Material Passes

Material Passes can be accessed from the Render Toolbar > Render PassesRender passes allow a rendered frame to be further broken down beyond the capabilities of Render Layers. Render Passes vary among render engines but typically they allow an image to be separated into its fundamental visual components such as diffuse, ambient, specular, etc.. button > Info Passes tab.

The following Material Passes are available:

Opacity - Assigns a color to the camera ray's hit point proportional to the opacity of the geometry.
Roughness - Material roughness at the camera ray's hit point.
Index Of Refraction - Material index of refraction at the camera ray's hit point.
DiffuseAmount of diffusion, or the reflection of light photons at different angles from an uneven or granular surface. Used for dull, non-reflecting materials or mesh emitters. Filter - The diffuse texture color of the diffuse and glossy material.
Reflection Filter - The reflection texture color of the specular and glossy material.
Refraction Filter - The refraction texture color of the specular material.
TransmissionA surface characteristic that determines if light may pass through a surface volume. Filter - The transmission texture color of the diffuse material.