2009

It's important to be aware of the following behavioral changes resulting from
this:
■ The three-DOF pelvis motion is displayed as three separate Euler or
quaternion (TCB) function curves in the Curve Editor and Workbench.
■ Using key reduction on the biped’s spine produces improved results.
■ Rotations on the new pelvic axes (X and Z) are keyable in layers and
supported in MAXScript.
■ The default parametric footstep animation is slightly adjusted to use the
three-DOF pelvis.
■ If a legacy biped asset such as a BIP file is loaded onto the 3ds Max biped,
the pelvis-related data will be adapted to the new DOFs and the new
coordinate space within which the pelvis rotates.
■ Using the Motion Mixer or Motion Flow, assets containing new pelvic
rotation tracks will be blended with old assets lacking these tracks.
Special Rotation: Elbows and Knees
Elbows and Knees perform a special rotation when you rotate them about
their X axis. They don't actually rotate around their X axis; this does not make
sense because they have one degree of freedom. Instead, the upper and lower
arm/leg are rotated together about an invisible axis defined by the line
stretching from the shoulder to the wrist, and the hip to the ankle. This special
rotation can be very useful for positioning the arms and legs.
The special rotation can also be useful for creating characters with reverse
knee bends. When the knees are rotated backward, at more than a 90-degree
rotation from the front-facing human knee posture, Biped assumes the
character has backward knees or bird legs, and uses this as a reference position
for all .bip motions.
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