how to rig in maya joints and skinning splash

how to rig in maya: joints & skinning

Want to know how to place joints correctly? Looking for an explanation for Maya’s skin weighting tools, like the new Geodesic Voxel bind method? Want a cheat sheet for bone placement? Keep reading!

How to rig in Maya: the video

Ok, start with this video, it shows the joint creation and layout process, explain the joint creation and editing tools, and then dives into character skin binding and skin weighting tools. I’m weighting the Elle character model, you can grab it here if you want to follow along, but the principles work for any character mesh!

Creating joints and joint placement

Creating joints is easy enough – we just use the create joints tool in our orthographic camera. The real trick, of course, is knowing where to place them. Joints don’t behave like our joints and bones.

For example, to capture the movement of the shoulder, muscles in the chest, back, and shoulder have to move in sync. A single Maya joint can’t capture a system that complicated!

What we have to do is a kludge – we create joints in places where people don’t have any. These are joints that sit in the middle of the femur, or the humerus! What are these?

Helper joints

The key thing to remember in Maya is that joints aren’t bones – not human bones, I mean. They don’t behave like our skeleton, even though joint placement usually mimics our skeleton closely.

The difference is that joints are just a point in space, and the verts that are weighted to that joint just rotate it around it, like so:

how to rig in maya: simple deformation example
the verts weighted white are following the middle joint as it rotates

the verts just rotate in a circular motion around the joint – exactly like the rotation gizmo itself, when we use the rotate tool. This is quite different from how our real bodies move!

This means that we have to fake a few things to get our 3D skeleton to animate like a real human body.

For example – here is an arm with helper joints, and one without:

how to rig in maya: elbow helper bone rigging and skinning comparison image
the topology on the lower arm is clearly broken – ouch

Both arms are twisted in a left to right motion. The upper arm, with the helper joint, looks fine. However, the arm without the helper bone deforms very poorly in the elbow area – not to mention that elbows can’t rotate side to side like that!

So the helper joints (usually roll bones) are placed in areas where Maya’s simple joints simply can’t move correctly. For example, there is a roll bone in the forearm, because that is the easiest way to capture the movement of the ulna and radius bones. We see similar joints in the bicep and thigh areas.

Next – skin weighting!

14 thoughts on “how to rig in maya: joints & skinning”

  1. Hi james,, maya is tryn to make me nuts,,, 1st, my maya paints on d vtxs nt on d faces as urs on dis tutorial, 2nd d values on my vtxs r nt coming up in d component editor, its flat zeros after all i selected dem, n lastly, wen i try to rotate a joint, d mesh gradually try to separate from d joint,d more i rotate d less d binding impact, bt for sum areas, d skin bind is fine,,

    1. The Paint Weights tool only functions on verts, that is normal behavior. Not sure about the other errors though, try deleting history on the mesh and then rebinding it to your root node.

  2. Hi James,
    Terrific video! My models are all clothed and have some questions.
    What’s the best workflow for skinning clothes? Do you delete faces on the body mesh that don’t see the light of day?

    When asked in comments at YouTube about how to handle shirts, you say: “try skinning them separately and copy skin weights from the body on to the shirt.” If you copy skin weights, should you skin the shirt with all the joints in the skeleton, or just joints that influence the shirt?

    Are there any pros/cons to rigging controls before or after skinning?
    Thanks much!

    1. Yes, delete the skin under the clothing. Unless you’re doing cloth simulation, you won’t need that geo.

      Skin the entire body first, then worry about creating the clothing. Once the body is done, you can copy weights onto anything that is derived from that mesh.

  3. Thank you, James. I finished going through the extended video the first time and love how you show how to use display layers to add influences to a skinned mesh.

    Do you have any thoughts about how a beginner should think about using Post or Interactive modes for normalizing weights when binding? You use the interactive mode. Do you ever lock influences while weighting?

    Again, great stuff! 🙂

    1. Thanks, glad you enjoyed the video Ric! Skinning with interactive can sometimes be confusing to beginners, because what you see displayed on the mesh during paint weights won’t always match the behavior you see when moving the model. This most often happens when you think you’ve weighted verts either 0% or 100%, but still see unexpected influences. In that case switching to post might help, but in general I stick to interactive with the paint weights and component editor to knock out problems like that.

  4. hello james.. i am about to purchase the extended cut of the modelling tutorial..i just want to know if the mouth of the character is modelled in a way that allows movement and expressions (like mouth sync.) before i purchase… the youtube tutorial is excellent,please reply as soon as possible.thanks

  5. Hi James
    First of all, thanks for the great video, I learned a lot from it. I’d like to know if you plan on making videos about joint controllers, both body and face. I’m particularly curious about controllers for the face. Thanks!

    1. I just published my first face setup video, see the downloads page. Not going over controllerscontrollers yet, that will be somewhere down the road.

  6. Hey James, I’ve used your modeling video twice now and I think it’s fantastic. I’ve rigged both models and I have a couple questions.
    A) Why do some rigs have an abundance of helper joints?
    B) I’m trying to get proper deformations around the hips and shoulders. Do you have a tutorial for more advanced rigging/scripting?

    1. A) Helper joints are there because Maya joints can’t replicate the way muscles actually work. They are ok in areas that are basically hinge joints – like the elbow – but they can’t handle complicated areas like the shoulders. Helper joints can ameliorate some of the problems, but a muscle sim is the only way to get real deformation.

      B) nothing like that yet, sorry.

      1. Thanks for responding, I appreciate it. So is the muscle system pretty new? I’ve heard that it’s not worth using unless you have a very muscular person. The female I’m rigging has pretty average sized muscles. On older tutorials I’ve seen people use scripts/controls that slightly tweak the mesh/helper joints between the shoulder joint and elbow joint which are weighted to affect the shoulder and blend shapes to correct the animation. I’m aiming for her to be able to stretch while maintaining a somewhat realistic look. Would the muscle system be a better more efficient way of achieving this?

        1. Muscle systems have been around for years. The trade off is really setup time versus desired effect.

          If your character isn’t making any extreme motions, or is wearing clothing, then a few extra helper bones will do the trick. Bare skin doing extreme movements (think the Hulk) – that’s when you absolutely need a muscle system.

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