9

892 Chapter 14: character studio
degree of freedom, you mi ght later need to change
the axis constraint setting.)
To rotate the biped pelvis in all three dimensions,
refer to Pelvis as Ball Joint (page 2–892).
B iped M otion Constr ai nts
Some biped parts have special-c ase 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 R otates
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 R otating
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 R otating
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 have
Zonly
Pelvis as B all J oint
The pelvis can be rotated in all three axes: X, Y,
and Z. This ball joint provides three degrees of
freedom, improving the flexibility of animating
w ith a biped, because the pelvis gyrations are
isolated from the center of mass (COM) rotation.
This causes the C OM 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 body’s COM rotational space.
It’s important to be aware of the following
behavioral changes resulting from this:
• The three-D OF pelv is motion is displayed
as three separate Euler or quaternion ( TCB)
function curves in the Curve Editor and
Work b ench .
• Using key reduction on the biped’s spine
produces improved results.