MIA Material BRDF

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MIA Material BRDF by Nicholas Breslow, modified by Antonio Neto

MIA Material BRDF is an implementation of the popular mia_material found in MentalRay.

It tries to mimic the results you get in your offline renderer. Limitations exist due to the lack of raytracing inside of MARI.

For a detailed description of the MIA_Material click here.






Node Overview

Node Ports

Maps the diffuse color, i.e. the main color of the material.

Maps the amount of diffuse reflections.

Maps the Oren-Nayar "rougness".

Maps overall reflectivity color. Normally white.

Maps overall reflectivity level. Multiplied by the BRDF Group parameters.

Maps reflection glossiness. 1.0 = perfect mirror.

Maps the Index of Refraction.

Maps the transparency (refraction) color.

Map the overall transparency level. Please note Transparency is a 'fake' showing more or less of the environment map.

Maps the transparency glossiness/bluriness

Anisotropy. 1.0 = Isotropic.

The rotation of the anisotropy direction.

Maps a custom (non-mari) ambient occlusion.

Normal Map

Bump Map

Maps a vector Channel. Refer to page 129 of the Mari User Guide for more information.

Displacement Channel

Node Properties


Diffuse Weight sets the desired level (and diffuse the color) of the diffuse reflectivity. Since the material is energy conserving, the actual diffuse level used depends on the reflectivity and transparency

The diffuse component uses the Oren-Nayar shading model.

When Diffuse Roughness is 0.0 this is identical to classical Lambertian shading, but with higher values the surface gets a a more "powdery" look.


The Reflectivity (together with Reflection Color Input ) define level of reflections as well as the intensity of the traditional "highlight" (also known as "specular highlight").

Reflection glossiness defines the surface "glossiness", ranging from 1.0 (a perfect mirror) to 0.0 (a diffusely reflective surface):

Skips actual reflections, and only does light highlights from point lights

Metal mode. Uses the diffuse color as reflection color.


The Index of Refraction.

The overall transparency level. Please note Transparency is a 'fake' showing more or less of the environment map

Defines how sharp or blurry the refractions/transparency are, ranging from a 1.0 (a completely clear transparency) to 0.0 (an extremely diffuse transparency)

Thin walled simulates 'solidness' for refractions (double sided) on single faces.


The parameter sets the ratio between the "width" and the "height" of the highlights, hence when anisotropy is 1.0 there is no anisotropy, i.e. the effect is disabled.

The rotation of the anisotropy direction. The values are in radian.

The value 0.0 is un-rotated, and the value 1.0 is one full revolution (i.e. 360 degrees)

The space which defines the "stretch directions" of the highlights are derived from the texture space set by the Anisotropy Channel'


With Use Fresnel Reflection on, the reflectivity on the angle is then solely guided by the materials IOR.

This is known as Fresnel reflections and is the behavior of most dielectric materials such as water, glass, etc.

With Use Fresnel Reflection off, the  0 Degree Reflection defines the reflectivity for surfaces directly facing the viewer, and 90 Degree Reflection defines the reflectivity of surfaces perpendicular to the viewer. The BRDF Curve parameter defines the falloff of this curve.

Ambient Occlusion

Used for doing more "traditional" AO, i.e. supplying the imagined "ever present ambient light" that is then attenuated by the AO effect to create shadows.

Ambient Occlusion value, only has an effect with a value other than 0.0 on Ambient slider.


Intensiry of the highlights. The default value of 1.0 is the "as close to physically correct as possible" value. This parameter allows tweaking this default value where values above 1.0 makes the highlight stronger, and below 1.0 weaker.

An additional color simply added to the other shading.


Midpoint (0 disp) of your dispacement

Intensity of your displacement

Intensity multiplier of your displacement

Quality and detail of the screen space tesselation

When on, new normals will be calculated after displacement.


Scale of your bumpmapping

Defines Accuracy vs. Performance Mode of the Bump Mapping.

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