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Can Animation Retargeting cause performance drops (game)

I'm working on a project and this question is related to Animation Retargets and performance.

(Backstory) They have a dozen or so characters sharing a single Rig. (The Rig is the default 3rd person Mannequin Rig that you can export right from UE4) And apparently they have over 2000+ animations being used currently.

They asked me to come on after their previous Rigger left.

I'm tasked with using the Mannequin rig, which is an A pose. While the model is in an T pose, to get the character working with the Mannequin rig.

Looking at the Mannequin rig, it's not ideal for Rigging. It has a lot of rotations on the bones, the axises are all wrong, among other things.

I created a new one, using the ART toolset, weighted the character, Retargeted the Animation they sent me onto the new Rig. (Source = The Mannequin Rig, Retargeted Rig = My Rig)

Everything is working fine, but they tell me that they can't use this, because the Retargeting Animation would create duplicated Animations. Which would eat up memory and drop performance.

(Questions) (1) Does Retargeting Animation cause any noticeable performance drops in a Game? To take it to the extreme, if you have 10,000+ animations, and you bring a new Rig along. Retarget 2000 animations onto the new Rig, which would create 2,000 duplicated animations. Would their be more "memory" as they put it, used by UE4?

(2) If I cannot use the Retarget Animation, what suggestions could you give me dealing with rigging a T posed character with an A pose Rig?

Product Version: UE 4.15
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asked Sep 02 '17 at 05:02 PM in Using UE4

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1) No. Animations are not stored in RAM. It could complicate draw-calls I suppose but they are simply assets, not really a problem in that respect (not in any way I'm familiar with at least, I found the entire issue a bit odd).

2) If your T-posed character is deliberately posed with a rig then repose it to an A pose in your modelling software (make sure you get the orientations for the actual mesh as accurate as possible), remove the rig and import the mannequin skeleton into your modelling software would probably be the easiest one. Bind the mesh to that skeleton as you can directly work with skin weights etc to make sure it functions properly. If you don't have it rigged - Rig it and then repose it.

Alternatively I suppose you could create the mesh itself in an A-pose (or repose using a temp rig as mentioned), after which you could import the mesh and use the skeleton, but the skin weights would be really messed up.

Edit: I'm guessing you're using Maya right? Since you can import the actual UE4 mannequin skeleton into it, I would suggest using a HumanIK rig to pose your character over the UE4 skeleton exactly right, freezing transformations and then deleting the HumanIK rig. Bind the mesh to the UE4 skeleton as described.

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answered Sep 02 '17 at 07:49 PM

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Crowley Caine
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avatar image Shurkuris Sep 02 '17 at 10:13 PM

(1) Thanks for your answer, if anyone else to help verify. Does anyone know of any "performance drawbacks" when doing retargeting animation?

If I could convince them to just retarget their animations, it would save a lot of headaches. And give me the chance to utilize a proper Rig that is more ideal for animation.

(2) I was actually in the middle of posing the T posed character into an A pose. But it feels very janky to do, and would possibly require me to do some mesh-clean up. So I'll probably have to continue down this route

So, I wanted to check if anyone else has any good suggestions!

avatar image Crowley Caine Sep 03 '17 at 08:59 AM

Yeah I am in much of the same process myself at the moment. Because of difference in spine curvature, neck length etc it can quickly become an iterative process where you unbind/rebind several times to get it just right. Remember to delete all history and freeze transforms in the end to get rid of any joint orientation issues that might get stuck to your mesh.

I just don't understand why they can't give us a T-Pose for the rig, it's been requested for years. Although the A-Pose have a lot of advantages over a T-Pose, for amateurs and beginners the A pose is so much more difficult.

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