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Same animations, lots of skeletal meshes

Hello,
I’m working on an RPG where there will be lots of skeletal meshes. Most of these meshes will use the same animations.

From what I understood, each skeletal mesh will have its own skeleton… which means that I have to retarget each animation for each skeleton…

Basically, this means that if I have 40 animations and 30 skeletal meshes, I’ll end up with 40*30 = 1200 animations. Which seems quite too much to me.

Is there any way to avoid such a mess? Am I missing something?

No. It’s how it is.

The skeleton is what determines the height of a character.

You wouldn’t have 3 different skeletons if you wanted to just add parts - say a tail to one character and wings on another.

In that specific case, they can all share the same base skeleton and just have extra bones that aren’t used between different versions.

When you start to mess with height in general and bone length in particular, that’s when the skeleton and animations need to be either made specifically of retargeted and properly adjusted.

As far as it being too much.
Probably. But the weight of a good animation is insignificant.

Bad animations have way too many frames making them hard to work with.

If you stick with the default of 30fps for the animation keys (unreal does the adjustment to 60fps for you and your animations will always look good regardless of actual FPS), the produced files are very light / you can have billions like AC (assassins creed) and its not ever a problem.

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Actually, no: from the animation retargeting documentation, under “How Does Retargeting Work?”:

Also with Animation Retargeting, there is no significant difference in performance between using retargeted and non-retargeted animations. The benefit of using animation retargeting is increasing the number of unique characters without having to create an entirely new set of matching animations which could seriously cut down on your animation memory budget.

So you should be fine.

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… when you retarget animations new animations for the retargeted skeleton are created… … … …

I get what you mean, but from the skeleton asset documentation:

An important feature of Skeleton assets is that a single Skeleton asset can be used by multiple Skeletal Meshes. Best of all, the bone hierarchies in each one do not need to be identical. They do, however, need to have the same general structure.

From @emmedand’s post:

But:

Which means they must have the same general structure. This means they can use share the same skeleton asset, and thus, share the same animations. When retargeting skeletal meshes that have the use skeleton asset, the retargeting is applied to the skeleton, not the animation.

These two videos are useful:

Plus documentation: Animation Retargeting | Unreal Engine Documentation, Using Retargeted Animations | Unreal Engine Documentation


So what @emmedand needs to do is have all the skeletal meshes use the same skeleton asset (which once again, doesn’t need to have a matching hierarchy), which will allow the animations to be shared between them all.

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It’s probably different characters that do not share a skeleton or he wouldn’t be here asking in the first place.

@midgunner66 and @MostHost_LA thank you for your answers, I have a better understanding of the situation now.

That’s great, at least, having lots of animations won’t be a memory problem.

This would be the best approach. I couldn’t find any tutorial on how to use the same skeleton on different skeletal meshes… so I assumed it wasn’t possible.

There are different characters with very similar skeletons (for example, a male base mesh and a female base mesh… or robots that can be bigger or smaller), but those aren’t the same exact skeletons (for example, the woman is slightly smaller than the man).

To use the same animations without retargeting and thus creating duplicate the skeletons have to be the exact same asset.

For robots, though.
Maybe you can make them all the same size, and then just use the scale parameter in engine to adjust.

The only reason for it is the convenience when you have to edit animations. Editing one instead of editing 10 of the same is probably a lot easier…

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The problem with robots isn’t about overall size, but about specific pieces size… like a longer arm. I guess many robots will require the retargeting…

Exactly.

I’ll try to use the same exact skeleton for as many meshes as possible… for the remaining ones I’ll use the retargeting.

The links I provided all say that skeletons only need to have the same general structure (naming & order of the bones) to share the same skeleton asset; proportions & additional bones don’t matter. For example, from the skeleton documentation, they list examples:

Retargeting is what you use to match the proportions (still using the same skeleton asset):

They’re all using one set of animations (i.e. the animations haven’t been duplicated).
I’m sure this is the way they do it in Fortnite; there’s a bunch of characters with different proportions & hierarchies, but I’m sure they all share the same skeleton asset (and thus, the same animations).

When characters can’t use the same skeleton asset, then you use a rig for retargeting:

With Animation Retargeting it is also possible to share animations between characters that use different Skeleton assets as long as they share a similar Bone Hierarchy and use a shared asset called a Rig to pass animation data from one Skeleton to the other.

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You are misreading and misinterpreting.
Have you ever actually USED the system?

Doesn’t seem like it given the fact you keep saying boneheaded things like

Proportions absolutely matter.
It’s why retargeting even exists. (along with mix matching nomenclature)

100% incorrect.
If you retarget something you get a second set of animations that are retargeted from the original.

The worse part is that I corrected you 3 times already and here you are insisting with incorrect assumptions that could possibly lead the OP and other readers to assume things that are absolutely untrue.

And what exactly makes you “sure” ?
I’m curious now, because the fact that you are sure without having ever used the system is just… magical…

I want you to take 5 minutes, grab the default character in a default template, open the run animation, and set up the re-target settings to “animation scaled” for all the bones.
That’s the same process that you would need to rely on to “ignore” (really it’s mitigate) different proportions…
Additionally, if you have an hour you should try and set up IK retargeting on a shared skeleton that has different base sizes via animation scaled - that’s a whole different problem of it’s own, but still something you should probably be aware of by doing.

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I’m fairly certain that OP has already read and understood the reasons behind my advice already.

You are the one trying to peddle stuff that won’t work right in an actual project.
Apparently trying to prove something, Just like for the forum page speed. Still not really sure why. Nor do I really even care… but then again I do work for a living…

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Enough is enough. I’m locking this topic.

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