Facial Expression Tips by Tania Simeons
1.11 – Markerless Facial Motion Capture Demo
1.12 – Then…Suddenly
1.13 – Masterchef:The Professionals-Matt makes a facial expression like a Pixar animation
EMOTIONS OF THE FACE
Facial Recognition as Hardwired
Faces are hard wired into our brains they are paramount to our survival. Paul Eckman was one of the first scientist to prove that facial expressions are universal and not learned. He did this by trekking into the remote areas of Papua New Guinea filming the people who had never had outside contact before.
Facial expressions can be very subtle.
A leading scientist in the research into faces Paul Eckman
Paul has become famous through television as seen in the show Lie To Me where Tim Roth Plays Paul Eckman. Pauls books are very interesting and whilst they’re not exactly made for animators there’s a bunch of interesting insights into how the face works.
Here is another promo with an educational bent…
Weta have used the Pauls FACS (Facial Action Coding System) as an integral part of their facial rigging since Gollum on Lord of The Rings. On Avatar for example all the sliders on the face correspond to facial muscles not phonemes (word sounds). This is great for realistic characters which must behave well, realistically. For more cartoony characters we can get away with a lot more simplicity and phonemes are still a large part of a facial library. There’ are many different types of rigging when it comes to faces and many different styles. A good rig will give the animator a wide variety of shapes to work with.
The difficulty of facial animation comes from the fact that every person is a facial expressions expert, but unlike Paul Eckman it’s mostly from unconscious knowledge, we can often tell when something is off but we won’t know why!
The Facial Expressions
Facial Expressions are pretty well known. But the details of how the face works is actually pretty amazing. A great book for facial expressions is The Artists Guide to Facial Expressions by Gary Faigin. For serious animators it’s worth reading from cover to cover and explains the way the face works very clearly.
The face is driven by muscles which can only pull. One end of the muscle is attached to bone and the other end is connected to the skin, that’s how the mechanics of the face work. here’s a rather ammeter facial rig driven by muscles, although rather primitive it does give us a good rough idea of how the face works…
Keeping Facial Simple
Faces needn’t be complicated. Here is a great example of Grommit, from Wallace and Grommit, who communicates very clearly not by talking but by subtle adjustments to his eye brows.
The Facial Expressions of the Iron Giant are worth a study in simplicity too. Such a wonderful design for a character with remarkably few moving parts and yet so much expression!
Animating Facial Expressions
While animating facial expressions we can assume a few things.
1. Facial expressions can be very fast, much faster than other parts of the bodies. It is very hard for a facial expression to float over more than 10 – 15 frames try it yourself.
2. Parts of the face move very fast and individual parts move at different speeds and can have slight offsets.
– Eyes are very quick, to the point that eye darts can be over one frame. Eyes will rarely move over more than 4 or 5 frames. They are very quick and often keep to 2-3 frames as a good rule. The muscles of the face are also very quick and are the first to react to thought.
– Brows can be a little slower than the eyes and lag a few frames but they are still very quick and usually animate them over less than 10 frames.
– Mouth can lag a little more from the brows but are still very quick and should be under 10 frame transitions.
4. Eyes lock onto objects and stay aimed at them, they don’t move with the face. This doesn’t necessarily mean keep them on aim constraints but just keep that in mind.
5. Watch the iris/pupil placement, realistic characters will rarely show white above the pupil except in shock or horror. Cartoony characters this is more about ratios of white. Covering this iris will make characters look sleepy.
6. Eye movement/direction can change the shape of the surrounding lids. Animate the lids with the eyes unless automated.
7. Eyes and brows are most important for facial expressions, without the mouth expressions can be clear.
8. Be sure to add arcs and in-betweens in poses, faces rarely have linear transitions, usually they compress or extend on the inbetween, especially in the case of blinks.
9. Blinks can be very quick, almost to the subframe level. Slow blinks like in love scenes usually represent a very dramatic moment. Keep them fast!
10. The face is extremely versatile even in real life, it can be pushed in large variations, the face also has a habbit of maintaining volume, so add squash and stretch.
11. The Jaw is a pivoting bone but it can also move slightly, the lower teeth are welded to it and the upper teeth don’t move as they are welded to the skull. But on stylised characters the teeth can be moved independently from the jaw and skull, though do so sparingly and hiding the transitions with closed mouths. Teeth shouldn’t float around the face, they placement on the teeth in relation to the mouth can signify a lot of different expressions.
12. Don’t forget asymmetry, facial expressions are rarely symmetrical. Counter posture usually works for the brows and mouth, opposites up and down.
Animation Scout has some great short little videos on facial tips…
Other Facial Animation Tips from Animation Mentor
For more go to their vimeo page.
Finally here’s some interesting videos, example of facial capture. Couple of things to watch is the movements of the face because it’s much easier to break them down while watching the fake character. Also you can see how much subtlety is in realistic facial that gets lost. On movies like Avatar the facial mocap artists take great care to animate the face whilst looking closely at the ref provided by the facial cams. Animators will further tweak the animation too, it doesn’t just come out of the box looking all peachy!
For our own purposes it’s important to stylise and caricature our facial when it comes to animation.
And one more this time check out he expression at the end
Great photos of kids crying here