MIA Material BRDF by Nicholas Breslow, modified by Antonio Neto


  • Where to find it:


    • Shader Palette / Add New Shader


    • NodeGraph / Right Mouse Click / Nodes / Shader Network / Standalone




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.



Samples



GLASS



BRUSHED METAL





GOLD







PLASTIC








Node Overview



Node Ports


  • Diffuse Color

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


  • Diffuse Weight

Maps the amount of diffuse reflections.


  • Diffuse Roughness

Maps the Oren-Nayar "rougness".


  • Reflection Color

Maps overall reflectivity color. Normally white.


  • Reflectivity

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


  • Reflection Glossiness

Maps reflection glossiness. 1.0 = perfect mirror.


  • Index of Refraction

Maps the Index of Refraction.


  • Refraction Color

Maps the transparency (refraction) color.


  • Transparency

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


  • Refraction Glossiness

Maps the transparency glossiness/bluriness


  • Anisotropy

Anisotropy. 1.0 = Isotropic.


  • Anisotropy Rotation

The rotation of the anisotropy direction.


  • Ambient Occlusion

Maps a custom (non-mari) ambient occlusion.


  • Normal

Normal Map


  • Bump

Bump Map


  • Vector

Maps a vector Channel. Refer to Mari Online Help for more information


  • Displacement

Displacement Channel



Node Properties


Diffuse


  • Diffuse Weight

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


  • Diffuse Roughness

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.


Reflection


  • Reflectivity

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

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


  • Highlights only

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


  • Metal Material

Metal mode. Uses the diffuse color as reflection color.


Refraction


  • Index of Refraction

The Index of Refraction.


  • Transparency

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


  • Refraction Glossiness

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

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


Anisotropy


  • Anisotropy

 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.


  • Anisotropy Rotation

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)


  • Anisotropy Channel

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


    • -1: the base rotation follows the local object coordinate system.
    • -2: the base rotation follows the bump basis vectors


BRDF


  • Use Fresnel Reflection

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.


  • 0 Degree Reflection  / 90 Degree Reflection / BRDF Curve

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


  • Ambient

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

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


Advanced


  • Specular Balance

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.


  • Additional Color

An additional color simply added to the other shading.



Displacement


  • Displacement Bias

Midpoint (0 disp) of your dispacement


  • Displacement Scale

Intensity of your displacement


  • Displacement Range

Intensity multiplier of your displacement


  • Max Tesselation

Quality and detail of the screen space tesselation


  • Perturb Normals

When on, new normals will be calculated after displacement.


Bump


  • Bump Weight

Scale of your bumpmapping


  • Bump Mode

Defines Accuracy vs. Performance Mode of the Bump Mapping.




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