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ragtag

Prefered spine controls

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A while back when Gollum was all the rage, there was lots of discussion in Maya circles of the spline IK rig used for his spine. And I'm curious to hear what people here like to use.

 

First, a quick explaination of that rig. In it's most simple form, the spline IK rig is simpy two controller objects (nulls or bones) on each end of a spline. When you move them about the spline maintains a nice curve between them. Some bones are then attached to the curve, which then control the geometry of the character.

Since it's a spline, it also means that the spine itself can stretch. In Gollum they had a warning system, basically an object that would turn red or green, if the spine got too short or long. I did a variation on it, where you could weight the stretching of the spine on and off, in addition to the warning system.

Some people liked to add a set of straight FK bones, which the other controllers were children of. This way you could animate the spine with normal FK, and use the spline IK controls on top of that as an offset.

 

The more conventional spine is a straight forward FK spine, where you rotate bones from the hip up. I've also done a variation of this, where I had a hip controller, but would then control the spine from the it's center, giving a kind of up and down FK.

 

We did a different one for the Joint Factory (a Maya righ I co-authored a while back), where sliders were used to control a straight FK rig. This way you get normal FK, but you get the option of setting up sliders for things like hip sway without having the head move, while still maintaining a straight FK rig. It did have some minor problems when a lot of different sliders were combined.

 

Even though I did most of these rigs in Maya, all of them are possible in AM and some of them would even work better there. I'm just curious to hear what other people like to use for a spine, and what ideas they have for how to rig one.

 

Cheers,

 

Ragnar

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I have made a spine which involves a bone for the pelvis and a bone for the back. I have the bones of the spine orient like the back control bone to varying degrees allong length.

 

Translating the back bone will translate the upper body using relationships. I get independant pelvis and upper body movement plus squash and streach. I also get to choose what the body looks like when the back control bone translates.

 

Oh, and I get the all important butt bone too.

 

Seems to work ok.

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I have the bones of the spine orient like the back control bone to varying degrees allong length.

 

I use the same method for the spine of my quadruped models. I also use this technique for the tail and neck. You can, starting at the end, apply *lag* to the orient like constraints for the tail. Same setup can be used for ears too. Works great.

 

David :ph34r:

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I have made a spine which involves a bone for the pelvis and a bone for the back. I have the bones of the spine orient like the back control bone to varying degrees allong length.

 

Translating the back bone will translate the upper body using relationships. I get independant pelvis and upper body movement plus squash and streach. I also get to choose what the body looks like when the back control bone translates.

 

Oh, and I get the all important butt bone too.

 

Seems to work ok.

Can you post a screen shot of what that looks like?

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Can you post a screen shot of what that looks like?

I am considering releasing the rig to the community once I am happy with it. If I do this then I will try and document it as best as I can. I can't honestly remember exactly how it works at the moment so I will wait before releasing it.

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These kinds of spines are called Schliefer spines by a lot of people, after Jason Schliefer, the guy who rigged Gollum (and I probably just totally mangled the spelling of his name too). They're immensly cool. You haven't lived till you've animated with a stretchy Schliefer spine. I'll never use FK for a spine again.

 

For our version, we had to do it entirely with constraints, because the TSM scripting language doesn't support complex relationships. So, in our case there are really three bones effecting the actual spine geometry bones. The Pelvis is the parent of the whole thing, the Torso is at the other end, and in between is another bone halfway up the spine. This other bone is suspended between the Pelvis and the Torso through Translate Tos and Orient Likes, and the spine is then attached to these three bones with a set of Orient Likes that hands off influence between the three all the way up the spine. Then, for stretchiness, we simply add a Translate To, with Compensate offsets, from every spine bone to the Torso and have the influence grow as it moves up the spine. That's all linked to a slider so that you can turn the stretching on and off.

 

One of the things I like to do with it is to completely ignore the Body bone--the one that moves everything--and just animate the characters position with my two spine bones. This is pretty cool, since you can do offsets between when the pelvis arrives at it's key and when the torso does. I think that's where rigging is headed--total isolation for everything. I really saw that taken to the farthest extreme with the Chicken Little rigs they showed at Siggraph.

 

--Raf

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For our version, we had to do it entirely with constraints, because the TSM scripting language doesn't support complex relationships. So, in our case there are really three bones effecting the actual spine geometry bones.

Raf, was this used in the original version of TSM, or just v2? I remember the crawl test video on your website that actually had a 'Gollum' look to it.

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The original Setup Machine did it in a very similar way. There have been a lot of improvements with v2 (stretchiness, for instance), but the basic principals are the same.

 

--Raf

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