IK/FK Solution

[rtorres]

Hi all
I have a big doubt.
I would like to have, for example, an arm with 3 bones with attributes to be controlled with FK (open/close arm), I would create a Set Driven Key for this.
In the same arm i also would like to have an ikhandle, so I could use the IK or FK solution.

[gmask]

I think what you want to do and it is a pain is to make three skeleton's One that is FK and the other is IK the third is constrained to the the other two. Then you make a control slider that gives you a percentage of the two controls.

The IK/FK switch doesn't seem to be as flexible.. it is an onoff value so when you turn on IK the skeleton jumps to that position whereas witha constraint you can transition into IK versus FK.

g

[ragtag]

In reply to:
I think what you want to do and it is a pain is to make three skeleton's One that is FK and the other is IK the third is constrained to the the other two. Then you make a control slider that gives you a percentage of the two controls.

When you constrain the third (mid) arm don't use orient constraints. They are euler based and are likely to go from one to the other in weird ways. Instead use an IK with pole vector on the mid arm, these you then constrain to the IK and FK arms (you'll need to make a small group parented to the elbow of the FK arm as a target for the pole vector).

An even better solution (but heavier on the computation...which is bad) is to do this on every joint of the arm. So that you have one ikHandle for the upper arm and one for the lower (for this to work correctly the lower arm ones all need to be in the same position). I'm working on a script that makes this kind of constraining easy, should be up on highen3d by monday.

Ragnar

[jnieder]

I would still try the rig out with the IK/FK switch. setting up 3 skeletons can be a hassle when moving between the 2 kinematics. The jump between the IK/FK that usually arises can be ironed out through the graph editor. I have not yet found an efficient way of handling this yet but I have accomplished and fluid transition. And it is much simpler than setting 3 skeletons.
JN

[tikimon]

In reply to:
I would still try the rig out with the IK/FK switch. setting up 3 skeletons can be a hassle when moving between the 2 kinematics. The jump between the IK/FK that usually arises can be ironed out through the graph editor. I have not yet found an efficient way of handling this yet but I have accomplished and fluid transition. And it is much simpler than setting 3 skeletons.
JN

what exactly is the ik/fk switch method?

:= TiKiMoN

[gaviez]

i have developed a setup and a mel script to have an ik/fk solution with automatic switching between ik/fk based on the selection...if you select the ik control, your in ik, if you select the upperarm or the lowerarm, your in fk. all the rotations are reported to the fk arm when you r in ik, and, the ik handle is constrain to the wrist when your in fk... contact me, i can be more explicit, but im a novice in mel scripting and i think there is lot of flaws in my script, this is why i havent post neither the tutorial nor the setup yet

gaviez

[tikimon]

if you switched from ik to fk, wouldn't you want to ignore the rotations? why update them in the ik handle? the reason anyone would switch is because the ik isn't solving something correctly. can't you just do ik, then fk to get the final pose, keyframe it, then go back to ik for the next pose?

:= TiKiMoN

[gaviez]

hi tikimon
sometime i prefer to pose my character with ik, sometime with fk... with this solution i can do that without have to switch with another attribut. moreover, i can choose to pose my character with ik for facility, but have an FK resolution for my arm an have those nice arc in my animation.
this is an emulation of character studio ik where you can use ik or fk to pose your character. i hate character studio for lot of things, but i like the way the animator can pose is character in this tool.

gaviez

[tikimon]

In reply to:
hi tikimon
sometime i prefer to pose my character with ik, sometime with fk... with this solution i can do that without have to switch with another attribut. moreover, i can choose to pose my character with ik for facility, but have an FK resolution for my arm an have those nice arc in my animation.
this is an emulation of character studio ik where you can use ik or fk to pose your character. i hate character studio for lot of things, but i like the way the animator can pose is character in this tool.

gaviez

cool... well, if this setup is as easy to use as you say, is there a way i can get a hold of it? this is the first time i've animated a character, and you wouldn't (or probably would) believe all the walls i've slammed face-first into during this whole process. somehow, i worked my way all the way to actually importing my character into the scene and preped for animation, but i'm finding it hard to pose him exactly how i want him with ik. i'm afraid if i turn off ik to pose and key him, then turn it back on to manipulate the arm generally to pose him again that it'll mess up my keys. is it possible to pose this way? (by "this way", i mean moving the arms generally by ik, then disabling the handle to fine-tune the animation, key the joints, then enable IK again to begin the next pose.)

:= TiKiMoN

[ragtag]

Hi gaviez,

Would it be possible to test this script you've written. It would be interesting. If yes, please Mail me at mel@animagicnet.no

Thanx,
Ragnar

[rtorres]

Hi!

Thanks for your help!

Rodri

[jschleifer]

this sounds pretty cool.. how does it deal with locking the hand, though? can you tell it when to evaluate ik and when to evaluate fk?

something which would be nice (the way I believe mirai does it) is to have the solver look at the end effector between frames. if the end effector doesn't move, then it solves IK.. if it does move, it solves fk.

that'd be pretty sweeet..

-jason

In reply to:
hi tikimon
sometime i prefer to pose my character with ik, sometime with fk... with this solution i can do that without have to switch with another attribut. moreover, i can choose to pose my character with ik for facility, but have an FK resolution for my arm an have those nice arc in my animation.
this is an emulation of character studio ik where you can use ik or fk to pose your character. i hate character studio for lot of things, but i like the way the animator can pose is character in this tool.

gaviez

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jason schleifer
animator
weta digital