Hooking Up the Head Skeletal Hierarchy

For the head of a character, you can create a separate hierarchy that is point-constrained to a locator that is a child of the spine or neck. This leaves the rotational controls free from the hierarchy and enables the animator to animate them by hand (see Figure 17.62). You will do this in the next exercise.

Figure 17.62
IK layout for the head.

Exercise 17.10 Attaching the Head Setup

This is a short exercise that goes through a few simple steps to create a joint hierarchy for the head. The head is created first. Then it is connected to the neck using a combination of constraints that allow for additional freedom when animation occurs, giving the character's head extra flexibility later.

1. Create the head joints for your character using a similar joint layout as shown in Figure 17.62.

   It is a good idea to place the jaw's point of rotation slightly in front of and below the side view of the ear lobe. Usually you should include a few extra joints that stem from the jaw, as well as a joint that goes up to the top of the head of your character, for extra weighting of the facial geometry.

2. Next, create a locator and point-snap it to the root of the head skeleton that you just created. Make this locator a child of the nearest neck joint.

3. Point-constrain the head's root to this new child locator by selecting the locator and then the head's root joint, and performing Constrain, Point (see Figure 17.63).

   This setup allows the character's head to rotate freely from the spine and neck, but it still translates around with the neck and spine appropriately. If you need to translate the neck by any small amount, the ability is there by moving the locator that the head is constrained onto.

   

   Figure 17.63
   Full head setup with control boxes.

Facial Controls and Blend Shape Deformers

Although facial rigging was a smaller portion of the setup for this project, the way that the rigging was accomplished can also be used for complex scenarios of lip-synching and high-range emotional facial animation. All facial expression controls can be successfully implemented in a very traditional way. You first model them as separate models and apply them as blend shapes targets. Then you rig each attribute of your blend shape into a single faceController node simply and quickly by adding attributes. Then you use the Connection Editor to quickly hook them all into the single faceController node so that they are easily accessible to the animator.

Eye blinks can also be modeled as blend shapes and hooked up using set-driven key onto attributes of a driver. Each eye should have a separate blink control so that the eyes can blink at an offset of each other (see Figure 17.64).

Figure 17.64
Blend shape setup for eye blinks.

The opening and closing of the jaw can be achieved using joints and painting the smooth bind weights to achieve an appropriate and appealing opening and closing of the mouth corners.

It is important to note that all the blend shapes for the lips must be modeled with the geometry in the default pose, with the mouth closed, to avoid double transformations of the jaw being double deformed while opening.

Tip - To create blend shapes for a character that has already been bound to a skeleton, you will want to be sure of two things:

Be sure that you are using an exact duplicate of the character's geometry before it was bound to the skeleton to begin modeling your blend shapes.

When you create the blend shape, go into the Advanced tab in the Create Blend Shape options box and choose the Front of Chain options in the deformation order pull-down menu. Or, after you create the blend shape, choose Inputs, All Inputs and use the middle mouse button to drag your blend shape to the bottom of the deformation order list (just above any tweak nodes there—see Figure 17.65).

Figure 17.65
List of history operations window.