Noticed a problem in Unreal Engine 5.1 - when importing FBX that was exported from software that’s using other coordinate system (in my case it was Houdini), rotations in animation have some imprecisions.
It’s calculated rotation for object as 89,996204 °, not as 90 °. Which may not sound much but in my case object was far away from origin so it was noticable.
Originally object has no rotation at all. The reason Unreal does that, it tried to convert Houdini coordinate system to fit Unreal and it needs to rotate object 90deg by X axis to achieve but I guess calculations precision isn’t perfect.
As a workaround I now disable “Convert Scene” at import and rotate object’s geometry by 90 deg inside Houdini, so no transform calculations involved at all.
Example FBX if someone would need to reproduce the problem (ensure to import fbx as Skeletal Mesh and check “Convert Scene”).
cube.fbx (19.1 KB)
Issue seems to be resolved in 5.5 but “Convert Scene” check during import is gone, so my approach won’t work in 5.5 as mesh will be rotated twice. Hopefully, imprecisions are resolved completely then.
