Automagic shoulder...somehow

[mcc]

Hi,

(...I am no native English speaker...)

I am using blender 1.82a and the snapshot of Makehuman from the community repo on Linux...bleeding edge, so to say.
I use to import Makehuman characters via the import mhx function of blender (in opposite to the 'online' import via 127.0.0.1).


But my question is a more general one and I am not quite sure, whether it is a more makehuman or blender related one.

When animating an arm of a model, the character is able to lift its arm up to certain degree. After that, it looks like its
shoulder joint gets broken/dislocated. So the bone of the shoulder needs to be animated seperately.
When it comes to repeated motion of the arm (like waveing) this extra animation task becomes tedious.

Is there any way known to automate the moving of the bone of the shoulder in accordance of the height and moving of the
arm/hand ?

Thank you very much for any helping hand/arm/shoulder!
Best regards,
mcc

[bogdan666]

Maybe you could use some kind of constraints and drivers for the bones.

A better way would be to make shape keys and drive them by bone rotations, so you could achieve even better results.
For this you have to decide if you like to work with "preserve volume" checked or not.
Animations with arms from "a-pose" setting to "t-pose" setting look ok and require only minor adjustments (esp. armpit area definition/depth)

But animations, which go further up (above the t-pose level) become very difficult to master (concerning the shoulder deformation). That is, where shape keys come into play and where you need some anatomic knowledge of a real humans shoulder/armpit/clavicle area.
That's where I'm struggling right now, because I don't know how many shape keys I need (one main shape key or one for each axis) and how they should look like...

[joepal]

I think you might be helped by looking into IK combined with rotation locks. That way you can delegate the calculation of most bone rotations to an automatic resolution that includes only valid rotations and only have to animate one or two bones total.

IK is a bit messy in the beginning, but very convenient when you get it right.

[mcc]

Maybe you could use some kind of constraints and drivers for the bones.

A better way would be to make shape keys and drive them by bone rotations, so you could achieve even better results.
For this you have to decide if you like to work with "preserve volume" checked or not.
Animations with arms from "a-pose" setting to "t-pose" setting look ok and require only minor adjustments (esp. armpit area definition/depth)

But animations, which go further up (above the t-pose level) become very difficult to master (concerning the shoulder deformation). That is, where shape keys come into play and where you need some anatomic knowledge of a real humans shoulder/armpit/clavicle area.
That's where I'm struggling right now, because I don't know how many shape keys I need (one main shape key or one for each axis) and how they should look like...

Hi bogdan666,

( Currently I have no access to my computer...so it is kinda "theoretically" and "off memory" what I am writing... )

When I remember correcty: The shoulder bone is not part of the chain of bones, which builds the arm. The arm bone chain is parented to the shoulder bone only.
I tried a 'limit distance' constraint applied to the shoulder bone -- which does not work, since the shoulder bone - when trying to remain in reach of the hand (for example)
- moves up and lifts in turn the arm, which keeps the shoulde to remain in reach of.....
What follows is kinda "make human explosion"...

[bogdan666]

Right now I'm experimenting with reweighting of the shoulder area. With certain poses it looks better now, but one question remains. Why do we need two bones for the shoulder/clavicle area? Wouldn't one bone for the whole
area be enough like with DAZ Studio Models? After having done a quick one bone setup test, one bone seems indeed to be sufficient for posing. The whole secret is to weight the shoulder area to the shoulder bone and the upper arm area to the upper arm bone.

[mcc]

Hi,

since I am not at my computer at home and do not have the right to install software on this computer...
...could someone post a rig (mhx2) of a makehuman character without the mesh (does not be modelled
in any way...could be the default one). -- That would be nice, since I could experiment with it and the
installed blender, whether I could find some "mechanical" solution for this problem...

Thank you very much in advance for any...hrrrmmmm... rig

Cheers!
mcc

[bogdan666]

Here is the example model you requested (no slider moved,no topology, with default rig). It's packed in a zip file as this forum doesn't allow mhx2 uploads.

[bogdan666]

I was able to change the skeleton by merging the shoulder and the clavicle bone into one by manually editing a copy of the default.mhskel file.

Now the bones affected behave like in DAZ Studio, where there is only one bone in the given area.

The trick was to remove any reference to the clavicle and replace it with the shoulder one where necessary and the second trick was to replace the shoulder head vertex ids with the clavicle head ones.
In this case it was easy, but if you want a bone to begin in an "undefined/unchartered" area, where there are no vertex infos given (in the mhskel concerned or any other mhskel files), it is impossible to find out what those vertex ids are.

But here everything went well. The next step would be to change the weight file in order to remove any reference to the clavicle and to repaint the whole area for it to behave more naturally.
When I finish everything I will upload the file to the right place and now I'm putting it here temporarily as attachment .

[bogdan666]

Skeleton file has been uploaded as new asset.
It wasn't even necessary to remove the reference to the clavicle in the proxy weight files. It can be combined with any proxy, because it works independently.