Export to USD - Scale units from Blender to Omniverse

[dcampillo]

HI,

I have a main issue while opening USD filed exported from blender. In my example, a cube (25cm wide) is basically 100x smaller than assets available in Omniverse Create?

Aside of rescaling things, is there a cleaner way to do it in Blender or at export time to USD?

Thanks,

David

[WendyGram]

Hello @dcampillo! Welcome to the Community! For clarity, so that I can help answer your question, are you using the Blender application (named the ‘Blender 3.1 Alpha USD Branch’ on the launcher) for your USD imports?

Also, I do know of a scaling issue that we are working closely with Pixar on. Here is a link to the forum post: UnitScaleFactor is not referenced during fbx import

Does this sound like the same issue your are experiencing?

[EDRobert]

I am using Blender 3.6 USD Branch for my USD Import and I just discovered this after adding a camera to the scene:

In Blender, this ferry is 15 meters long and the scale is 1.0.

Very disappointed that this can even happen.

[Simplychenable]

@EDRobert unfortunately, it doesn’t look like it’s an isolated issue pertaining to imported camera from Blender 😔 -

A few issues with cameras exported from Blender

Hello! I’ve been noticing a few issues with Blender cameras exported to USD (and imported in Composer): Imported cameras are huge. No matter if converted to cm or not. I think this also happens in UE5 but I’ll have to test that later. The camera is in the correct position, meaning the XForm scale is correct, just the camera “widget” is oversized: [image] I think this issue is related to this thread. Cameras that are not converted to cm during export have 100x smaller aperture and focal …

[EDRobert]

@Simplychenable

imported camera from Blender

Just to clarify, my camera was not imported from Blender. I created it in Composer and only then did I discover that my entire model had the wrong size.

[Simplychenable]

ah, i see. thanks for the clarification. it might still be relevant for you should you choose to import cameras from Blender at some point down the line. Also, not to confuse you, scales can be confusing if you don’t know where to look for them in OV. i briefly mentioned them in the thread below in case you weren’t aware of them -

A scale bug was introduced when you updated to Kit 105

Someone from NVidia, possibly Richard (sorry, that is all I remember of his name) mentioned this is a known issue. I am just posting this so I get notified or to make sure this is getting fixed. Prior to the latest Composer update, files from Blender or even Nvidia Assets all seemed to be the right scale. Now I get this message on almost every asset. You can’t see it in this picture, but the Billiard table was brought in from NVidia Asset’s tab. You have to increase the scale from 1 to 100 for…

this is just my opinion, but it’s probably a good idea to standardize your units between your CAD program and OV to avoid any scaling mishaps.

[EDRobert]

@Simplychenable

this is just my opinion, but it’s probably a good idea to standardize it between your CAD program and OV to avoid any scaling mishaps.

But that’s the job of Nvidia and Omniverse, isn’t it? There’s never ambiguity about scale in CAD ever, because it deals with real world objects.

Similarly, the Export USD button in Blender is made by Nvidia and since I know what the size of my objects are in Blender, I don’t think I should have to be uncertain about that when they end up in Omniverse. To me, that’s Nvidia not doing their job properly to be frank, since they are aiming at the digital twin market, and it must be fixed before we can adopt this piece of software where I work.