9

IK Terminology 437
program calculates the position and orientation
of the end of the chain. The final position of the
hierarchy, after all of the calculations have been
solved, is called the IK solution. There are a variet y
of IK solvers that can b e applied to a hierarchy.
Inverse kinematics starts with linking and pivot
placement as its foundat ion and t hen adds the
following principles:
• Joints can be limited with spe cific posit ional
and rotational properties.
• Position and orientation of parent objects are
determined by the position and orientation of
child objects.
Because of these additions, IK requires greater
thought about how you link your objects and place
pivots. Where many different solutions for linking
objects may be suitable for forward kinematics,
there are usually just a few go od solutions for any
given IK approach.
Inversekinematicsisofteneasiertousethan
forwardkinematics,andyoucanquicklycreate
complex motions. If you need to edit those
motions later, it can be simpler to revise the
animation if you are using IK. It also is the best
waytosimulateweightinananimation.
See also
Inverse Kinematics Methods (page 2–439)
IK Solvers (page 2–440)
IK Terminology (page 2–437)
Bones System (page 1–404)
Using Ob jects as Bones (page 1–410)
IK Ter min ology
Using inverse kinematics requires that you set
parameters for a number of IK components. Brief
definitions of these components follow; details are
provided in other topics.
Note: 3ds Max offers a variety of inverse kinematics
systems. There are four kinds of I K solvers, plus
appliedIKandinteractiveIKsystemsthatdon’t
use IK solvers. Not all of the following parameters
are used by all the systems.
IK Solvers—An IK solver applies an IK solution to a
kinematic chain. The kinematic chain is composed
of a bones system, or a set of linked objects.
Joints—An IK joint controls how an object
transforms with respect to its parent. You specify
joint behavior with settings in th ree categories:
•
Object P ivot Point—Thelocationofanobject’s
pivotpointdefineswherejointmotionis
applied.
•
Joint Parameters—Changing the IK settings in
the Hierarchy command panel determines the
direction, constraints, and order of how the
joint operates.
•
Parent Pi vot Point—Thelocationofanobject’s
parent pivot point defines the origin from
which the joint constraints are measured.
The commands you use to place the pivot points
for both the object and its parent are described in
Adjusting Pivots (page 2–423).
Sta r t and End J oints—The star t and end joints
define the beginning and end of an IK chain
managed by the IK solver. The hier archy of the
chain determines the direction of the chain. The
pivot point of the end joint is displa y ed as the end
effector, when end effector display is enabled.
Kinematic Chain—Inverse kinematics calculates the
position and orientation of objects in a kinematic
chain. The kinematic chain is defined as any par t
of a hierarch y under IK con trol. The IK chain
starts with a selected node and consists of a start
joint and an end joint. The base of the chain is
either the root of the enti re hierarchy, or an object