UnitScaleFactor is not referenced during fbx import

UnitScaleFactor is not referenced during fbx import.

Omniverse Create 2021.3.2

I have done some FBX import (Convert to USD) testing.
Since the fbx format has a fixed unit (default is cm), I checked two patterns.
Both are simple shapes with 1m Planes.

  1. [ fbx_unit_test_cm.fbx (10.8 KB) ] (ASCII)

    UnitScaleFactor = 1
    Vertices : 50,0,50,-50,0,50,50,0,-50,-50,0,-50

  2. [ fbx_unit_test_mm.fbx (10.8 KB) ] (ASCII)

    UnitScaleFactor = 0.1
    Vertices : 500,0,500,-500,0,500,500,0,-500,-500,0,-500

In this case, “fbx_unit_test_mm.fbx” did not convert to usd with the correct size in Omniverse.

It seems to be 10 times larger than the actual size.
From this, it seems that “Convert to USD” in the fbx file does not look at “UnitScaleFactor”.
This does not seem to be affected by “Use meter as world unit(cm by default)” in Import Options.

Some DCC tools had UnitScaleFactor = 0.1 on fbx export, and Omniverse seemed to load it at 10 times the actual size.

Hello @ft-lab! Thanks for reaching out. I informed the dev team about your post!

Thank you!

@ft-lab Thanks for reporting this bug. Yes, the scale is not respected during import. We’ll look into this and get a fix for it. Thanks for your patience.

Tracking Note: Development team has created an internal ticket (OM-37034)

@rozhang Thank you for the confirmation.

Hello @ft-lab, Just letting you know that the development team has updated this ticket to “In Progress”. Thanks for you patience as we work to resolve this issue.

@WendyGram, Thank you for keeping me informed of progress!

@ft-lab After internal discussion, we have no timetable about the solutions for this issue as the complexity of the problems. This is not only related with world units of child layers but also for reconciling all other metrics of child layers. We are working with Pixar and proposing solutions to solve this from root. You can find some details here:

@rozhang, Thanks for the report.
In fact, I saw something similar on Discord recently.
The usd metersPerUnit problem.

Indeed, I thought this was a very difficult problem for the USD format, which can have a reference structure.

After some research, it seems that I have the same problem when I convert glTF to USD.
( The units of glTF are standardized in meters. )