V-Ray Material Diffuse

Color – Specifies the diffuse color of the material. Note: the actual diffuse color of the surface also depends on the reflection and refraction colors.

Roughness – Specifies the roughness of the diffuse part of the material. Used to simulate rough surfaces or surfaces covered with dust (for example, skin, or the surface of the Moon). See the Diffuse Roughness example below for more information.

Roughness Model – Specifies the Roughness model.

Oren-Nayar – A reflectivity model for diffuse reflection from rough surfaces that has been shown to accurately predict the appearance of a wide range of natural surfaces. We recommend using this roughness model.
Gamma Based – The roughness model used in previous versions of V-Ray. This is not the recommended option.

Opacity – Assigns opacity to the material where 1.0 is completely opaque and 0.0 is completely transparent.

Opacity Mode – Controls how opacity is sampled.

Normal –  (Legacy) The opacity map is evaluated as normal: the surface lighting is computed and the ray is continued for the transparent effect. The opacity texture is filtered as normal.
Clip – (Very fast) The opacity texture is not filtered and it is clipped to either fully opaque or fully transparent based on the mid-point value. Useful when there are many transparent surfaces one behind the other like leaves.
Stochastic – (Optimal) The opacity texture is filtered and the surface is randomly shaded as either fully opaque or fully transparent for a correct average appearance.

Opacity Source – Chooses between Grayscale and Colored opacity.

Self-Illumination – Specifies the self-illumination color of the material.

Self-Illumination Mult. – Specifies a multiplier for the self-illumination of the material.

Self-Illumination Affects GI – When enabled, the self-illumination color affects GI computations.

Compensate Exposure – When enabled, the illumination of the self-illumination is adjusted to compensate the exposure correction from the V-Ray Physical Camera.