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View Full Version : Maya: IK's own switch or custom 3-skeletons setup ?


berniebernie
12-06-2008, 07:16 PM
I've seen a lot of people use the 3 skeletons to do IK/FK blending (IK setup, FK setup and the 'blend')

I've also been told that from version 2008 upward (or maybe 8.5) maya's IK switch is bug-free and should be used, as it is 'lighter' on the scene and certainly easier on the eye in the outliner.

Any thoughts ?

tonytouch
12-07-2008, 10:14 AM
hi bernie,

as far as i know , most people still use 3 skeletons in production ( as it is the-classical-way ) . i always used the the ikBlend-attribute in the ikHandle , to blend / from maya5 on , when i started maya , up to know ... i am not sure , what they changed in maya 8 or 8.5 or 2008 - but ikHandle-FK_IK_blending , was always a bit tricky - when it comes to connect the bones and the FK_controls ( in my eyes , best is to "direct connect" the rotations / but you can also use orientConstraints or aimConstraints with up-Object. once you found a way that works , everything works well - and - you dont have so many bone-chains in the hierarchy . ( i thnk it is just not so much connections and not so many constraints and blendcolor-nodes and stuff .. for me it is just easier in the ikBlend-ik_handle_way.

i remember the first ikBlend-tryouts with my arm and leg-setups ( in maya5.01 ) ... were abit difficult , as there have not been any tutorials for ikBlend-attribute , and in the beginning i had many flipping_issues , as i did not use it correct - but in the meanwhile , nothing like that occurs anymore , everything works very symmetrical and its just pretty simple .

1. draw a skeleton
2. orient the joints
3. add the ikHandle + polevectorLocator
4. add 4 controlCurves ( 2 FK / elbow + ikMover )
5. parent ik to ikMover_CON / elbowLocator to elbow_CON ( regular IK_Method )
6. parent each FK_CON to the upper / lower arm joint ... zero out their transforms , unparent them and group them into *_NUL-groups ( so they are zero )
7. parentConstraint the lowerArm_FK_NUL to the upperarm_FK_Control ( so the lowerArm_CON_NUL will follow , whenever the upperarm_FK is rotated
8. connect the rotation of both FK_CONs to the bones ( now you have it all done )
9. add a "shape" with fkik_blend_attribute to all of your controls / connect the fkikBlend-Attribute to the ikBlend ( you might want to use a reverse-node here / if you want the blending to be from 0-10 , and not from 0-1 ... you can remap the attribute ("createNode remapValue;") additionally )
10. use input and ouptu of the reverse-node - also to connect the visibility (overrideEnabled / overrideVisibilty) of your CON_shape_nodes ... so this way , e.g. IK will be visible only , when in IK_mode , or FK , when in FK_mode .


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a friend of mine told me , that in production , it is different from project to project - one senior TD , wants the complete pipeline to be 3-skeleton-setups , and another senior TD , decides , in a different production , it will be done with the ikHandle-blending . best is propably , to know both methods . ( depends on your seniorTD and the project )

in my eyes , there are no really benefits , wheather you do it the one way , or the other way around . some people argue , it is better with ikBlend ( and use the ikSwitching of maya ) - but in my eyes , you need your custom-switching scripts anyway - so in my eyes i thnk , 3-skeletons are "the-classical-approach" , ikBlend is the newSchool-way ... but might be not so well documented ( tutorials ) and might not work so well for some people .

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@all:
pretty interested in some opinions about this topic ... please tell your point-of-view / which way do you use and why ? id also like to know , about PRO and CONs here and there

Leffler
12-07-2008, 11:22 AM
I have used the 3-chain method earlier but uses Mayas built-in IK/FK now

The 3-chain method just slows down the rig to much for my like.
Say you have 3-chains in arms, torso and legs. That is alot of constrains, alot of SDK for the switching and it just slows down the rig to much for my liking. Lots of constrains seems to be the worst enimy to fast rigs is my experience

Mayas built-in IK/FK isnīt to bad once you understand it

//Otto.

berniebernie
12-07-2008, 12:31 PM
Thank you for your opinions !

I'm still in school and it's up to me to choose which method we will use for our short, and I think I will stick to maya's IK/FK blend. It seems to work, and I do not plan on animating frames between the blends.

But as tonytouch mentionned, please explain your choice in the matter if you feel strongly about it !

Thank you and have a good day.

EricDLegare
12-07-2008, 01:06 PM
I would advise that you learn the 3-chain method as well, because there is no way you can tell that you will be working in Maya for your entire career, so the more different methods you know, the best you are prepared for the future :deal:

berniebernie
12-07-2008, 01:21 PM
Ah of course.

I've done both, it's just I haven't been far enough in animation to know the problems downstream (which I'm guessing are mostly 'flips')

tonytouch
12-08-2008, 10:51 AM
@bernie :
i used the ikBlend-way for "any" of my rigs up to now , but really want to implent a "old-fashioned" 3-skeleton-setup in my autorigging-scripts ... up to now ,i never used the 3-skeleton-method

but you need to find out , which way is better for yourself

as Leffler said , if you have character rigs with e.g. 4arms and 2 legs ... including an autoshoulder-setup for the arms ... you would need 4x2 of the 3-skeleton-chains ( 24 ) and with the ikBlend-ikHandle it is just 8 joints ... i did not make performace-tests yet about - but i guess it is really a bit faster .

about the speed , it really depends on , if you use direct-connections or constraints . constraints are always very slow - blendColor-nodes ( for blending between the rotation of 2-bones , as in the 3-skeleton-way ) is very fast indeed. so if you try to avoid constraints - chances are good , that your 3-skeleton-setup is as fast as an ikBlend-skeleton . so i would not think about speed-issues in this particular case .

slow rigs are in most cases slow , because people use expressions instead of math-nodes ( e.g. for stretch-arms ) - or if they use hyperMeshParent.mel-constrainted clusters for face setups ( this really slows down .... 3-skeleton or ikBlend ( there should be no big difference )

personally I think ikBlend is the way to go ( for me this turned out to be my first choice ) if you have lots of arms and legs ... you can check out this tutorial (http://seithcg.com/wordpress/?page_id=30)

i thnk 3-skeleton-way , is the best choice , if you are new-to-rigging and uncertain about "flips" - also it might be easier to learn as there is more information on the internet ... and here is a 3-skeleton-video (http://www.highend3d.com/maya/tutorials/character/Seamless-IKFK-Arm-Setup-334.html)

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hm , about other software ... well i am not 100% sure ( as i never use these ) , but do these tools really use 3-skeleton-setups ?

XSI ... no , it has a very neat ikHandle .. from what i heard ,maya can't compete with
motionbuilder ... does it use "3-skeletons-per-arm/leg" ??? i dont think so - they have complex mocap-IK_stuff in there
houdini ... i guess it also a bit more modern-piece-of-software
endorphine ... next-gen-animation-tool ... probably has a next-gen-ik-solution
massive ... same thing , i guess - less bones is important here

MolemanSD7
12-08-2008, 04:09 PM
I've never really looked into the IK blending setup, because when I did it originally, I wasn't a fan. And so I've never really gone back to check on advancements. So, I know nothing about it really. Is it flexible enough to allow for ik fk matching, and elbow/knee pinning, or other advanced controls?

tonytouch
12-08-2008, 04:22 PM
with the "ikBlend"-blending , this all works fine ( same , as in 3-skeleton-method ) elbow_locking/pinning , blending from IK to FK ( or snapping - via script ) - isolation of controls and spaceBlending / animating pivots - just a bunch of methods , one needs to combine .

JamSession
12-08-2008, 10:48 PM
I use the 3-arm setup for the simple fact it is so easy to script extra gadgets that the picky animators always want.

It also allows you to isolate the extra gadgets, meaning if you need a feature for the IK solver, such as elbow pinning, you only need think about IK. With Maya's built in IK/FK, you could run into an instance where your IK gadget is messing up the FK mode.


If you just need a simple quick standard ik/fk switching solution, then there is nothing wrong using a built in solution. The second an animator says, it would be cool if the arm does...... Then I would recommend using a 3 arm blending solution.

berniebernie
12-09-2008, 09:26 PM
It also allows you to isolate the extra gadgets, meaning if you need a feature for the IK solver, such as elbow pinning, you only need think about IK. With Maya's built in IK/FK, you could run into an instance where your IK gadget is messing up the FK mode.

Good point !

Seeing as I'm also going to animate it, I guess I have the leisure to choose one. Seems like the 3-arm setup is a little more interesting, as long as you're not rigging a full IK caterpillar

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