View Full Version : Jason Schliefer FK/OK back

05 May 2003, 02:19 PM
Hi guys, i've just wondering if someone can explain something about Jason Schleifer's FK/IK back on the A|W Character Rigging DVD. Basically, i know that the FK part is used to position the whole upper body and the IK part is used to mainpulate the spine, but do we need the 3 bones (4joints) for the FK setup as those bones don't really do anything special that i can see.

If you create a full body control then just parent the shoulder and hip controls under the full body control, then move the full body pivot to the root of the spine, this seems to do the exact same function as Jason's setup.

Also why do we need to create extra bones in order to set up the spine twist, when we can just create a new attribute can connect that attribute to the IK handle twist attribute.

I'm not very experienced with rigging, so i would really appreciate any feedback on this, maybe i'm missing something here!


05 May 2003, 11:09 PM
hi quyeno,

Exactly the same point i had, I see no point in having 2 spine rigs one just for giving the arc of the spine. Because you can do that with the ik rig. And as you say about the full body control thats the exact rig we use a work. hips,chest,head. chest/head and hips chest.

I see the reason as you want proper arcs in the animation, but i dont c need for an extra rig just to show this off. Also they both dont affect each, so u rotate the ik rig/cluster based and the fk rig stays as it is, so u get offset rotation of each other.

The rigs we use at work, are 3 and 6 bones setups for the spine. You have hip control and chest control, thats it. Twist is built in.


05 May 2003, 12:29 AM
hi eek, thanks for the reply. now i can present my project to my tutor with more confidence!:thumbsup:

05 May 2003, 09:14 PM
you certainly don't NEED the joints for the back.. I use them because some animators want to animate with an fk back, and others want to animate with an ik back.. still others use the fk to start with, then the ik to offset.

personally, I prefer the ik back on some characters, and an fk back on other characters.. it really depends on the creature.


05 May 2003, 10:24 PM
I started off using fk backs, but found i was always doing counter animation, as i wanted to keep the chest locked and just move the hips etc. As you say different characters suite different rigs.


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