IK with FULL control, is it possible?

#1

Hi!
How to take control over this spinning mess called IK in Messiah? :banghead:
I want to create an good IK chain for an arm, with FULL controll of the elbow direction.
I can’t solve it by FK-rotate the root-bone in Bank, cause it’s local coords is not working when IK is on!
And I cant use an extra IK-goal for the elbow-joint with a lower strenght, cause IK-goal-strenght is broken or not implemented. And the knee-constraint is not good enough, I cant control it with full precision. A character needs to be able to reach his armpit and still be able to point his elbow in any exreme angle, upp, backwards and so on.
I have contact Messiah support about this but have not get any response yet.

Mayas IK have one I love! It’s RotatePlaneIK and its PoleVector wich is perfect for controlling an elbows direction, if you ever have animate with it you should know what I mean, an if you have find a likewise good way to animate in Messiah pease tell me!!
I honestly dont think there’s nothing else to do than wait for an inproved IK-system in next Messiah, then maybe our animation-studio could work with this fast tool. :cry:

/ Svante

#2

err, have you checked the docs?
I’m really artsy weak in rigging, but this is one of messiah’s strong points - catering to tech wimps like me. Check the ‘knee’ constraint, or set a channel expression. Numerous other ways, maybe someone better at rigging will pipe in, but I remember there being step-by-step instructions in the docs. (Otherwise I wouldn’t have been able to do this.)

Have fun with the speed!

D.

#3

Yes I have read the docs…:rolleyes:

The docs also describes the IK goal strength wich I think never has been implemented, does anyone else care about this???
As I said in my first post, the knee-constraint is not good enough, cause I cant control it with full precision. That’s what I’m looking for, full precision.

And to all of you that think you can do it, have you ever done it?:twisted:
If you know how to setup an hi-precision-IK-arm please share your method with us!!!

A character needs to be able to reach his armpit and still be able to point his elbow in any extreme angle, up, backwards and so on.
Create a simple arm rig with IK that can be animated with FULL control of the elbow direction and the hand position!

Go ahead and show me!
/ Svante

PS. Dobermunk, thanks for the effort anyway!

#4

Hello,

I’m not quite sure I’m understanding the problem you are having. If the root of your IK chain is at the armpit, then you will have problems with flipping if the goal is moved too near it. AFAIK, all IK systems have this issue, known as the ‘critical area’.

I have just tried a quick test in Maya using a pole vector constraint and did not find it to correct this behavior, nor does it appear to work any differently than a KneeConstraint. Perhaps it would be best if you were to send me a Maya scene showing the chain working, and the equivelent setup in messiah where it is not. Then I can compare the two and hopefully help you better.

Ron Griswold (using Lyle’s account)
pmG
ron@projectmessiah.com

#5

Hi Ron!
I’m back at work in monday, it’s now friday night here in sweden, so I can’t send a file right now. But the point is not the ordinary flipping at that ‘critical zero point’, in Maya you should be able to come very near this point without flipping, but I can’t in Messiah, and IF the IK-plane flip in Maya, you can always correct it with the PoleVector.

/ Svante

#6

Hi svintaj,

I think I’m really only going to be able to help you out on this one if I can compare the scenes, so if you can send something on Monday, that would be great.

Thanks

#7

:wavey: File posted to Ron, waiting for a reply…

/ Svante

#8

Hi Svante,

I haven’t reveived that file. Please try to send it again to ron@projectmessiah.com.

Thank You,

#9

Strange!! :sad:
I have reposted it now…

/ Svante

#10

I obviously can´t reach PMG by e-mail :argh: so I re post my mail to Ron here. :shrug:

Hi Ron!

Here’s a Maya scene: www.vectorfilm.se/Temp/MayaIK.zip , where I’m trying to demonstrate the behavior I’m looking for, I can freely position the IK-goal in XYZ, and if the “elbow” flip or change direction I can easily correct it by keyframe the Twist-member of the IK-Null.
Press play to view the animation, look only in the Y and Z views to clearly see what I’m doing, I’m simply animate the IK-goal, and only keyframing Twist where I want to change the “elbow” angle. This IK-system have (what I call) FULL-control of the hand pos and the “elbow” angle.
And keep in mind that this setup takes less than an half minute to do in Maya!!

So, this has always worked great for mee in Maya, but in Messiah (and LW) I’m way to often come to a point, where I can’t correct the “elbow” angle, and then I have to go FK when I want IK : (

So my question is: How can I animate equally simple with IK in Messiah?? Can you duplicate this setup and animation in Messiah??

And one last simple question: Is IK goal strenght broken or not implemented???

I really look forward to hear from you!
/ Svante Segelson - Vectorfilm

#11

svintaj,

If I understand what your asking correctly, the kneeconstraint expression is an up-vector constraint and will give you FK control of the elbow while controling the arm via IK. I find using an armature an easier solution though. Look at the Armatures in Action video on pmG’s website

#12

bank the root bone in your ik chain.

I like to use a base bone that is parent to my ik chain, and bank that instead.

#13

Yes, it gives me control, but not “FULL-control”, or else I have never got it…:shrug:
But I think Messiahs IK is simply not as good as Mayas.

I realize that not everyone has Maya, but if you have, look at my MayaIK example : http://www.vectorfilm.se/Temp/MayaIK.zip, and then try to duplicate that setup and animation in messiah, cause I can’t!
And if you succeed you have the solution I’m looking for!:thumbsup:

Thanks fellows / Svante

#14

As I said in my first post:
I can’t solve it by FK-rotate the root-bone in Bank, cause it’s local coords is not working when IK is on!

Can you rotate in local coords while IK is on Joe??

I guess that is the answer to my last little quesion;)
I’m at home now, so I can’t try it right now, but I will.

/ Svante

#15

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