View Full Version : rigging a tail

04 April 2006, 05:09 PM
Heya folks !
I'm having some problems figuring out how i should rigg a character, i'd like to hear insights from others regarding techniques and stuff.
The character is a comic/cartoon like spermatozoid, has no legs or arms, it's body is actually reduced to a head, neck/collar and a tail (and a little ponytail-like thing on it's head, but that's ok). Thing is, i've tried a couple ways to rigg the tail, but so far none have given me really the level of control i'm looking for over the animation. I've tried the spline IK, HI IK and Limb IK chains, the best i have so far would be using HI chains.
The tail is made of 17 bones, and i'm using multiple HI chains (three at the moment), so i get different controllers over the tail's motion, but i must say i'm having troubles animating it, and troubles with the swivel angles.
So my questions would be, would you use as much bones or less, what kind of IK chains would you use, what would be the best solution to get a good control over the tail ?
Anyone ? :)

Thanks !


*edit : forgot to mention that i'm using Max

04 April 2006, 07:47 AM
Cool Avatar! Magic Pockets, wasn´t it?

Anyway, I could imagine using a spline as a wrap deformer, locking the length and maybe adding some expressions, so that when you pull at one end the middle follows at 50% or falls into a snaking movement (something like a sinus curve)...

Non linear deformers also apply, a bend or a sine deformer could be helpful as well.

Is the character one-shot, like a commercial or a you planning to use him for a series of animations?



04 April 2006, 08:58 AM
Hello Chris, thanks for answering.
Indeed, the avatar is from Magic Pocket, cool game that was ! : )

The character is planned to be used in a short / video clip and supposed to be animated in various poses and situations (it'll be singing too).
The bend and local deformers might help, that's a good idea (been playing with a bend to create additional motion already). As for the spline part, i'm not sure of how this could be done (especially expressions).
Actually, what i have best so far uses three HI Ik chains over the tail, but i'm having problems with the directions the chains take and allow me to animate (is that clear ?) - maybe it's also that i'm having problems animating a tail !
(iv'e attached a shot of the rigg so far)

Anyhow, i'll try and see about spline wrap deformer and local deformers too, thanks for the input.


04 April 2006, 01:01 AM
what about fk?

04 April 2006, 11:28 AM
Heya, Eek thanks for inputs, and yes i for some reason did not think about FK.. and might give it a try. In the meantime i came up with a start of something that looks good, so i'm working on it, i guess it was more a problem of "how should i animate a tail" rather than the setup itself.
Thanks anyway, folks !


04 April 2006, 01:59 PM
I think you should try to us fk with orientation control, so you can control the tail with 3 to 4 controller. Will the character ever stand with it tail? if so, you might want to try fk/ik together.

04 April 2006, 03:20 PM
Depending on how fine of a level of control you want on the tail here's my suggestions. I'll post a video on a tail I rigged later on tonight if you wish.

-hybrid Spline IK FK set up. (not sure how it'd translate to Max)

This one's my favorite, you make a joint chain with a lot of joints on the tail, then you do a spline ik on them, cluster every CV in the spline curve created, then create an FK Chain and parentConstrain the clusters to the FK.

Pros: FK controls with Spline IK smoothness
Cons: you'd need an extra step to set up good twisting, and another one for stretching (both doable though)

-Plain FK.

Self explanatory

- Dynamic Chain. (also not sure how it'd translate in Max)

This one you'd probably want for the pony tail, consists of setting up a spline IK and then converting the spline curve into a softbody. You could also do it with Maya Hair if you were on Maya.

with the pony tail you're probably just better off with just FK


04 April 2006, 01:41 PM
lkruel (member.php?u=153892) is right on the ball here. Cnverting what he is talking about to Max in all cases is easy. For the pony tail if you want it dynamic you could use Flex, cloth dynamics, rope dynamics or hair, all depends on what you are looking for. If you want total control just an FK chain might be best and the similest.

For the body I would go with the IK/FK spline solution as you will most likely need to have the tail on the ground as that is what the character stands on, this is what I assume anyway. I have a setup for a spine on the second DVD that you could adapt for this, I don't do the FK part if it but that is easy but I should how to set up the spline IK portion but I don't use the Spline IK solver, I don't use it in Max or Maya as I find I can have more control over the twisting if I do it all with constraints.

You might want to go the other way with the spline IK/Fk setup though and have the IK drive the FK so that the FK can be used to tweek the curve of the character after spline IK has been used for the main posing. I'm doing with now in the spine of a character that I'm driving the IK with mocap data and then I can either animated the IK for correcting or the FK. You could also do an IK/FK blend system so that it is one or the other.

04 April 2006, 05:15 PM
Heya, thank you people for the answers, and good insight on FK/IK and hybrid setups.

To answer a couple questions, yes, the character stands on its tail at times, and at others it just uses it's tail to move forward (much like spermatozoids do - but this little guy here has it's head-part standing and looking forward, rather than in a "diving" position - which is actually a pain), so i do need to have control over posing the tail, and control over animating it in a sort of snake-like motion.

So far, i'm still using solely IK chains (two of them, HI), i won't say it's all good since i get some limitations, especially over twists and rotations, but i can still animate and pose the character.
As for the ponytail, it's got its own bones and IK chain as well, and a flex added to it; actually the ponytail was not really what i was concerned with in the first place, but now that you mention it, i'll probably look at it more in detail.

Fact is this is research/design right now, working on/off on it, so the more solutions i can test, the better (both for the character, and for me !). So i'll be looking in details at the solutions you guys have pointed, i did not even think about FK in the first place. If i get hard times i'll be coming back to you guys : )
Thanks a lot !


04 April 2006, 05:04 PM
Thanks PEN, =)

I didnt realize you needed it to say on the floor. In that case I would probably have a switch on there for when he's swimming and when he's planted on the floor.

I still think Spline IK would be probably the best solution though, but you might have a switch to turn the FK chain off, so the animator can just control the head in an IK fashion and then move some clusters around to get the curve he wants and remember to turn sticky on the IK.

PEN, how would you do a spline IK setup using constraints?

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