View Full Version : jason schleifer arm IK problem?

07 July 2003, 11:52 PM
i was watching my fast animation rig dvd. when i opend like final animation 4 i think its called, if i move jasons characters control on the wrist, it moves the arm cause the arm has IK, but also the wrist dont rotate it smoves from were its already posistioned. this is great becasue if like that hand is flat against a wall, and i bring the arm down the wall, its still going to be flat against the wall. does anyone have any idea how i can accomplish this?

my arm has ik setup in it right now, but when i move the control for my ik armthe wrist bends down depending on were i move it , it should just stay exactly how it is. thats what im trying to do i hope someone can help me out thanks

07 July 2003, 03:08 AM
I'm not sure how Jason does it, (havn't seen the DVD :blush: ) but I think you can acheive the effect you're looking for by adding another IK to the hand and parenting it to your hand controller. The way I do it is: I have a joint in the middle of the palm area which all of my finger joints attach to. I run the second IK from the wrist to this "palm joint" and parent it to the same hand/arm manipulator I've parented my arm IK to. This allows the hand/arm manipulator to control the hand's rotation simply by rotating it (no extra channels needed) and it allows the hand to stay flat on a plane even if you change the elbow's pole vector, or move the shoulder up or anything like that.

Hope this helps.

07 July 2003, 06:27 AM
hi mike, i took a nap, and i sware to you all 4 hrs of it was on maya stuff and how jason rigs his character, i was thinking about the spine when i woke up, thats all i remember. what you were saying sounds exactly likw what im trying to do. before i went to bed, i was thinking there must be like a extra joint in his hands, cause on feet if you parent it to like a reverse foot you get the same resutls. also in the model that is on the dvd, it does have this joint running through the hand like ignoring the fingers. im gonig to open the scene file and see if htere is ik in that hand. do you have a scene i can look at to see what you have done? i know its asking alot, but this is the one thing that isnt in the dvd/notes, besideds how he set up his back. but that is on the other dvd i think, and i cant find that right now, i spent like 20 min looking i have no idea were i plaed it im really worried.

07 July 2003, 08:05 AM
Glad to be of help...Here's a scene I threw together that will give you a very basic idea of how I set up my arm to acheive (what I believe to be) the effect you desire. This rig is lacking the extra forearm joint and a few fingers, but hopefully it'll help you out. It's controlled by four controllers: one for the wrist which moves the hand around (rotate/translate/fingercontrols). One that controlls the elbow (pole vector). One that controlls the shoulder (IK). And one to simulate the rest of the body. The heirerarchy (sp?) breakdown is not too complicated, and you should be able to easily see what I did in the Hypergraph or Outliner.

07 July 2003, 08:50 AM
hey space, thanks for the scene, im looking in outliner, can you walk me through this? sorry i know you pretty much did in your first reply, but all i can see is you parente d both your ik to your hand controler right? can you like walk me through sorry cause im so new to constraitns and all that im not sure what you have done really.

07 July 2003, 08:53 AM
i was guessing you had your hand controller hooked up to your ik in the connection editor, but i didnt see anything so im just confused now. ill try making this arm again by looking at your scene, it would be nice if i could just do it.

07 July 2003, 08:57 AM
bblast! thanks so much for this scene, ok this is what i did

i created ik from up arm to wrist, then ik from wrist to hand joint. then i made like a controller, i parented the hand ik to the controler, then the arm ik to the hand controller also right? i then made a constraint for the pole vector on the arm, so far this seems to be working, but i just want to make suere im not missing any thing thanks again.

07 July 2003, 04:55 PM
Why don`t you just orient constraint the wrist joint to the Hand_ArmController?

07 July 2003, 06:16 PM
Levitateme: You got it, that's all I did. The only extras I added were the fingers and shoulder. The fingers are just SDK set up with the channels I added on the hand controller. The shoulder is just IK with the IKHandle parented to a controller and the arm root joint parented to the shoulder/clavicle end joint (after grouping the root joint twice). This is by no means the only way to get this effect... in fact, it's probably not even the best way. Buexe's suggestion will most likely work just as well, but you'll have to make sure that your hand controller's local rotation axis is the same as your constrained joint, otherwise it'll flip out on ya. This is just a simple way to do it, but hopefully it'll help you out.

07 July 2003, 05:29 PM

There is two ways you can create a hand rig. One is to build the whole skeleton as one big unit. Like this:


If you build an IK handle from Shoulder to Wrist in this setup, you'll get the normal IK support, but guess what...Thumb is a child of Wrist, so it will orient according to the changes to wrist.

The second way to build a skeleton would be like this:


(where wrist is its OWN group)

Then you point constrain the Wrist to the Hand joint.

In this scenario, since you are only point constraining the Wrist to Hand, the skeleton will look the same, but the hand will not follow the orient of the rest of the arm.

Perhaps you've already figured this out, but I thought I'd respond for anyone else reading this thread who might have the same question.


07 July 2003, 05:42 PM
hi stzaske

thanks very much, i got the best replies on highend for how to do this. one way i dont even use ik. i tried it out and it works just the same, but i have got it stuck in my head yet. the second wayyou mentioned, i belive that is what jason does. he has a joint coming out of his wrist also . so you definatley are on the same level of thinking as him. but im going to try using your method, i just this ill get better results using ik in the hand anyway. thanks

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