Fixing the arm twist bones when you first import an animation

From Blue Mars Developer Guidebook

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If you import an animation from Max or Maya back to MotionBuilder, you may notice some weird things happening to the arms.

This is because of the way the arm's twist bones are parented to the arm joints.

This hierarchy will work in Max and Maya, but needs to be reparented in MotionBuilder. Luckily, it is very easy to fix.

1) First, you must be at the first frame of the animation. Select the first bone of the twist hierarchy for each limb:

2) Then, right click on any of the highlighted nodes, select "unparent" and then "confirm".

3) Now you want to reparent the bones one level down. (ie UpArmTwist needs to be parented from Clavicle to UpperArm, and ForeTwist needs to be parented to Forearm. To do this, hit "p" in schematic view to go into parenting mode. Then click and relesae on the twist bone so that it gets highlighted green. Then drag a line from the twist bone to the new parent, and it will create the hierarchy.

4) Do this for all four twist bones.

5) Now the character should deform properly when animated.

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