View Full Version : Character rig with constrained arms and spine/nick

08 August 2008, 11:22 AM
Hi there, I'm used to character rigging and have had a look around for tutorials that solve this problem for me without much luck, so I was hoping for some help please.

I was wondering if someone out there could point in the direction of a tutorial on how to rig a character to have arms and spine/neck constrained to the hips. As well as an option to unconstrain it from the hips without any jumping in position.

I realise there are scripts out there that do this automatically, however I really want to learn how to do this myself for more flexibility in the future.

Thankyou very much for helping me out on this one!

08 August 2008, 11:44 PM
Based on what you asked I assume that by saying hips you mean a pelvis. It may seem a little nitpicky but there is a difference. IE the knees are connected to the hips the hips connected to the Pelvis. It is simular to the Torso to Clavical to Shoulder. Proper naming based on human anatomy and mechanics really helps in rigging.

So that being said if you have a pelvis and want to attach a chain of joints that will be a spine system and a set of chains that are arms and likewise legs and would want the ability for the chains to be attached and moved by the pelvis and also be able to become seperated from the pelvis. Think of the five lions that form Voltron. Its relatively a easy thing to do, this may seem complex but really you will do the same thing 5 times, but a good understanding of rigging will help. The arms should be "attached" to the torso. The spine connects to the Pelvis and the hips to the pelvis as well. Make two attributes that are a float type named LeftArm and RightArm on the controller for the Torso with a min of 0, max of 1 and default at 0. Do the same to the pelvis controller 3 times one called Spine, LeftLeg and RightLeg. Then select the Torso and the Left shoulder and Parent Constraint with maintain offset on. Do the same for the right shoulder. Then connect the spine to the pelvis and the legs to the pelvis.

You then can Set Driven Key the attributes you made to the parent constaint weight values or use the connection editor to make the connections. That way when you set values in the attribute fields of 0 then the limbs will become seperated and the weight is turned off. Set the value to 1 and the weight is turned on and the limbs will stay attached. Move the Pelvis and the Spine and legs go with it and the arms go where ever the spines torso goes. As well you could attach a neck and head to the Torso this way, or wings, or anything else you might need.

This type of rig you want or need is what is referred to as a Broken Hierarchy. You have several small chain systems connected to form a larger system. If you can Gnomon Workshop has a really great rigging dvd called the Puppet Rig that you should pick up if you can. It goes into how to make all the small chains like arms, legs, spines and necks and how they all connect.

08 August 2008, 01:35 AM
I think the term here is space switching. Are you talking about temporarily constraining your arms to the pelvis or root, as if a character was holding his waist, and then have the arms free again?

I haven't really delved into this type of functionality, but I found these interesting sites:


08 August 2008, 04:32 PM
I'm basically wanting it, so that when I move the Manipular that controls the Pelvis/Hips, that the arms will move exactly with it. (Like a real person, if they bend down, their arms will move perfectly down with them)

On top of that, i'd also like to have the ability to remove that constraint without any jump in the animation, so that I could place the hand on a wall, and when the pelvis/hips manipulator is move, the hand will stay where it is.

Does that sound like something the dvd you suggested (the puppet rig) would cover, and is it the best dvd for what I want to do?

Thanks for your help.

08 August 2008, 05:17 PM
Wow that is actually something different that you want. Thanks for clarifying. You could try an Orient constraint between the shoulders, maintain offset as well. That way whatever angle the pelvis at the shoulders would move the same. Or you could Aim constraint the shoulders to some controller you can keep near the feet and move around. That way the arms will always look to the controller no matter what the pelvis does. So a person standing upright the arms are pointing downwards and if the character bent over to tie their shoes the arms would still point towards the ground as the pelvis and spine rotated. The aim constraint weight can be set driven keyed to a attribute you make to turn it off and on when needed.

I think that will get you the automation you want.

08 August 2008, 07:20 PM
Is there any tutorials I can buy or downoad for this? I would've thought what I wanted to do would be a very basic rig within the industry that there'd be tons of tutorials to follow.

08 August 2008, 08:42 PM
I would get the Puppet Rig dvd from Gnomon, you can download all their dvd's as well now. That dvd will guide you through to making a really nice rig with a lot of cool features (Fk/IK switching, stretch nodes, etc) and it has you do a lot of steps using the constraints in Maya. I'm pretty sure when you get done that dvd you have a good understanding of all constraints, rigging and character set up and should have no problem setting a Aim constraint on your arms to do what you are suggesting. If you really want to get advanced there is the Animator Friendly Rigging dvd's from Autodesk. That is a really good series and covers a lot of rigging but it is a bit more advanced then the Puppet Rig and a lot more expensive. And if you can pick up a set of the Art of Rigging from cg channel. The first one is out of print and hard to find but they now sell a ebook version of the first one, volumes two and three you can get hard copies. No rigger should be without those books within a arms reach.

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