Material outputs

Aqueduct graphs may expose any output name.

However, the following outputs are recognized by Aqueduct and will be automatically interpreted by the in-editor material preview and Unreal material packaging as follows.

Aqueduct output	OpenPBR input	Interpretation
base_color	base_color	Diffuse color for dielectrics. Normal-incidence reflectance for metals.
height	None	Surface displacement, with 0.5 as the neutral level.
normal	geometry_normal	Tangent-space base normal using the graph's normal format.
roughness	specular_roughness	Microfacet roughness, from 0 (smooth) to 1 (rough).
metallic	base_metalness	Mixes dielectric (0) and metallic (1) response.
emissive	emission_color	Emission color and mask. Defaults to black.
emission_luminance	emission_luminance	Physical emission luminance in cd/m² (nits). Defaults to 100.
ao	None	Darkens creases and cavities by reducing environment lighting.

Outputs may be recognized only as maps, only as constants, or either.

Aqueduct output	Map output recognized	Constant output recognized
base_color	✓	✓
height	✓	✓
normal	✓	✓
roughness	✓	✓
metallic	✓	✓
emissive	✓	✓
emission_luminance	✕	✓
ao	✓	✓

When a recognized output is left unspecified, the in-editor material preview and Unreal material packaging use these defaults.

Aqueduct output	Default
base_color	[180/255, 180/255, 180/255]
height	0.5
normal	[0.5, 0.5, 1]
roughness	0.5
metallic	0
emissive	[0, 0, 0]
emission_luminance	100
ao	1