I bet you are confused about FK rigging and IK rigging when you first saw these two words. But don’t worry! This blog, which helps facilitate animated character making process, will explain the concept and tell the difference between these two kinds of rigging. After learning this lesson, you will know when to choose FK rigging and when to choose IK rigging while you make your unique and awesome animated characters.
What are FK rigging and IK rigging?
FK is the abbreviation for Forward Kinematics. It refers to the use of the kinematic equations of a robot to compute the position of the end-effector from specified values for the joint parameters. IK, Inverse kinematics, is the mathematical process of calculating the variable joint parameters needed to place the end of a kinematic chain, such as a robot manipulator or animation character’s skeleton, in a given position and orientation relative to the start of the chain. In general, they are both the process of rigging by using animated character making software, Mango Animate character maker, for example.
What are the differences?
As for rigging process, you need to define the whole pose of an articulated body with FK rigging, so as to provide the algorithm with the pose input. But if you use IK rigging, you do not need to define the whole pose of an articulated body since IK algorithm will get it calculated automatically, so you just need to define a position as the input. For example, if you want to use FK rigging in Mango Animate Character Maker, you need to know what position you are going to achieve and figure out the processing movements that help the character achieve that particular action. Then you should adjust the movements frame by frame, which may cost a lot of time if the defined action is complicated. But if you use the IK rigging, you can drag directly the available action that has been made previously to the character and you will get the dreaming character in a short time.
In terms of animation effect, these two kinds of rigging differ in whether the parent bone would control the movement of its hierarchy ones. In an FK rig, each bone follows the parent bone’s behavior, that is to say, if you move the parent bone, the whole skeleton will move and thus the whole body move, which may make it difficult to control the action, especially when there is some part of the body that needs to be still. However, if you use IK rig, you can control both the dynamic part and the static part. Mango Animate Animation Maker provides its users the IK rigs function, which is more convenient for them to create the awesome characters and more flexible way to control the character.
So, these are two main points about the differences of these two kinds of rigging. Simply saying，Inverse Kinematics is the inverse algorithm of Forward Kinematics.
When to choose FK rigging and when to choose IK rigging?
The answer is quite simple. We choose tools according to their function and our own needs. If there are certain areas of the character that needs to act together, then it might be suitable to use FK rigging. If there are parts of the body that needs to move more flexibly, then you may choose IK rigging.
In Conclusion
The purpose of using FK rigging or IK rigging is to make the most awesome character you can. FK rigging needs you to be more patient as there may be more work to do to rig the characters. IK rigging as in Mango Animate Character Maker is more convenient and flexible since the rigging work is mostly done by the IK function and you can control the character more arbitrarily.