IK Handle problems!

[jaidek]

I have IK's set up on my character for only the legs (RP solver). The problem is, I'm making him do a "kata" in which some fantastic high kicks will be performed. Everything is coming out ok, except that for one of the kicks (high roundhouse kick). Coming down, the "twist" value of the IK has to be tweaked to get my desired position. The problem is, as the foot comes down, the leg flips almost instantly between frames but the twist value changes by only a few degrees. If I tweak another key to the desired position (usually about 200 or so degree's from the last key frame), then it assumes the twist is supposed to "ROTATE" completely around. I can't figure this out!!! And I can't afford to start over using only forward kin.

Also, what is the benefit to using IK's? I've only had trouble with them!! The only use I can see is for doing basic walk cycles or anything similar for the legs. Other wise, they just get annoying. I would really like for someone to prove me wrong!!!!!!!!!

Thanks

[ibutter]

you are using IK RP for the leg...
have you pole constrained to a locater and placed it up high and in front of the hip? then key frame it a little back when the leg does 200 degrees...
IF you modify your twist remember to reposition your (pole) locator to compensate. You should be able to only have to use the pole constraint
(if you have to: place the twist in the (pole)locator.. add attribute+connection editor... just to save time..but again, you shouldn't need to use twist too much with the pole constraint)

IK benefit?
my question: ever have to keyframe an entire FK character animation.... : )
i couldn't give up IK spline if i wanted to. the trick is to know which to use and when... FK or IK...

ibutter

[mads-tuxen]

what is the difference between using the twist-atribute and just rotating the ik handle it self (or the box-parent)?

Are they connected and doo you know of problems related to just using the twist?
The reason i ask is that im animating a caracter that has been set up with an ik handle to control the head and the twist atribute to turn the head, and it flips sometimes. The locator wich has the flip attribute is not parented to the root or sceleton so i use values as high as 1000 and more because of cirkular movemens.

Thats a lot of words! Hope you can decipher them

Mads

[ibutter]

a lot more words:
as far as i know..
if you rotate an IKRPsolver handle nothing changes (this is because it relies only on position and has twist and polevector for orientation).
on single chain solver (IKSC) rotate works but not twist (since this is based of the orientation and position of the handle). so you don't have a choice between the two on the handles.
IKRPsolver:
both the twist and pole vector rotates the joints. the pole vector and the twist are connected in someways. I find that if i'm animating the twist and pole vector together they compete and tends to get confusing to control. I use one or the other generally. twist for general rotation placement. for large movement of the joints the pole vector(because of possible flipping). i would imagine that you could use both for awkward fixes to joint problems.The one big difference is with the "pole vector" you can control flipping.. but not with the "twist".

i tend to hide my Ik handles.. parent them on locators, freeze the transformations of the locators, connection editor any "twist" i want to use.. all this in the name of bind pose! i don't animate them... rotate or translate.

your flipping head problem... are you using IKspline "twist" from the neck and/or spine. If IKPR, i would parent that locator for flips close to the head. so it moves with it.

i hope this helps...

ibutter

[mads-tuxen]

Thanks a lot Im sure i figure it out!
mads:)