Hey! I’m making a muscle & tissue simulation for a humanoid character. This is my personal project so I’m slowly experimenting with it. I feel it will take more time to make things right, but mostly I feel that movements and the overall look are getting close to what I want.
However, I’m having trouble with palms/fingers and wanted to ask for the usual approaches.

Contrary to other parts, with palms I try to put tissue directly on the bones. The movements feel a bit abnormal. Sometimes I can get an adequate look, but it still lacks the details and cleanness that I could achieve in other parts. I’ve tried many things, like putting the tip part of the fingers in the rigid group or limiting the shrinking substantially. It doesn’t seem to be “right”.

So, I’m curious about your experiences.
Maybe you skipped palms entirely to animate them separately/put them into the rigid group? Maybe you did find a good way to simulate it along with everything else? If so, did you use tissue directly on the bones or maybe you made an improvised muscle layer for the palms?
Would be happy to hear any experiences and ideas. Maybe I'm missing something. Thanks!

Extremities are usually animated separately and blended back onto the final quadmesh. Tissue simulation is typically avoided in these areas by either chopping them off, or grouping them into the rigid group. The rigid group will only help with constraining the points in finicky areas, or, where sometimes bones are intentionally penetrating the outer tissue layer.

However, if you are going to simulate hands/fingers, ensure you have enough of the Core layer present in these areas, and, that there is adequate weight in the @corefalloff attribute.
The Core layer is constrained to the muscles and bones and the attachment strength is modulated by the @corefalloff point attribute. The core layer is what will "follow" your bone animation most directly. The outer tissue layer is then constrained to the core, effectively animating the tissue from the inside-out.

Hey John,

Ive got a rigid group of hands, feet and head points. In the sim, the tissue is rigid there but the hands go completely floppy at the wrists and feet at the ankles! Weird behaviour. Any ideas how to stop that?

Do you have your rigid group enabled and specified on the tissue solver?

Do you have bones in that region in your second input?

My guess is that you don't have any hand or feet bones. You'll want to include them if you want your hands and feet included in the tissue sim. If you don't have hand or foot bones you'll want to cut the hands and feet off for your tissue sim, which is what is usually done in production as John mentioned above.

If you do have bones there, then have you tried increasing the rigid stiffness/damping ratio?

Hi Liesbeth,
May I ask for some tips, I am trying to create a nice look for the close up of animated palms of the hands. I want to get rid of "sausages" look that usually comes with the animated fingers.

I am using muscle transfer and simulation recipes as a base, removing everything below the chest, trying to move knuckles bones as closer to the skin, and adding resolution to Otis tissue (which so far gives bad results).

As far as I understand the anatomy correctly, there are no actual muscles on fingers, so should I go on with just fat and tissue layers?

Thanks

Bad results in what way? You'll probably want to reduce your Shell Volume Minimum Thickness from what it is in the recipe.
It should "work" without muscles, but you might want to add some muscles for improved behaviour, depending on what way your results are bad currently. Because of the scale of the muscles and fat in the hands is so much smaller than the rest of the body, it is not feasible to include the hands in the setup by default, so you'll probably have to make quite a few adjustments to get it to work. I haven't done a hand setup myself before, so I can't give tips off the top of my head, but if you want to send your file to SideFX support I can take a look at it.

Thank you so much Liesbeth, I've just submitted the file and a message to the support! I've left a few notes inside the Hip.

By bad results I've generally meant specifically increasing the outer tissue mesh resolution - it gave a crazy "air drag" effect on fingers even where the bones are.
Now I've adjusted the tissue a bit better but still it all feels too smooth, I wish to have sharp knuckles and metacarpals and may be even Extensor Tendons which will be a dream!

And my second biggest concern is that when we retarget animation to the Otto's rig, it doesn't match precisely (especially on fingers), I've tried to match as close as possible, but that still a bit off, and animators will have to redo the work after the Muscle sim (I've left more detailed note inside the hip). I just wonder if that's how it is today, or there's actually a solution for that?

Thanks a lot!

So I've had a look at your file and while I've managed to fix your bone animation (by creating boneCapture weights on the bones for your character's original rig instead of the transferred one from Otto), and got a bit more definition in the fingers by sculpting more definition into your renderable skin rest pose and increasing the tissue resolution, ultimately the Otis results I got weren't bad, just barely different to the original animation.

I found that what gave the best results was using a Wrinkle Deformer without any simulation whatsoever. I found the following settings gave decent results. If this is a one off shot, or one of a handful, I would recommend using this in combination with a Shot Sculpt node. Otherwise you can maybe paint masks to control the compression stiffness more precisely on different parts of the fingers, and/or a mask for the wrinkle scale.