FBIK joint labelling and naming methods

There are three methods you can use to rename your joints so that they follow the FBIK joint labelling and naming conventions:

Joint labelling
Renaming your character’s joints
Specifying custom joint names with MEL.
NoteIf you label or rename only the base joints in your character’s skeleton, the joints in between the base joints will not be controlled by full body IK. If you label or rename all your character’s joints, then the hikSolver will produce better results as its solution will include all your character’s joints rather than just the base joints.

Joint labelling

You can use joint labels to tag your character’s joints so that when you create your FBIK effectors, all the labeled joints are included in the full body IK solution. When using the labelling FBIK joint labelling and naming method, you can label only your character’s base joints, or you can label all your character’s base, roll, and many of the auxiliary joints.

Joint labelling produces a complete full body IK solution. However, joint labels do not exist for the specialized InHand, InFoot, or HipsTranslation auxiliary joints. If you want to use these auxiliary joints in your skeleton, you need to use joint naming or MEL instead of labelling. See Accessory or additional joints.

Note

If you label FingerBase or ToeBase joints, their labels will appear as Finger and Toe in the scene view.
For non-grasping hands/feet where their thumbs/big toes move with the rest of their digits (such as quadruped paws and hooves or human feet), name their thumb and big toe joints as ExtraFingers so that the FingerBaseEff and ToeBaseEff effectors affect the digits of the hands/feet.

For grasping hands/feet where their thumbs/big toes flex independent of the rest of their digits (such as human hands or primate hands and feet), name their thumb and big toe joints as HandThumbs and FootThumbs respectively so that the HandEff (wrist) and FootEff (ankle) effectors affect the digits of the hands/feet—rather than the BaseEff effectors.

Joint labels are useful when you do not want to rename the joints in your character’s skeleton. For example, you can use joint labels if you have an existing character with custom joint names or if you are using referenced animation with namespaces.

For most characters, we recommend that you use joint labelling since it is the easiest and fastest FBIK joint labelling and naming method.

Labelling your joints for FBIK is similar to labelling your joints for animation retargeting. For steps on how to label your joints, see Label a skeleton’s joints.

Tip

If you do not see your joint labels in the scene view, select Skeleton > Joint Labelling > Show All Labels.
Label roll joints the same as their parents are labelled. For example, you should label a left forearm roll joint as Elbow(L) since the forearm roll joints’ parent joint is labelled Elbow(L). Roll joints are supported for the elbow, shoulder, hip and knee.
You can automatically label entire limbs at a time, rather than labelling each individual joint in your character’s skeleton. See Label a skeleton’s joints.

Renaming your character’s joints

As an alternative to joint labelling, you can rename your character’s joints to produce a complete full body IK solution.

When using the renaming FBIK joint labelling and naming method, you can rename only your character’s base joints or you can rename all your character’s base, roll, and auxiliary joints. See FBIK joint types.

For FBIK to work on your character, you are required to at least rename your character’s base joints according to the FBIK joint labelling and naming conventions. See Base joints. Renaming only your character’s base joints is useful for simple biped characters that do not have any custom or specialized joints, but require the ability of basic feet flexion. This joint naming method produces the simplest full body IK solution because the FBIK effectors that are created with this naming method will only use the main joints and not the rest of the joints in your character’s skeleton (for example, roll joints or finger and toe joints).

If you want to include all your character’s joints in your FBIK solution—including auxiliary joints like the InHand/InFoot or ToeBase/FingerBase joints, then you should rename all the joints in your character’s skeleton.

Specify custom joint names with MEL

You can create a custom joint naming convention for your full body IK using MEL to meet the special needs of your production or game pipeline.

The -sourceSkeleton (-sk) flag on the characterize command lets you specify the association between your character’s current joint names and the FBIK joint names that adhere to the FBIK joint labelling and naming conventions. For each joint you want to include in the FBIK solution, you need to specify a partial path for the joint and the name of the full body joint it represents. These must then be separated by spaces, and multiple entries need to be separated by commas (,). For example:

characterize -sk "myhips hips,rightHip rightupleg,leftHip leftupleg,..."

This MEL string tells the characterize command to look for and use the alternate joint names (provided within the quotation marks of the string) during the full body IK solution.

NoteWhen using MEL to specify custom joints names for FBIK, you cannot have multiple joints in the scene with the same name. Instead, you need to provide the partial path name for the joints that are named the same.