9

456 Chapter 12: Animation
Rotational Joint rollout of the Hierarchy|IK panel.
This is usefu l for establishing a perfect match frame
(page 3–969) when transitioning b etween forward
and inverse kinematics.
Assu me Pref Angl es—CopiestheX,Y,andZ
pref erred angle channels of each bone and places
them into its FK rotation subcontroller. This
essentially per forms the inverse operation of the
Set As Pref Angles func tion.
Bone Joints group
Allows you to change the ends of the IK chain.
Pick Star t Joint—Defines one end of the IK chain.
Selectfromtheviewportorbyname(press
H ).
Pick End Joint—Defines the other end of the IK
chain. The direction of the chain is defined by the
hierarchy, not by Start and End Joint. Select f rom
theviewportorbyname(press
H ).
Wa rning: If you change the Start or End Joints so the IK
Limb Solver so there are more than two b ones between
the start and end, the solver will not work. Moving the IK
goal does not a ffect the bones.
Tip:
The order of the hierarchy determines the
direction of the chain. You cannot reverse the
directionofthechainbypickingBone10asthe
start and Bone 1 as the end.
IK S ol ver P roperti es R oll out (HI
Solver)
Select end effector of an HI IK chain. > Motion panel >
Parameters button > IK Solver Properties rollout
Her e are the additional controls for the HI IK
solver. The IK Solver Plane is controlled here
throughtheSwivelAngle,whichcanbeanimated
directly or using a target object.
In the Parent Space group you can choose to
whether the IK goal or the start joint will be used
as the parent space for the swivel angle. If IK
Goal is selec ted (which is the default), then the
Swivel Angle of the chain is defined in the p arent
space of its goal. If Start Joint is chosen, then the
SwivelAnglewillberelativetotheparentspaceof
the start joint. These two options allow a much
better control of the swivel angle on a chain with
two HI IK solvers. For example, the first solver on
the upper part of a chain can use a Swivel Angle
in the Parent Space of the Start Joint, while the
second IK solver on the lower part of the chain
uses the Parent Space of the IK Goal. In this case,
the change of the Swivel Angle for one chain won’t
change the orientation of the other one.
IntheThresholdsandSolutionsgroupyoucan
refinetheIKsolution.ThePositionThresholdsets
a limit in units of how far the goal can be moved
from the end effector , the Rotation does the same
in angle degrees.
The Solutions group Iterations is the maximum
number of attempts the IK solution will perform
before giving up.
If your IK animation seems to jitter, t ry increasing
the Iterations to 200. Increasing the Iterations w ill
slow down the computational time, but should
produce better results.
Ma nipulator for the Swivel A ngle
You can adjust the swivel angle with
the s pin ner in t his rollout, or you can adjust it
withamanipulator. Todoso,turnonSelect
and Manipulate (page 2–15).Theswivelangle
manipulator is displayed as a handle in the
view por ts.