erich666 / mcusd Goto Github PK

Hello, great to see more USD resources coming online.

Right now for Blender materials to be imported at all, you'll need to enable the following option during Import (in the Experimental section):

That should hopefully end up with something along the lines of the following for a render:

Do note that there's some known issues around translating the USD PreviewSurface into the Principled BSDF, as is currently done. But definitely let us know if you run into any further problems over at:

• https://blender.chat/ (channel pipeline-assets-io-module)
• https://developer.blender.org/

Per the following in the USD spec, the Camera should be defined in "1/10th" units, because USD is just... wonderful :)

https://graphics.pixar.com/usd/release/api/class_usd_geom_camera.html#UsdGeom_CameraUnits

...
We do make a concession, however, in that lens and filmback properties are measured in tenths of a scene unit rather
than "raw" scene units. This means that with the fallback value of .01 for metersPerUnit - i.e. scene unit of
centimeters - then these "tenth of scene unit" properties are effectively millimeters.

I believe this means that the current camera values are 100x too big due to the used metersPerUnit = 1

Things might "look" ok because the ratio between the values is similarly off, but as more apps start respecting that part of the spec, the actual values are going to be very strange. Blender's importer will soon start using 1/10th, and after that fix the McUsd.usda model will load with a focalLength of 1.8 meters instead of 18mm for the camera which is hilarious :)

This is fascinating, and lovely work!

I am very curious about the alpha mode problems in the Storm render. Over here (https://github.com/usd-wg/assets/tree/main/test_assets/AlphaBlendModeTest) we've built an Alpha Blend Mode Test that identifies similar issues and I am wondering if you might have discovered more blending issues? In particular I notice that in our tests, the blending behavior on Omniverse is as far as we can tell not right versus the "reference" ground truth image, but nearly every renderer we have tested so far has some degree of incorrect behavior.

Would it be possible to pop our reference usd file in to your scene to try to narrow down where issues lie? I think there may be bugs to file against the Storm based on the odd rendering of the sunflower, but it would be good to have canonical reference so we all push consistently in the same direction and make sure we don't introduce new bugs.

We are also open to the idea that our blend test asset might be incorrect, and would definitely appreciate more eyes on it.

BTW, I'd like to invite you to pop in to a USD working group meeting to say hello and maybe show off your work a little :)