Tips and tricks for making the 52 ARKit shapekeys for facial mocap
General tips on humanoids:
1. Back up your files!! Duplicate your current save at least once per day/two-three hours of progress. That way, if you mess up really badly, you have something to go back to.
2. DONT edit the BASIS shape key! its ur og model!!!if you notice sth wrong with ur base model you can edit it BUT backup before doing so and if ur model is mostly symmetrical (the face at least) unhide all facial components and edit with x-axis symmetry.
3. While making shape keys, such as eyewideleft/eyewideright or anything that has left-right doubles, you can hide all the components from the other side of the face, so you don't accidentally move anything on the other side. mesh symmetry(mirror) wont work on hidden mesh. Related to pt 2, if you go back to editing the base mesh after having done some edits pls make sure to unhide meshes from both sides, turn on mirror, and then edit. VERY IMPORTANT. if u mess up, u CAN fix the asymmetry. but will lose some progress
4. on actually fixing stuff if u mess up. Say you edited sth based on the left eyelid, but you forgot to mirror it to the right side. You can delete the right one and symmetrise the left one over using mesh-symmetry (also i think it can only do left-right) !!for Frame of reference, left-right refers to the left from the model's pov, which is opposite when ur actually facing the character. So work on the left side and copy over to the right is generally better than doing right first and then copying over to left!! If you have existing eye blendshapes, symmetrizing left to right will also cause left blendshapes to control part of the right eyelash. Instead, delete the left shapekeys until all remaining shape keys that influence the left eye are also symmetrical (eg, cheekpuff) then mirror the left eye over to the right eye, and if you fortunately mess up only part of the eye (such as the iris only, eyelash only, or sth) edit the now fixed eye so that it matches the existing correct parts. mirror the right eye shape key to the left and ur good
Anime-style specific tips:
1. Make special shapekeys first (alternate expressions, accessories, etc)
2. To prevent glitching on eyelids, avoid affecting the eye socket on cheek/face shapekeys so the closed eye shape doesn't glitch. you can also do the same for look up-look down shape keys so that the closed eye shape doesn't glitch(you probably dont have to go this far but i have an expression that hides all facial features and exposing the full blank face)
3. You don't have to place the brow/eyelash/highlights pixel-perfect on top of the face, because the structure of the face is gonna cause tons of clipping when it moves, something like up and left at the same time. make them a little distance from the face is perfectly fine OwO
4. Using proportional editing as much as you possibly can. It smooths out the offsets of each blendshape really well, so mix&match shapekeys actually gets pretty results instead of jagged edges. For mouth deforms use vertex-smooth vertices to get smoother results