Mesh "primvars:normals" is ignored

Omniverse Developer Tools & Resources Samples & Examples
1

Hi,
I was recently checking out the USD Mesh specs and found one spec I had missed.

https://graphics.pixar.com/usd/release/api/class_usd_geom_point_based.html#ac9a057e1f221d9a20b99887f35f84480

According to this, it seems to be possible to specify normals by “primvars:normals” in Mesh.

Reference : Please allow indexing of all primvars, including the normals · Issue #563 · Autodesk/maya-usd · GitHub

In usda, it can be written as follows.

normal3f[] primvars:normals = [(0, 0, 1), (1, 0, 0), ...] (
    interpolation = "faceVarying"
)
int[] primvars:normals:indices = [6, 9, 3, 0, ...]

Omniverse Create 2022.3 and USDView 22.11 do not reflect this and are treated as having no normals.

I have created a sample usda file.
primvars_normals.usda (6.4 KB)

Confirmation environment

OS : Windows 10

Omniverse Create 2022.3.0
USDView 22.11

Verification Procedure

  1. “primvars_normals.usda” is opened in Omniverse Create.
    primvars_normals.usda (6.4 KB)

Omniverse Create displayed the following.

primvars_normals_01
primvars_normals_01871×381 25.7 KB

USDView displayed the following.
primvars_normals_02
primvars_normals_02800×507 50.5 KB

2

Oh, I’m sorry!
I may have just left out the specification of subdivisionScheme = “none”.

uniform token subdivisionScheme = "none"

primvars_normals_with_subdivisionScheme_none.usda (6.4 KB)

Adding “subdivisionScheme = “none”” worked fine.