8

750 Chapter 14: Character Studio
To rotate the biped pelvis in all three
dimensions, refer to
Pelvis as Ball Joint (page
2–750)
.
B iped Mot ion Cons tra int s
Some biped parts have special-case conditions that
govern how you can transform them, as described
in the table and sections that follow.
Biped Link Link Name
Fre e A x e s
Comments
Center of
mass
Bip01
(default)
X, Y, Z Rotates
entire biped
Pelvis Pelvis
X, Y, Z
If feet are
planted,
adjusts legs
to keep
feet and
toes above
ground
Head Head
X, Y, Z
Neck Neck
X, Y, Z
Neck
orientation
does not
affect head
orientation
Spine Spine,
Spine1-4
X, Y, Z Spine
rotation
adjusts
overall
balance
Tail Tail, Tail1-4
X, Y, Z
Clavicles
RArm,LArm Y,Z
Shoulder
orientation
does not
affect clavicle
orientation
Shoulders
(upper arm)
R UpperArm,
L UpperArm
X, Y, Z Rotating
pivots from
shoulder to
wrist
Elbows
(lower arm)
RForearm,L
Forearm
X, Z
Hinge plus
special
rotation
Hips (upper
leg)
RThigh,L
Thigh
X, Y, Z Rotating
pivots from
hip to ankle
Biped Link Link Name
Free Ax es
Comments
Knees (lower
leg)
R Calf, L Calf
X, Z
Hinge plus
special
rotation
Hands R Hand, L
Hand
X, Y, Z
Feet R Foot, L Foot X, Y, Z
If feet are
planted,
adjusts legs
to keep
feet and
toes above
ground
Fingers Finger0, 01,
02 Finger1,
11, 12, amd
so on
X, Y, Z
Finger bases
have three
free axes;
other finger
joints have Z
only
Toes Toe0, 01, 02
Toe1, 11, 12 ,
and so on
X, Y, Z
Toe bases
have three
free axes;
other toe
joints h ave
Zonly
Pelvis as Ba ll Joint
The pelvis can be rotated in all three axes: X, Y,
and Z. This ball joint provides three degrees of
freedom, improving the flexibilit y of animating
w ith a biped, because the pelvis g yrations are
isolated from the center of mass (COM) rotation.
This c auses the COM to assume a smoother
trajectory, which also influences the biped’s head
and arms. As a result, they will look more natural
moving in the b ody’s COM rotational space.
It’s important to be aware of the following
behavioral changes resulting from this:
• The three-D OF pelvis motion is displayed
as three separate Euler or quaternion (TCB)
function curves in the Curve Editor and
Wor k b e n ch .
• Using key reduct ion on the biped’s spine
produces improved results.