I have a question, on the Optitrack website under the Unreal Plugins section here https://www.optitrack.com/unreal-integration/
it says:
"Real-time full body animation retargeting
With full integration to Unreal Engine 4, IKinema LiveAction delivers the highest of quality solving and retargeting."
- So the plugin does not retarget

it goes onto say:
"Skeleton tracking data can also be integrated into Unreal Engine via a 3D retargeting process. This can be accomplished through a third party software that retargets captured 3D data onto a character to produce realistic motion in a scene..."
So, you need additional plugin Ikenema IKinema LiveAction for UE 4 to get skeleton retargeting.
But what's happening with IKINEMA? and more importantly, skeleton retargeting of Optitrack live data?
I heard they were acquired by Apple https://variety.com/2019/digital/news/a ... 358933/#!
Any ideas? Their website says 'Contact Us' and 'Documentation'. I have also written to Ikinema.