Rhino 8 ignores roughnessFactor from glTF / GLB import

Rhino
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1

Hi,

I’m testing fabric models exported as glTF/GLB. The .gltf clearly defines roughness with both a roughnessFactor (0.9–1.0) and a proper metallicRoughnessTexture (PNG, green channel). Example from my file:

"pbrMetallicRoughness": {
  "metallicFactor": 0.0,
  "roughnessFactor": 1.0,
  "metallicRoughnessTexture": { "index": 16, "texCoord": 0 }
}

The textures are in the same folder as the glTF and load fine in other viewers

. In Rhino 8, however:

  • The imported Physically Based material shows Roughness = 20% by default.

  • The roughness texture slot is filled but disabled, so Rhino only uses the scalar 0.2 instead of the file’s 1.0 + map.

  • Manually enabling the map and setting the slider to 100% produces the correct matte look.

It seems Rhino’s glTF importer is ignoring either the roughnessFactor or the metallicRoughness map, and falls back to 20%.

Can you confirm whether this is a bug in the importer, or if there’s a specific export setting we should be using to get correct roughness values into Rhino? Also, will future Rhino 8 updates improve the glTF/GLB material import handling (roughness/metallic maps, extensions like KHR_texture_transform)?

Thanks!

CAN_1_SEATER.gltf (28.5 KB)

2

Hi Justas -

When I import that file into Rhino, I get a “Error importing file “[…]/CAN_1_SEATER.gltf”.” error.
That also fails on convert3d.org.
-wim