Facial Rig

Introduction

Facial rigs are a way to give your character’s face more life. There are multiple ways to design a facial rig, from blend shapes to CV curves. I decided upon a joint structure facial rig, as joints are something I am accustomed to and have worked with before, so I know how they function.

Pre-rig

We will start by doing the same process as with any joint rig: creating clusters. Clusters, as stated before, are used as guidelines for our joints. For a facial rig, I will not be turning my model to wireframe only, for all the joints will be on the front of the face.

                

To begin, We will start with the bottom lip of the mouth. We will create a cluster in the middle of the lip, one on the far right side of the lip, and one in between the middle and far clusters. Repeat this process for the upper lip.

Next, we will create clusters for the cheek. The difficulty of this process can range from easy to hard, depending on your model. If your model has a good cheek definition, then this process will be fairly simple. For my model, the cheek line starts slightly right and above the end of the nose and makes an arc down to the mouth. You should place a cluster at each vertex along that path. My model gave me between 5 and 6 clusters on that path.

For the eyes, we create one for the bottom and one for the upper eyelid. We will then do the same process with the cheek line with the eyebrow line, a cluster at each vertex the eyebrow should be. I had, between 5 and 6 clusters again.

The pre-rig work is now complete.

Joints

We will now switch our model off, make sure our file tabs are set to “Animation,” and go to Skeleton > Joint Tool to start creating our bones.

We will start with the cheek clusters this time, as they are the only joint chain (initially) in the face rig. Starting from the top, hold down “v” and snap joints to the clusters.

We will do the same for the outer clusters of the lips, starting with the half way cluster and moving to the far cluster. This should produce one bone for the upper lip and one bone for the bottom lip.

For the next set of joints, we want all of them to be separate except two. Starting with the lower eyelid: hold “v,” create joint, press “Enter,” and then press “g” (“g” will give you the last tool you used, and in our case that is the joint). Repeat this process for the entire eyebrow and center of both upper and lower lips.

One half of your rig should be complete.

We will now mirror all the joints, except for the two center lip joints. To do this, go to Skeleton > Mirror Joints > Options Box. In the options box, make sure you are mirror across the right planes.

You should now have a full face rig. Before we move on, we will also attach the four outer lip joint chains to the center joints of the lips.

Handles/Constraints

For the handles, I decided to use something different than the normal CV Circles. I will be using poly spheres to visually represent my face.

Begin by creating a sphere by going to Create > Polygon Primitives > Sphere. We want the sphere to be a little bit bigger than the size of our joints. We will be creating a sphere at every joint, so we use the same process as with the clusters and the joints by holding down “v” and snapping the spheres to the joints.

I suggest moving your facial rig a little distance in front of your model so that you will be able to see the changes without the interference of the handles. We will now freeze all the spheres by going to Modify > Freeze Transformations. Like in the basic rig, freeze transformations will make it easier to revert back to the neutral pose.

We will now Parent Constrain all the joints to their respective spheres. Select the sphere and then the joint and go to Constrain > Parent > Options Box. In the options box, make sure maintain offset is selected and click “Apply.” You should now be able to translate and rotate your rig through the spheres.

Weight Painting

Weight painting for a facial rig can become very tedious when trying to get the perfect facial constructions.

To start with, we will bring up the paint weights tool by right-clicking our model and selecting “Paint Skin Weights Tool.” This should turn our model black (representing no influence) and white in certain areas (representing influence). In the paint weights menu, set value to 0, select each face joint separately, and click “Flood.” This will drain all the influence from the face rig and allow us to create our own influences.

For most of the joints, influence will be centered on the joint area. We do not want the face rig to influence a lot of our body.

The exception is the center joint on the bottom lip and the two far outside joints of the upper lip.

For the center joint on the bottom lip, we will set the value back to 1, and paint the entire lower jaw white. This joint will allow our character to speak, so we need the bottom to jaw to move.

For the outside joints on the upper lip, we want our character to be able to smile or grin. We will a good portion of the respective sides, as well as some of the lower jaw.

Our face rig is now complete.