Updating Neck RBF Setup Tool Drivers

The MetaHumans facial (neck) rig has one RBF solver which has three main neck joints as inputs:

• neck_01

• neck_02

• head

It also has 37 predefined poses, which are different rotation combinations of these 3 joints. These poses then trigger 18 corrective expressions with different multipliers. These expressions are joints and blend shape deformations driven through RigLogic, similar to the rest of the facial rig expressions.

The image below is a preview of the facial rig setup:

To edit rotations of these three neck joints, proceed as follows:

1. Load the DNA file you want to edit in the MetaHuman Expression Editor.

2. Select Update Drivers for Neck RBF Setup from the Tools menu in the Expression editor.

   

3. Click Assemble.

   

4. Two groups appear in the scene:

   • The driver_group, which is the default MetaHumans rig which has all 37 poses on the timeline.

   • The driven_group rig from the DNA file.

   

5. Neck joints from the driver_group have default animation for every RBF pose on the timeline:

   

   Neck joints from the driven_group (from the DNA file) are static, and waiting to get animation.

6. To have the neck joints from driven_group match the animation for joints from driver_group, use the orient constraint functionality in Maya.

   • Go to Frame 0 (neutral).

   • Constrain the joints neck_01, neck_02, and head from driven_group to their corresponding joints from driver_group.

   • To change input rotations for any joint in any RBF pose:

     • Add a new animation layer for joints in driven_group.

     • Go to the pose (frame) you want and adjust the rotations there:

     

   • When you are done, click Save. All the input rotations for all RBF poses from the timeline are saved to the specified DNA file.