The parent object of the biped is its center of mass, which appears as a blue octahedron near the center of the biped’s pelvis. The name of this object is the root name of the biped (Bip01 by default).
The center of mass is sometimes referred to as the COM.
Unlike other objects and biped body parts, the center of mass has three separate animation tracks:
These buttons can be used to select each track in the Track Selection rollout.
Using the Select And Link tool from 3ds Max, you can link the center of mass object to another object if you need to reposition an animation sequence. An example of this might be a surfer. You could create an animation of a biped running up and down the surfboard, hanging its toes off the end of the surfboard, and so on, and then link the center of mass object to the board. When you animate the surfboard, the biped animation would travel with it.
Because the COM is the root object in the biped hierarchy, it is the only object in the biped that can be linked directly to other objects in the scene with Select And Link. A different technique is used to make other body parts, such as feet and hands, follow other objects in the scene. See Animating IK Attachments.
The center of mass shadow object, the circle between the biped’s feet on the world plane, provides a sense of where the character’s center of mass is positioned relative to the feet. Another use of the center of mass shadow is to link objects to it. For example, a camera and camera target could be linked to the shadow object to follow the character.
