Interchange missing 'Preserve Local Transform' Option

Development Character & Animation
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1

Hello, I’m having an issue with the interchange FBX importer for Skeletal Meshes (created in Blender) where physics assets are spamming warnings around scaling. I was able to fix the Scale issue by using the older importer that has ‘Preserve Local Transform’ as an option to turn on. My question: Is there a way of enabling the ‘Preserve Local Transform’ option for the newer interchange importer or any plans on implementing it in the future? Thanks!

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Steps to Reproduce

  • Open Unreal Editor
  • In any folder, import an FBX of a Blender created character/ skeletal Mesh
  • Select Skeletal Mesh for the interchange preset
  • Observe no option for ‘Preserve Local Transform’
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3

Hey there,

Unfortunately, no, there isn’t a way to enable it, and there currently aren’t plans to bring it back. The primary reason is that the workflow is very specific to FBX, and we’re looking to simplify the importing workflows to support many types with interchange. What is the warning around physics assets and scaling, and would you be willing to share an asset that causes the issue?

Dustin

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4

Hey, so the main issue is FBX skeletal mesh files created in Blender (which I am not familiar with) from the animation team that are imported through interchange have micro or fractional scale issues; where the scale on the joints are a small fraction off from 1.0 Scale, say 0.9998 or 1.0001. I think this stems from how Armature in Blender works, but that is the extent of my knowledge.

In this particular case, there was a tentacle simulation on a skeletal mesh that had these micro scale issues and the log spams every frame:

FConstraintInstance::GetRefFrame : Contained Scale

Having delt with Blender source skeletal meshes before, I remembered that Preserve Local Transforms cleaned up transform scale, which it did and scale was now set to 1.0.

I’ll have to check and see if I can share the asset however.

Thanks!

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Thanks, if you can, that would be great. Ultimately, from what I can tell, if you’re setting up your scene in Blender with the appropriate world size and export options, you should be ok. I’ve tried replicating the issue on our side, but haven’t been able to.

On a side note, you can post-edit the skeleton in the skeleton editing tools inside of Unreal. If you see issues, you could fix them there as well.

Dustin

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