Surface2¶

The Surface2 material is a general purpose material that can render a broad range of surfaces with a realistic look and offers consistent responses under different lighting conditions.

Surface is a layered shader, with the different layers present applied from top to bottom:

Surface2 layers: Dirt Spec2 Metal Spec1 Glass SSS Diffuse

Layers

Dirt

Dirt is the topmost diffuse layer. It linearly blends with all layers below, and mute them completely when set to 1.

Dirt = 0, 0.5 and 1, Dirt Color = 0.5

Spec2

Spec2 is a clear coat GGX specular layer. It blends with below layers using Fresnel factors. Use it to render effects such as a varnish, a layer of water or oil.

Spec2 = 0, 0.5 and 1

Metal

Metal is a pure GGX specular layer. It linearly blends with all layers below, and mute them completely when set to 1.

Metal = 0, 0.5 and 1, Metal Color = 1.

Spec1

Spec1 is a GGX specular layer. It blends with the below Glass/SSS/Diffuse layers using Fresnel factors.

Spec1 = 0, 0.5 and 1.

Velvet

Velvet is a flipped GGX specular layer, which simulates small details which are mostly perpendicular to the surface normal, such as micro hair.

Velvet = 0, 0.5 and 1. Diffuse Color is red, to emphasize on the velvet effect.

Glass

Glass is a GGX refraction layer, which simulates refraction in homogeneous materials, such as water, glass, ice. It linearly blends with the SSS/Diffuse layers, and mute them completely when set to 1.

Glass = 0, 0.5 and 1.

SSS

SSS is a simulated subsurface scattering layer, composed of 3 gaussian diffusion layers. Use this to simulate translucent materials such as skin, marble ... It linearly blends with the Diffuse layer.

SSS = 0, 0.5 and 1.

Diffuse

Diffuse is the lowest layer in the list.

A pure Diffuse, no other layer activated.

The Surface2 material is, for most parts, energy preserving, meaning it avoids creating/absorbing energy, and behaves consistently in all lighting conditions. Especially, the SSS and Diffuse layers are compensated with the Spec1 and Velvet layers to appear dimmer when Spec1/Velvet are brighter.

Yet, to allow for peculiar situations, some parameters can be used in a non energy preserving fashion. These uses are allowed, but can generate visible artefacts, and should be restricted to specific cases.

Other general parameters

IOR

IOR is the main Index Of Refraction control, and drives the Spec1 blending and Glass refracted direction. Higher values produce stronger speculars, and increase the refraction distortion.

IOR = 1.2, 1.5 and 2.

A Glass material with IOR = 1.2, 1.5 and 2.

Dispersion

Dispersion controls how much IOR is dependent on the wave length of light, and how much light is dispersed in the Glass layer. Spectral must be enabled to use this.

Dispersion = 0, 0.05 and 0.1.

Incandescence

Incandescence is the material self-illumination color.

Increasing colored Incandescence on a grey Diffuse.

Anisotropy Rotation

Anisotropy Rotation controls the rotation of the principal anisotropy direction.

Anisotropy Direction = 0, 0.25 and 0.5 on an anisotropic Metal.

Diffuse Parameters

Roughness

Roughness controls the roughness of the Oren-Nayar Diffuse layer. Set to 0 for a pure Lambert diffuse. Higher values produce matte materials.

Diffuse Roughess = 0, 0.5 and 1.

Color

The color of the Diffuse layer.

Various Diffuse Color settings, from white to light red.

Translucence Color

The color of the Translucent layer (as an opposite diffuse.) Translucence is useful to simulate thin objects, such as a sheet of paper, curtains or tree leaves. Note that translucence requires that the actual geometry is a single face. Thick objects should fallback on SSS instead.

Various Diffuse Color and Translucence Color, 0.75/0.25, 0.5/0.5 and 0.25/0.75.

Diffuse Color and Translucence Color mixing is not energy preserving by default. Make sure that the sum of them is not above 1 to keep the material energy preserving.

Cell Sharpness

Diffuse Cell Sharpness sharpens the penumbra area of the diffuse, to render cell-like diffuse.

Diffuse Cell Sharpness 0, 0.5 and 0.75.

Cell Center

Diffuse Cell Center displaces the penumbra area of the diffuse towards the front of the light.

Diffuse Cell Center 0, 0.33 and 0.66.

Velvet Parameters

Roughness

Velvet Roughness controls the roughness of the Velvet layer. Smaller values produce sharper highlights at grazing angles, while higher values produces smoother diffuse effect.

Velvet Roughess = 0.2, 0.5 and 1.

Color

The color of the Velvet layer.

Velvet Color from white to blue.

IOR

Velvet IOR controls, along with Velvet the strength of the Velvet layer. High values produce stronger highlights.

Velvet IOR = 2, 5 and 8.

Spec1 Parameters

Roughness

Spec1 Roughness controls the roughness of the Spec1 layer. Smaller values produce sharper, stronger highlights, while higher values produce diffuse, dimmer highlights.

Spec1 Roughess = 0.1, 0.3 and 0.5.

Color

The color of the Spec1 layer.

Spec1 Color from white to red.

Decreasing Spec1 Color to attenuate the effect of specular will leading to loss of energy. Use the Spec1 and/or Spec1 Roughness instead.

Anisotropy

Spec1 Anisotropy controls the prefered orientation of the specular highlight. 0.5 is neutral, and other values stretch the highlight in a direction or its perpendicular.

Spec1 Anisotropy = 0.5, 0.75 and 0.95.

Spec1 Anisotropy value close to 0 and 1 are more difficult to render, and may increase the rendering noise.

Metal Parameters

Roughness

Metal Roughness controls the roughness of the Metal layer. Smaller values produce sharper, stronger highlights, while higher values produce diffuse, dimmer highlights.

Metal Roughess = 0.1, 0.3 and 0.5.

Color

The color of the Metal layer.

Metal Color from white to goldish.

Profile

Alternatively, you can use a measured metal profile from the RefractiveIndex.INFO database.

Metal Profile = 'Lithium', 'Copper' and 'Gold'.

Anisotropy

Metal Anisotropy controls the prefered orientation of the specular highlight. 0.5 is neutral, and other values stretch the highlight in a direction or its perpendicular.

Metal Anisotropy = 0.5, 0.75 and 0.95.

Metal Anisotropy value close to 0 and 1 are more difficult to render, and may increase the rendering noise.

Iridescence

Metal Iridescence simulates interference fringes on the metal layer, as would a thin slab of oil on metal. 0 disables iridescence, higher values produce stronger iridescence.

Metal Iridescence = 0, 0.25 and 0.5.

Iridescence Wave

Metal Iridescence Wave controls the frequency of the iridescence. Higher values produces higher frequencies.

Metal Iridescence Wave = 2.5, 5 and 7.5.

Multiple Scattering

At higher roughness, the GGX specular model shows visible loss of energy, this is particularly noticeable on metals. Metal Multiple Scattering simulates the internal reflections to account for this loss of energy.

Metal Multiple Scattering disabled and enabled, for Roughness = 0.3, 0.6 and 0.9.

Multiple Scattering produces more noise, which leads to higher rendering time.

Spec2 Parameters

Roughness

Spec2 Roughness controls the roughness of the Spec2 layer. Smaller values produce sharper, stronger highlights, while higher values produce diffuse, dimmer highlights.

Spec2 Roughess = 0.1, 0.3 and 0.5.

Color

The color of the Spec2 layer.

Spec2 Color from white to red.

Decreasing Spec2 Color to attenuate the effect of specular will leading to loss of energy. Use the Spec2 and/or Spec2 Roughness instead.

Anisotropy

Spec2 Anisotropy controls the prefered orientation of the specular highlight. 0.5 is neutral, and other values stretch the highlight in a direction or its perpendicular.

Spec2 Anisotropy = 0.5, 0.75 and 0.95.

Spec2 Anisotropy value close to 0 and 1 are more difficult to render, and may increase the rendering noise.

IOR

Spec2 IOR controls the Spec2 layer Index Of Refraction. Higher values produce stronger speculars, and attenuate the underlying layers.

IOR = 1.3, 1.7 and 2.1.

Absorption Color

Spec2 Absorption Color simulates the absorption color of the clear coat layer. This color affects the appearance of underlying layers, not the color of the Spec2 itself, which uses Spec2 Color. Pure white disables absorption.

Various Spec2 Absorption Color settings.

The Spec2 layer can be used over different types of layers, as shown in the following examples:

Spec2 over white Diffuse+Spec1, Metal and Glass

Thickness

Spec2 Thickness controls the thickness or the density of the absorbing coating. Increasing this results in darker, more saturated rendering.

Spec2 Thickness = 0.3, 0.7 and 1.1.

Dirt Parameters

Roughness

Dirt Roughness controls the roughness of the Oren-Nayar Dirt layer. Set to 0 for a pure Lambert diffuse. Higher values produce matte materials.

Dirt Roughess = 0, 0.5 and 1.

Color

The color of the Dirt layer.

Various Dirt Color settings, from white to light brown.

SSS Parameters

Use Diffuse Color

SSS Use Diffuse Color blends the actual SSS color between the Diffuse Color and the SSS Color.

SSS Use Diffuse Color = 1, 0.5 and 0, with Diffuse Color pink and SSS Color blue/pink.

Width

SSS Width controls the scattering distance of the SSS layer.

SSS Width = 0.1, 0.2 and 0.5.

The SSS Width is expressed in world space.

Layer 1 Color

SSS Layer 1 Color controls the color of the first SSS lobe.

The first SSS layer, with various SSS Layer 1 Width

Layer 1 Width

SSS Layer 1 Width controls the relative width of the first SSS lobe. Scaling the global SSS Width will also scale the different SSS lobes.

The first SSS layer, with various SSS Layer 1 Width

All three SSS lobes are purely additive, and the explanation concerning the first layer are the same for the other lobes.

Front Scattering

SSS Front Scattering multiplies the lighting of front facing lights.

SSS Front Scattering = 0.5, 1 and 1.5.

Values different from 1 are not energy preserving, and should be used carefully.

Back Scattering

SSS Back Scattering multiplies the lighting of back facing lights.

SSS Back Scattering = 0.5, 1 and 1.5.

Values different from 1 are not energy preserving, and should be used carefully.

Blur

SSS Blur controls the blurring of the Diffuse/SSS color between the light entry point and the light exit point. 0 does not blur the texture, 0.5 blurs equivalently between the entry and exit point, while 1 fully blurs.

SSS Blue = 0, 0.5 and 1.

Glass Parameters

Roughness

Glass Roughness controls the roughness of the Glass layer. Set to 0 for a perfectly smooth glass. Higher values produce a frosted glass appearance.

Glass Roughess = 0, 0.15 and 0.3.

Color

Glass Color controls the color of refracted light. Note that this color is not dependent of the distance the light travels inside the glass object. To color the light through the glass, use the Absorption volume shader instead.

Various Glass Color settings, from white to pink.

IOR

When Glass IOR is left to 0, the global IOR parameter controls the refraction direction. Yet, it is possible to control the refraction independently when using a value different from 0.

Glass IOR = 1.3, 1.5 and 1.8, with IOR = 1.5.

Using a different IOR for the specular and refraction can lead to noticeable loss of energy. It is advised to use the Glass IOR carefully.

Mode

Glass Mode controls the type of glass to render. 'Double Sided' is a thick object, such a glass ball or a puddle of water. 'Thin Glass' is a thin object where the refraction change of direction is negligeable, such as a flat window or a light bulb. 'Transparent Glass' is also a thin object, but specifically rendered using opacity. Note that the Glass Roughness is not possible using 'Transparent Glass'.

Glass Mode = 'Double Sided', 'Thin Glass', 'Transparent Glass' using Glass Roughness = 0.2.

Opacity Parameters

Mask

Opacity Mask controls the global opacity of the surface. 1 is fully opaque, and 0 is fully transparent. Inbetween values produces semi transparent surface.

Opacity Mask = 1, 0.6 and 0.2.