Inverse kinematics, or IK, is a technique that calculates the required or optimal motion of a connected system of objects to arrive at a certain destination. In robotics, IK can determine how a robotic arm should move so that an actuator at the end of the arm is correctly positioned. In 3-D animation, IK can be enabled in animation software, so that movement of a child joint in a hierarchical character rig naturally affects parent objects.
For example, when animating a 3-D human character with IK enabled, an animator can raise the ankle joint of a character, and the shin, thigh, and knee joint naturally moves and rotates.
The opposite of inverse kinematics is forward kinematics, where a hierarchy of objects must be manually animated from parent to child. Forward kinematics could animate a leg, rotating the thigh at the hip to raise the knee, and rotating the shin bone at the knee joint to position the ankle.
Actuator, Animation software, Hierarchy, Rigging, Software terms
