Dispersion

glTF extension: KHR_materials_dispersion
glTF property: dispersion

Dispersion models chromatic aberration inside transmissive materials - the splitting of white light into its spectral components (e.g., prismatic glass, diamonds). It is a scalar constant; no texture input exists. Requires KHR_materials_dispersion to be enabled in the export options.

Note

Dispersion is only meaningful on transmissive materials. Enable KHR_materials_transmission alongside this extension.

Shader	Attribute	Notes
standardSurface, aiStandardSurface	transmissionDispersion	Unitless dispersion amount
openPBRSurface	transmissionDispersionAbbeNumber	Abbe number (different attribute name)
StingrayPBS	not supported	-

---

Setting dispersion

standardSurface, aiStandardSurface: Set transmissionDispersion on the shader.

openPBRSurface: Set transmissionDispersionAbbeNumber on the shader. To make dispersion visible in Maya's openPBR shading, also set transmissionDispersionScale to 1.0.

Both export as dispersion. Only written when the value is greater than 0.0 (the default 0.0 means no dispersion).

Note

For openPBRSurface, transmissionDispersionScale = 1.0 is a Maya-side display requirement. The exporter writes only transmissionDispersionAbbeNumber to glTF dispersion; transmissionDispersionScale is not exported.

standardSurfaceaiStandardSurfaceopenPBRSurface

standardSurface dispersion setup.

aiStandardSurface dispersion setup.

openPBRSurface dispersion setup.

---

Notes

• Dispersion is scalar only - there is no texture slot.
• Only written when the value is greater than 0.0.
• standardSurface/aiStandardSurface use transmissionDispersion; openPBRSurface uses transmissionDispersionAbbeNumber. Both map directly to the glTF dispersion property.
• openPBRSurface may also need transmissionDispersionScale = 1.0 for the effect to evaluate in Maya, but that scale value is not exported to glTF.
• StingrayPBS does not export KHR_materials_dispersion.

---

Example: diamond material

A diamond has high transmission, strong dispersion, and a thick volume. The setup below uses the recommended attribute values - adjust them to suit your asset.

standardSurface / aiStandardSurface:

Attribute	Value	Notes
transmission	1.0	Full transmission (must be > 0)
specularIOR	2.42	Index of refraction for diamond
transmissionDispersion	10.0	Dispersion amount
thickness (Extra Attributes)	0.02	Volume thickness in scene units
gltfDoubleSided (Extra Attributes)	enabled	Render both sides

openPBRSurface:

Attribute	Value	Notes
transmissionWeight	1.0	Full transmission (must be > 0)
specularIOR	2.42	Index of refraction for diamond
transmissionDispersionAbbeNumber	10.0	Abbe number
transmissionDispersionScale	1.0	Needed for dispersion to evaluate in Maya openPBR; not exported
thickness (Extra Attributes)	0.02	Volume thickness in scene units
gltfDoubleSided (Extra Attributes)	enabled	Render both sides

Note

thickness and gltfDoubleSided are custom attributes managed by the plugin. They appear in the Extra Attributes section of the Attribute Editor and are auto-created on the first export.