Here's a list of facial morph/blendshape targets that I'll be using for my character, with explanations (for 3D dudes, not for the common folks... :D ), sort of like a... tutorial. But only 'like' :D ...
[Up, Low, Left, and Right = these show that I'm using separate shapes; for example, AU25 Up and Low/Left and Right means that I want to be able to part the lips as follows: Left Upper Lip Parting, Left Lower Lip Parting, Right Upper Lip Parting, Right Lower Lip Parting].
[I'll keep refering to morphs & blendshapes, but they're the same thing, just wanted to mention, so there is no confusion].
[I also use Paul Ekman's allmighty FACS AUs = action units, as a guide, so you can refer to more information in the FACS. In fact, you should refer to or have some knowledge of the FACS if you really want to understand all the blah blah blah. Some AUs I don't even describe or talk about, because they're basic :D ].
[I'll also be refering to BCS and combination sculpting or corrective shapes, for more detail on this check out Daniel Pook-Kolb's website].
And here the list starts:
BROWS
AU1 Inner Brow Raise - Left and Right
AU2 Outer Brow Raise - Left and Right
AU4 Brow Join + Lower
+ Forehead Clench (this I couldn't find in the FACS but is useful - it covers most of the skin around the skull actually, not only the forehead and temporal bone, but also has a slight effect on the back of the head too; not sure what muscles are at work... it's a stretch of the skin on the head - mostly forehead and temporal area - pulling the skin back, towards the ears, and up. this action is used often in fear or amazement, along with the wider opening of the eyes. it's action is subtle though)
LIDS
AU43 Eye Close + AU5 Upper Lid Raise - Left and Right (eye lids closing should go as far as lids pressing against each other. this is basically one action as far as I'm concercened, and even Ekman sais something about AU43 and AU5 as being basically one unit, I think. so at one end the upper lid is maximum wide open, then it closes gradually, and at the other end it shuts, and THEN it presses against the lower lid - this never happens in a blink, but when you close your eyes you can see the difference from barely touching closed lids and really closed lids that press against each other)
AU6 Cheek Raise - Left and Right
AU7 Lid Tight - Left and Right
+ Fleshy Eyes (I'm building fleshy eyes with a set of morphs (+ inbetweens, ideally, but I guess it might work without... too...), as follows: eye up is accompanied by an eye-up-flesh-movement all around the eye, eye down another flesh movement, eye left same, eye right same. The flesh movement is basically nothing but a ripple pattern: you displace the skin around the pupil of the eye and move that displacement like a ripple moves on water. the ripple/displacement also stretches the skin around in a subtle manner, you can feel that by placing a finger beneath one eye and looking up. for detailed explanations on how to setup fleshy eyes check out Hyper-Realistic Facial Setup from Gnomon - they don't do it with morphs, but you'll get the ideea) Here's an image:
[I'm disregarding the wink since I prefer to build it as an eye closure plus cheek raise]
NOSE
AU9 Nose Wrinkle
AU38 Nostril Dilate
AU39 Nostril Compress (big problem with AU38 and AU39, I guess, since almost all upper lid movements affect the tip of the nose, which means this is an area that needs tons of corrections in a combination-sculpting workflow, a-la-Bay Raitt - Daniel Pook-Kolb. In a normal workflow... the area probably needs to stay mostly rigid, which sucks :| ).
MOUTH
AU10 Upper Lip Raise - Left and Right (basically, pushing the lip up, vertically, into a square shape. now this is actually a sneer and can't be used instead of lips parting, for anything pleasant, such as in a smile... it's a nasty shape we don't use very often).
AU12 Lip Corner Pull horizontal - Left and Right (I'm not using this for smile actually, and I'm not sure if it's right, but I'm sharing it with you anyway: I use AU12 for an EEE shape, and add AU13 if I need a smile; also AU13 can be used alone, without widening the mouth. I also use it for an extra widening of the mouth in AU15).
AU13 Sharp Lip Pull vertical, in smile - Left and Right (as I said above, I use this in conjunction with AU12 if I need a wide smile).
AU14 Dimpler - Left and Right (a way of tensioning the corners of the mouth, not used in smile or just as a crease... you use it in an "ok, whateeeeveeeeeeeer..." - type of face, in an facial expression suggesting annoyance or disbelief. sort of a straight face, like this :| but narrow!).
AU15 Lip Corner Depress - Left and Right AU16 Lower Lip Depress - Left and Right (same as with AU10, this action can't be used instead of lips parting, it's sort of an opposite of sneer... it can be used in disgust, pain, etc.).
AU17 Chin Raise (I don't push the upper lip with this one, better have more flexibility. like if you want to roll the upper lip IN and do AU17 - the upper lip won't be affected by AU17).
AU18 Lips Pucker - Left and Right (no rolling here, just some protruding forward of the lips, the OUT rolling comes separate in AU22).
AU23 Lips Tight
AU24 Lips Press (this is for example an action where I use inbetweens just to enrich the deformation, not for rotating).
AU22 Lips Funnel/Roll Out - Up and Low
[might split it into Left and Right too, just for fun, although I'm not sure if that's possible in reality, but anyway, flexibility is the name of the game!!!] (this is a based on pure rotation, with falloff on the margins, of course, and you definitely can't rotate lips in a linear fashion, you need inbetweens - I, with BCS, need only 1, because the soft gives me a free arc, but normally, if I had to do it in Maya, I'd need at least 3, 4 inbetweens, to get rid of the nasty linearity ;) you might need to add some protruding forward on the lower lip, maybe on the upper too... but definitely be subtle about that translation/protruding - most of this action is rotation. In the Gnomon DVD I mentioned earlier you have a really, really ugly/unsuccessful example of a Low Lip Roll Out. It was done in a haste and it looks wrong. I think this is an especially sensitive and difficult-to-build AU, especially on the lower lip - hi hi, and people who think they can have it for free with joint/clusters rotations, they're wrong... it's not just rotation, it's a juicy complex deformation).
AU28 Lips Suck/Roll In - Up and Low (same as above, you've got rotation here, but this time make a nice stretch into the mouth. actually, this is a more intricate deformation, with rotation + stretch, but easier to build, I guess, because you can't see the details inside the mouth).
AU25 Lips Parting & AU8 Lips towards each other - Up and Low/Left and Right (smoothly raise and lower each lip with no or very little action/falloff over the corners of the mouth. This AU had my head twisting and boiling and... oh, man, it was a nightmare until I realized this is actually the action I need. Hm, I'm not even 100% sure yet, more like... 70-80% :) The idea is that you need to open the lips without opening the jaws, in a smile for example, but not only. How do you do it??? With AU10 and AU16??? No way! Read my comments under AU10 and AU16. It's actually the lips parting that do the job, and it's probably a function of the orbicularis oris, but I didn't check. This muscle is the real nightmare of facial setup, oh, man, I swear it is!!! Anyway, lips parting: I'll create an opposite 'lips uniting' too, probably Ekman's AU8. Even though in a closed mouth AU8 would actually create interpenetrations, it's a necessary shape, unless you replace it with AU27.X, but I'm not sure if it works - AU27.X is invented by me. Read about it below.).
AU27 Mouth Stretch (normal mouth stretch, with the lips opening along with the jaws).
AU27.X Mouth Stretch without opening lips! (Now here's a juicy one: it's not nice to chew with your mouth opened, but hey, you actually DO open your jaws to chew! you also open your jaws without parting/opening the lips in an "oh, really??? don't say..." - type of expression, again, in disbelief. or in many other cases, when you 'face is falling'. or in surprise. this can be done with AU8, maybe, but I'm not sure how well it would work in a morph, because you have to be able to close the lips tight & perfect. So instead of counteranimating a 'lips unite', I prefer to build these 2 shapes, AU27 and AU27.X separately, and then have a corrective shape for the 2 of them that, when both are used, only one is active - in other words, when AU27 and AU27.X meet, only AU27.X will be used, for example, and then slowly fade out from AU27.X and you're left with a normal open mouth. This is possible with combination sculpting. Which is a problem, of course, because you ultimately need a software, like BCS, within your 3D application, to allow for combinations/corrective morphs... so it doesn't work in a normal morphs workflow).
+ Sticky Lips (One idea I'm having here, but didn't tested it yet, again, based on combination sculpting and it doesn't work in a normal morphs environment: you build one open mouth with Sticky Lips and one without. The one without SL would override the one with SL, so you can turn the feature off, like you'd need to do each time you close the mouth - you only need the SL to be active when you open the mouth, normally. But then you can fade in and out of the corrective shape - the one without SL - to your heart's desire, and get more or less stickiness. Now, how do you actually build the open mouth with SL: simple!!! A bunch of inbetweens - well, not necessarilly a large bunch, maybe 2 or 3 might do the work, I don't know, but it sure would look better with a bunch :) now, what you need to do is animate the stickiness itself through a chain of inbetweens - you delay the middle of the lips in an overlapping manner. the nice part is that you get to sculpt the stickiness, which is a creative process, and you get full controll over the looks of the stickiness; to get really, really hardcore, you could even model more than 1 stickiness, and create a couple different ways to un-stick the lips, and the animator simply choses between them: like "this time I'm using SL3... next time SL1..." the timing on the stickiness would be entirely the animator's job, which is flexible, which is good ;)).
[I'm disregarding AU26-Jaw Drop because I make it part of AU27-Mouth Stretch]
[I also didn't add the very important Mouth Rotate Left and Right (as a cool thing... one might add Rotate Up and Down too, although it's not found in humans, the pseudo-rotation Up & Down is actually a combination of other AUs, involving lip rolling and lip parting, I think, but I don't know for sure). The left-right action is also not really a rotation per se, all in all, but a combination of rotating and translating. I guess it's an orbicularis oris action, he must have did it again (give me nightmares)! I do all this with a face cluster, but in a trully realistic model I'd have to be more accurate and create morphs. In a cartoony character, the cluster, affecting mostly the lips, but with a carefully painted falloff all over the face, does miracles :) One cluster only!]
AU29 Jaw Thrust
AU30 Jaw Sideways - Left and Right
AU31 Jaw Clench (well, with action visible in the cheeks, towards the base of the jaw).
+ Jaw Twist (If I'd want to get fancy, like they do on the aforementioned Gnomon DVD, I could also add unnatural jaw rotation around the depth axis. They do it with joints, but it can also be done with morphs, why not? :)).
AU34 Puff - Up, Low, Left and Right (This is not only a cheek puffing as found in Ekman. I need each cheek to fill with air/puff independently, which is what Left and Right means, but we also need the upper and lower mouth to puff; one can fill these spaces with air too: above the upper lip and below the lower lip).
AU35 Suck - Up, Low, Left and Right (The opposite of Puffing. Sucking your upper lip is especially subtle - this is absolutely not the same as rolling it IN!! - , the rest of the 3 are not subtle).
[And I'm disregarding AU11 (AU11 might actually help somewhere... even though in Ekman's example is really subtle, I guess you can make it more prominent, more obvious. not sure how useful it is, but then, that doesn't mean it isn't, it's just that I couldn't find its purpose YET!)]
NECK
U21 Neck Tight
And that's it.
All these shapes should create a pretty complex facial setup... of course, the real deal is in how they work together. It'll be tough to follow the signature wrinkles, how they soften or deepen, appear and dissapear with each facial action (Gary Faigin's "The Artist's Complete Guide to Facial Expression" is a really nice material on this, it follows the signature wrinkles actions as they evolve from a facial shape to another). And, also, as I said, before, adding inbetweens to create richer deformations... that's another 'real deal'.
The skin needs to be affected, around each AU, with a falloff, ideally, but then this is only possible in a combination system like BCS. There should be possibilities for combinations/corrections of morphs in every 3D package, but unfortunately... there aren't, as far as I know, in any :( There can be no high-quality facial setup with morphs alone, without a way of correcting them, that's frustrating. Gollum is the living proof that high-quality faces CAN be done with morphs alone, but you need a combination system, like the one used by Weta or like BCS.
Now, as a conclusion... don't trust anything I say, check first, I'm not a face-expert, not by far, and the face is anyway quite a mistery to science yet (duuudes, this is so crazy, we're in the 21st century by God!)... so verifying from n sources is maybe our only chance to get to some decent conclusions... Anyway, please correct my mistakes dudes, if you have time, let me know what you think about my above description of AUs and stuff, and please let me know if I'm off with things. Thanks. Ciao!