Rigging Question (Shoulders/Clavicle)

Alexastor

I hope I'm posting in the right place.

I'm working on generic male lowpoly character (<1000 tris) in 3ds Max that will be used as a base for a couple of other male characters.

They will need to be animated, and to save time I want to use the same rig (using skin modifier) for all male characters, so animations can be shared.

Everything is working quite well, except the shoulder/clavice:


(Proportions reference by Andrew Loomis)

You can see a natural clavicle bone on the left and an adjusted one to the right.

• As you can see, the natural position and length of the clavicle wouldn't fit the model and would cause a lot of time and pain to skin properly.
• Rotated by 15° and elongated by 50%, it'd fit the model perfectly, but the bone wouldn't be "natural".

Are there any "best practices" for this? Would using the "unnatural" clavicle be a problem for animation?

monster

I typically use the blue side, but I keep the clavicle parallel to the ground. It helps if you use shared BIP animations or mocap files.

Couple more notes. You may consider moving the neck up a little. The length will feel awkward when you start animating. Also, your spine bones aren't taking the rib cage into account. I would either add a third joint or shorten the first one a little.

Alexastor

Thanks, I've shortened the neck back to standard size, shortened spine1 (chest) and lengthened spine (belly).

If the clavicle is running parallel, but as long as on the blue side, it won't match the arm or shoulder at all. Could you please show me an example what you mean?



Here's an alternative, where I shortened the chest even further to fit the parallel clavicle (green side) completely inside. Is that how it's supposed to rig characters? Thoughts?

Hirnwirbel

Way I see it (and I might be wrong here), I wouldn't worry too much about keeping the joints/bones exactly where the real bones are, unless you're setting up a film rig with muscles, realistic tissue deformation and all that jazz.

A real body moves and deforms in very complex ways that you cannot 100% replicate with a purely joint based game rig anyway, so your goal should be to get the best possible deformation with what you are allowed to use. If that means you have to place the shoulder joint a bit lower than it realistically would be, then so be it.
When I rig a model, I usually have a bit of a trial and error process going on... Place joints, quickly skin to them and see how things deform, then make changes to joint position or even topology as necessary.

Also: If your target bone count allows for two more bones, you might want to add a twist bone in the middle of the forearm. This will more closely mimic the motion of the radius and ulna when twisting the wrist and help avoid that pesky "candywrap" issue.

monster

You are very close to how I would create it. Hirnwirbel is correct, real human deformation is so complex that a few joints won't simulate it perfectly. Placing joints for the best mesh deformation is key.

Here's how I would do it. Note the clavicle is parallel to the ground, again because mocap is usually captured from a T pose and if you import mocap onto your skeleton this saves you from adjusting every single animation. BTW, you can just move the clavicle, you don't have to scale the spine joint to place it.

Also note the larger spine bone is on top. This is essentially the Rib Cage bone. In both of your setups the rib cage would bend which will look "wrong."

Alexastor

Thanks! What was I even thinking with the rib cage