So, one must go into pose mode in MPFB and zoom in on the face. By default it will have the bones in neutral positions depicting a blank expression. In MakeHuman's expression selector, it will be labeled "none".
- Face Bones in MPFB/Blender workspace
Look at all those bones. Some are for the cheeks. Others get the eyes and brows. Then there are the lips and jaw. Oh, and then there is the tongue. Holy bejesus, that's a lot of stuff to mess with.
To make things easier, it is prudent to have the helpers engaged when the model is made from scratch. All of them must be on, with weights. This makes things much easier but it is still not a simple task since every one of those bones will affect all the others when moved.
It also helps to have a solid grip on how facial anatomy works. If you have a good mind set and understand what happens as the face moves, you will be able to move those bones around and get at the expression you are after. A word of advice: they are very sensitive. A little goes a long way, so be gentle when making changes.
Chances are, you will need to hit edit undo a lot as you poke and stretch the features of the face. It does not matter if it is a frown or smile, anger or joy, effort or rest. Study photos of faces and pay really close attention to how things move as expressions change. Then practice, practice, practice.
I give some examples below from a series of shots taken during a session with my female_006 model. The hair is by Culturalibre. The expressions were arrived at using the default rig bones operating with helpers and weights with IK support (thanks, Joe).
First, a blank expression. She just stood there with her mind off in space somewhere. Alcohol will do that to a body. She insisted. We served. She drank. She took her clothes off. Yep. Tequila. Straight. With a lime to suck on and salt to lick off her thumb web. Tradition!
- Default Blank Face
Next, a bewildered smile. The drinks are kicking in and not in a good way, but she is trying to hide those feelings with a cheeky grin. Meanwhile down around the belt line, things are beginning to slosh around...
- Bewildered Smile Face
Finally, a classic rolling stone face. The room is spinning a bit and she might have to spit that junk out big. Good thing there is a bucket near by. Musicians and their groupies can make a lot of trash...
- Rolling Stone Face
These expressions each took over fifteen minutes to make. The rolling stone face was the hardest because that tongue is a touchy item and I had to back out and start over a few times. It will twist every which way until one learns how to go slow and easy with the little rigging helper tools.
In all instances, doing this work without the rigging helpers would not be practical due to the time it would take to tweak each individual bone. The little helpers make the bones move in a logical way based on motion vectors.
To use the helpers, you first click on one and then click again as you hold the mouse button down while dragging it. You will also need the viewport panned in the direction of the vector so that its movement is visible and predictable. Once an expression is set, it can be saved as a JSON pose and exported as a BVH pose.
A word about saving poses as JSON files. If you make a mistake and mess up a pose, you cannot overwrite that pose after correction. You must first delete the file and save it again after your changes. Also, the pose files are buried in the file structure within MPFB under data/poses/default-IK/*.json. I go in there so often that I had to bookmark the folder in the file manager.
I am making progress, yes...
