2 different joint types in an IK skeleton setup?

# 1 03-03-2005 , 01:47 AM

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2 different joint types in an IK skeleton setup?

can somebody please explain the use/meaning of the 2 different joint types in an IK skeleton setup?

In an IK joint chain, there are 2 ‘joints’: the actual Joint (bone) and the IK FK Joint, one lying on top of the other.

But when i move the IK handle the 'other' joint doesn't follow. How do I solve this and what does it mean?

thanks
L

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# 2 04-03-2005 , 06:20 AM

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never mind figured it out thanks for reading anyway

the FK IK joint (bone) display is just for reference. You can turn it off in prefs>kinematics if it bothers you user added image

cheers
lori

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# 3 04-03-2005 , 10:35 AM

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different joint types in an IK skeleton setup?

love sky

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# 4 07-03-2005 , 09:27 PM

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I think that if you have the IK/FK blend option turned on and you move the IK handle to pose a joint, the FK sleleton position will stay behind since you didn't move it. The visible FK skeleton isn't an actual skeleton, it just represents the FK position. You can move the IK and FK skeletons then keyframe from IK to FK to get the best of both worlds when animating.

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# 5 08-03-2005 , 06:02 AM

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Yep, it's the result of an IK/FK blend.
There are actually 3 joint chains:
- brown/maroon for IK
- dark blue for FK
- purple for the resulting blend of the IK and FK

Just to elaborate on this:
It's usefull when u want to overextend a joint what the IK handle won't allow (e.g. for an arm or leg).
You'd better use Animate>Ik/Fk Keys>Set Ik/FK key on the IK handle (never on the bones!!) to animate your blends and FK. Both Ik handle and the joints need to be keyframed or else freaky things start to happen with your IK solver.

Steps to blend from IK to FK:
1. Set IK/FK Key on the IK handle when Ik Blend in Channel box is still 1
2. move timeslider
3. set Ik Blend in Channel box to 0
4. Rotate joint
5. Set IK/FK Key on the IK handle

Do your FK animation using Set IK/FK Key on the IK handle

Steps to blend from FK to IK:
1. Set IK/FK Key on the IK handle when Ik Blend in Channel box is still 0
2. move timeslider
3. set Ik Blend in Channel box to 1
4. Rotate joint
5. Set IK/FK Key on the IK handle

Before and after your FK animation, you could just use regular Set Key to animate. Though this is when u will see a dark blue FK joint chain hanging from the top joint of your IK.

Attached is an illustration from the Maya manual.
Using Maya>Animation and Character Setup>Character Setup>Skeletons>Blend IK and FK animation

Attached Images

Last edited by Eelco; 08-03-2005 at 06:37 AM.

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# 6 08-03-2005 , 06:15 AM

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thanks guys. i get it now! pretty cool!

for anyone else viewing this post, you can also turn off the display of the FK/IK bones (if it bothers you) in the preferences (Kinematics) section.

cheers
Lori

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2 different joint types in an IK skeleton setup?

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