Low Poly Shoulder Deform

Hi, what is a good work flow to solve a low poly shoulder deformation problem? The shoulder “socket” is only 4 edges. The red model is the same as the grey model. The red model just had its armature applied to it and its verts were positioned in a way to fix the deformation problem caused by the armature. I have tried using shape keys on the grey model but when I try to reposition the verts they move in unintuitive ways. I’m guessing the armature’s weights are influencing how the verts move in 3D space while in edit mode. As I attempt to reposition verts to fix the deformation caused by the armature should I have some settings on or off?

With only 4 verts per loop, you can’t afford any twist (nor do you have the resolution to display the difference between the inside and outside of an elbow anyways.) That twist-- the y axis rotation-- is the main reason for the problems you’re showing. Duplicate your armature, make the duplicate non-deforming, and have your bones damped track their counterparts’ tails, rather than animating the deforming bones directly.

There are different topologies that will do more for shoulders, but at 4 verts per loop, you can’t afford them.

The final thing is that arms don’t move like that. The arm cannot reach that position without the clavicle also rotating. Impossible poses will always look wrong.

1 Like

Hi Bandages, thanks for the help. I’m confused on how to have the “bones damped track their counterparts’ tails”. I should have two rigs, right. Rig1 and rig2. Rig1 has the mesh parented to it and has bones set to deform but it should not have any key frames? Rig2 does not have the mesh parented to it? The damped track constraint is applied to Rig1? It asks for a target which should be rig2? The bone the constraint asks for should be the shoulder bone of rig1 that is causing the deformation problem? Or should I use bone constraints (theses are remaining greyed out for me)?

You can (should) do it in one rig. Select all bones, duplicate, disable deform (and probably move to another bone layer.)

You can try it out on a single bone, just your upper arm, if you want, see how much it improves things.

It’s just a shortcut for animation, to keep you from giving the bones twist. You could do the same thing just by being very careful about how you rotate bones.

1 Like

Thanks bandages. In the armature’s viewport display settings I turned on axes for the bones and was careful about how each bone was rotating. That got me a good enough result without having to duplicate any bone and disable any deform or apply any damp track constraint.