Inverse kinematics is the process of determining the movement of interconnected segments of a body or model. For example, with a 3D model of a human body, if the hand is moved from a resting position to a waving position, how do the connected fingers, forearm, upper arm and main body move in response? It is a subject of programming and animating. It is approached often in game programming and 3D modelling.

An articulated figure consists of a set of rigid segments connected with joints. Varying the angles of the joints yields an indefinite number of configurations. The solution to the forward kinematics problem, given these angles, is the desired posture of the figure. The more difficult solution to the inverse kinematics problem is to find the joint angles given the desired configuration of the figure (i.e., end-effector).

For animators, the inverse kinematics problem is of great importance. These artists find it far simpler to express spatial appearance rather than joint angles. Applications of inverse kinematic algorithms include interactive manipulation, animation control and collision avoidance. Some of these solutions approach the problem via nonlinear programming techniques.

See also: Inverse kinematic animation

External links

• Inverse Kinematics algorithms (http://freespace.virgin.net/hugo.elias/models/m_ik.htm)
• Robot Inverse Kinematics (http://www.learnaboutrobots.com/inverseKinematics.htm)
• HowStuffWorks.com article How do the characters in video games move so fluidly? (http://entertainment.howstuffworks.com/question538.htm) with an explanation of inverse kinematics