Transmission

glTF extension: KHR_materials_transmission
glTF properties: transmissionFactor · transmissionTexture

Transmission controls how much light passes through a surface (e.g. glass, thin plastic). Requires KHR_materials_transmission to be enabled in the export options.

Shader	Attribute	Notes
standardSurface, aiStandardSurface	transmission
openPBRSurface	transmissionWeight
StingrayPBS	not supported	-

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Factor only

Set the transmission attribute directly on the shader.

• standardSurface, aiStandardSurface: set transmission.
• openPBRSurface: set transmissionWeight.

Exports as transmissionFactor.

standardSurfaceaiStandardSurfaceopenPBRSurface

standardSurface factor-only transmission setup.

aiStandardSurface factor-only transmission setup.

openPBRSurface factor-only transmission setup.

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Texture only

Color space: Raw

standardSurface · aiStandardSurface:
  aiImage.outColorR  →  shader.transmission
  file.outColorR     →  shader.transmission

openPBRSurface:
  aiImage.outColorR  →  shader.transmissionWeight
  file.outColorR     →  shader.transmissionWeight

Exports as transmissionTexture. glTF reads classic transmission from the red channel.

Because glTF defaults transmissionFactor to 0.0, texture-only transmission export also writes an explicit transmissionFactor: 1.0 so the texture remains active in the glTF.

standardSurfaceaiStandardSurfaceopenPBRSurface

standardSurface texture-only transmission setup with file and place2dTexture.

aiStandardSurface texture-only transmission setup with file and place2dTexture.

openPBRSurface texture-only transmission setup with file and place2dTexture.

Note

Use outColorR, not outAlpha. If your graph drives the same Maya attribute via outAlpha, that belongs to the diffuse transmission workflow (see the Diffuse Transmission page).

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Factor + texture

glTF computes: transmissionFactor × transmissionTexture

1. Connect the texture outColorR → multiplyDivide.input1X.
2. Set the transmission multiplier in multiplyDivide.input2X.
3. Connect multiplyDivide.outputX → shader.transmission (or transmissionWeight).

standardSurface · aiStandardSurface:
  texture.outColorR  →  multiplyDivide.input1X  →  shader.transmission

openPBRSurface:
  texture.outColorR  →  multiplyDivide.input1X  →  shader.transmissionWeight

The multiplier exports as transmissionFactor.

standardSurfaceaiStandardSurfaceopenPBRSurface

standardSurface factor-plus-texture transmission setup with file and place2dTexture.

aiStandardSurface factor-plus-texture transmission setup with file and place2dTexture.

openPBRSurface factor-plus-texture transmission setup with file and place2dTexture.

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UV transform

file nodes: set repeat, wrap, mirror, offset, and rotation on the connected place2dTexture.
aiImage nodes: wrap, scale, and offset export natively; rotation requires a place2dTexture.

UV set: assign via Maya's UV Set Editor or UV Linking - see UV Set Selection for node-type differences.

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Notes

• Transmission is a non-color workflow. Always use Raw color space.
• Use grayscale transmission maps; glTF reads the value from the red channel.
• Pure optical transparency normally stays alphaMode: OPAQUE. Use alpha modes only for alpha-as-coverage workflows like masks or cutouts.
• standardSurface / aiStandardSurface use transmission; openPBRSurface uses transmissionWeight.
• StingrayPBS does not export KHR_materials_transmission.
• This page covers classic (specular/refractive) transmission only. Diffuse transmission is documented separately.