Eyebrows' Shrinkwrap Modifier method Snapping Artifacts

Support Animation and Rigging
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Hi, there!

Looks like I’ve had a blind spot about this Eyebrows Rigging issue for some time already. There are certain Cartoony Expressions that just cannot be achieved if these Snapping Artifacts are not solved! So, this is actually a grave issue!

Do you know this issue? Maybe you know an alternative?
Maybe not use Shrinkwrap Modifier?

I first thought it was a problem of the Eyelashes Meshes, because they were part of the Face Mesh (so they would be Targeted by the Shinkwrapping Eyebrows); but, I’ve made a test (Separated the Eyelashes Meshes into a different Mesh Object), but it turns out, even if that was one part of the issue, the problem persists, apparently simply because of the big Mesh Geometry cavity that exists in-between the Eyebrow and the Top Lid Crease (or Top Eyelid), and how that relates to the Control Rig with Shrinkwrap Modifier (see the clip).

I don’t know any content addressing this. But it should be pretty standard and I’m just doing the wrong way?

Thanks!

Also, as a reference of what would be a proper solution to Eyebrows Rig, check this out (you can note that at the beginning, there is even a presentation of 2D artwork, Character Drawing Expressions for the Eyes Region; so this is thoughtful development):

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Interesting problem, have you thought about maybe a different mesh to shrinkwrap the eyebrows to?

Like duplicate part of the forehead mesh, and extrude the bottom of that mesh out so there is no eye cavity. Then have the shrinkwrap target that mesh and disable it for render/view.

Just a thought,
Randy

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Thanks for the feedback! this is accurate idea indeed.

I’ve made a few tets, and a Forehead ‘Ghost’ Mesh, that is used as a Shrinkwrap Target, indeed can work for this kind of Eyebrows Setup, and there would be several approaches to make it work. Your approach sounds pretty feasible also, I wouldn’t have thought about that one.

Then, there goes deep-down the rabbithole…
Turns out the Forehead Ghost Mesh can even become dynamic Mesh Geometry, instead of static Mesh Geometry; and then it would Deform in synchrony with the Face’s Forehead Mesh through Armature Deform, with the same Vertex Groups Data/Weight Paint of the Forhead, BUT NOT having any direct or indirect influence from Eyebrows Deform or Control Bones themselves (otherwise it’s Depedency Cycle). Instead of using Shrinkwrap Modifier on the Eyebrows Mesh Object, Targeting the Forehead Ghost Mesh, certain Bones of the Eyebrows get Shrinkwrap Bone Constraint to that Target.

I found that the Shrinkwrap Modifier of the Eyebrows Mesh Object, is usually the main culprit of the Snapping Artifacts; although it is plausible approaches like the one you’ve proposed could prevent its chaotic behavior --at least for the most part. There is that alternative of exchanging the Shrinkwrap features, which is also appealing.

This particular technique exists in the Universal Sonic Mouth Rig; apparently it can also be employed in the case of a Forehead and Eyebrows Setups, but I wasn’t thinking this was possible because of previous failures, very long time ago.

In the clip below (it’s not completed Setup): we can see, the Shrinkwrap Modifier’s Snapping Artifacts have gone, and the Eyebrows can nearly ‘touch’ the Top Lid Crease Region, however, the CTL Bones of the Eyebrows sometimes suffer a little Repositioning due the Deforms of the dynamic Forehead Ghost Mesh (when I manipuate that Mesh), and also, Posing these Bones close to the Eye Hole is yet a bit limited (not enough Forehead Ghost Mesh there yet). This was made as a first test; apparently, I would need to extend the Forehead Ghost Mesh towards the Eye itself. I’m thinking beyond, maybe connecting all of the… Ghost Meshes present in the Face Rig? but this can be dangerous --needs further experimentaiton. Imagine the whole Face has a Ghost version of itself? Is that even cannonical/conventional? If that is, I had no idea about that.

There are certainly plenty of other alternatives, but I think with the available propositions, that should work out in the end.

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