View Full Version : FK and IK

04 April 2006, 11:26 AM
Hi guys i am just starting to try animating characters and i hear the term FK, but more frequently IK a lot. I know they stand for Forward Kinematics and Inverse Kinematics, but what does that actually mean?

Is there any good tutorials you know of that could help me understand what this means and its uses.

04 April 2006, 12:33 PM
Basically FK means that you will manipulate each joint in the hierarchy chain. The top joint will affect the joints underneath it and so on. IK (inverse) is the opposite. You manipulate the bottom joint and others in that chain will follow.

I always find this one a bit strange to explain. Creating some joints, and then rotating/translating/scaling them means you are affecting the bones via FK. Setting out those bones and adding an IK solver means you grab the end effector and manipulate that, giving you IK.

It's hard to explain, but really simple to understand! Play around with your software docs and a lot will become clear, also look into setting up a reverse foot. That should get you off to a good start.

Hope that helps, if it sounds messed up... Well... I suck! :)



04 April 2006, 01:19 PM
yeah let's say that u have built an arm, then if u are using FK to pose it, u will have to select and rotate the arm, then u will select the forearm and rotate it again to pose it, then u will select the hand to pose it also...with IK what u would do is to set an IK solver in the hand, and whenever u move that ik solver, the arm will follor in the same way as if u glue ur hand to an object and u move the object puppets being manipulated by strings attatched to their hands... hope that helps :)

04 April 2006, 02:50 PM
Alex's explanation is pretty clear.
If you need to visualize FK and IK and how they fit in a rig, this video ( might be of some help.

04 April 2006, 01:28 PM
gosh, reading all your replies on how 3dquakers is a good educational visual reference, I am going to have to try it out.

can I buy with paypal ?

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04 April 2006, 01:28 PM
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