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Note

In the parameters below, some of them can be overridden by a PxrLayer when connected to the Input Material or through a PxrLayerMixer. PxrLayerSurface is designed to better illustrate which parameters are not able to be overridden in a layer by including only parameters that are global. We recommend this material when you know you will be layering. The results of these settings are unchanged.

  • Bold Face parameters are layerable, able to be overridden per layer.
  • Italicized parameters are not able to be layered or overridden. These are globally obeyed for all layers. For example: Choosing GGX as a specular model will mean all layers will be GGX for that parameter.

 

 

 

Expand
titleDiffuse Parameters

Diffuse Parameters

The diffuse parameters control the look of basic diffuse reflection. These are often used to define primary color attributes for opaque objects; wood textures, label text, polka dots, or more, you can find them all connected here. This lobe is on by default.

Gain

Gain is the weight applied to the diffuse parameters. You may also drive this with another pattern to show things like fading or wetness (where liquid darkens a surface). Below are examples at 0.0, 0.5, and 1.0 gain for a 50% grey material.




Color

Color is typically where textures or patterns are connected to create color for opaque objects. This is where a wood color texture would go, for example.




Roughness

Diffuse roughness is how you would simulate a powdery surface like dried clay or dust.

 

 

Bump

Bump mapping is a great way to fake the appearance of physical detail using shading instead. If this is not set, it will use the global bump normal specified in the Properties section near the bottom of this page.

 

 

Double Sided

If on, illuminate both sides of the surface for this diffuse lobe, that is, this will illuminate the surface whose normal is pointing away from the camera (2-dimensional objects) as well.

 

Use Diffuse Color

This only applies when Double Sided is on. By default, this is on to use the Diffuse Color for the back color.

 

Back Color

This only applies when Double Sided is on. When Use Diffuse Color if off, this sets the back color (the color for the back side). By default, it uses the Diffuse Color.

 

Transmit Gain

This only applies when Double Sided is on. This sets the transmit gain as a multiplier. If it's 0.0 then the effect is off.

 

Transmit Color

This only applies when Double Sided is on. This sets the transmit color which could be different than the diffuse or back color. This is ignored if Transmit Gain is zero. This effect is useful for thin objects like leaves or paper. Below there's a light placed in the interior of the object and some interior text can be seen as light transmits through the surface.

 

 

Expand
titleSpecular Parameters

Specular and Rough Specular Parameters

The specular parameters control specular reflection. This is where you might define how shiny or reflective an object is. Is it plastic, a polished marble table, or  is it a mirror? The Rough Specular lobe below this has identical settings and effects.

Note

There's also the option for Artistic and Physical controls. The Artistic controls allows you to manually alter the properties of the reflection to match your tastes. Using Physical (with provided presets) can provide you with a matching real-world response for those looking to duplicate reality without endless tweaking.

 

Specular Model

Select which specular model to use: Beckmann or Ggx. Ggx may be preferred for its "tail", or how the highlight has a soft fade from the center reflection of a lightsource. Left is Beckmann and Right is GGX with roughness 0.25.

 

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Specular Fresnel Mode

In Artistic mode, specular fresnel response will be controlled by its Face Color, Edge Color, and Fresnel Exponent.

In Physical mode, specular fresnel response will be controlled by its Refractive Index, Extinction Coefficient, and Edge Color.


Face Color (Artistic Mode)

Specular color at facing angle (0 degree incidence). Note that there is no separate gain control. To control the specular "gain", simply adjust the color value or connect it to a PxrExposure node. Below are different choices including textured at roughness 0.25.

 

 

Edge Color

Specular color at the glancing angle (90 degree incidence). To control the edge specular "gain", simply adjust the color value or connect it to a PxrExposure node. Below are different choices including textured at roughness 0.25. The Fresnel Exponent is also reduced here to make it more obvious.

Note

Understand that this control changes meaning in the Physical Mode and operates as a multiplier for the reflection result in Physical mode. You can control reflection intensity and even tint the result using this parameter in Physical Mode.


 

 

Fresnel Exponent (Artistic Mode)

Specular fresnel curve exponent. Lower numbers reduces the effect of Face Color while increasing the effect of Edge Color. Higher numbers reverse this. If your face and edge colors are the same, then there is no visible effect. Below we use a red Face Color and green Edge Color and increase the Fresnel Exponent from 0.1 to 1.5 and finally 5.0 with a small roughness.

 

 

Refractive Index (Physical Mode)

This is a parameter meant to describe a physical refractive Index; the dielectric index of refraction for the material. Channel values for this parameter typically lie in the range 1 - 3. Since we support 3 color values to capture the spectral effect presets may be preferred over color pickers to avoid lots of tweaking.

 

Extinction Coefficient (Physical Mode)

Extinction Coefficient is a second refractive index for the material useful for characterizing metallic behaviors. Channel values for this parameter typically lie in the range 1 - 3. Since we support 3 color values to capture the spectral effect presets may be preferred over color pickers. When 0, the material reacts as a dielectric (glass, clearcoat). When non-zero, the material responds as a conductor would. Since this is based on physical values you should the presets more helpful than manual tweaking of settings.


Roughness

Specular roughness. A greater value produces rougher or "blurry" specular reflection. At 1.0 it resembles a diffuse surface and at 0.0 it's a perfectly clear reflection. Most objects will be realistic somewhere in between these values. Texturing this value may give you interesting effects like smudges, greasy fingerprints, and worn surfaces. Below are examples from 0.0 to 0.5 and finally 1.0 (diffuse).

 

 

Anisotropy

Controls the shape of the specular highlights and reflections. 0 means isotropic which produces the regular circular specular highlight. Values from -1.0 to 1.0 produce the range of ellipses (stretching) from wide to tall.

By default, the direction of anisotropy is controlled by the model texture parameters. If the Shading Tangent is specified, it is used instead. Below are examples of -1.0, 0.0, and 1.0.

 

 

Shading Tangent

Controls the anisotropy direction. Only valid when it is connected to a pattern. This is useful for making brushed metals. Below are three examples using textures and an Anisotropy of -10

 

 

Bump

Normal to use for the specular illumination. If this is not set, it will use the global bump normal specified in the Properties near the bottom of this page.

 

 

Double Sided

If on, illuminate on both sides of the surface for this specular lobe, that is, this will illuminate the surface whose normal is pointing away from the camera as well.

 

 

Rough Specular

Identical Specular parameters except it has a larger default roughness which is 0.6. This layer is intended for use with higher roughness settings than the Specular lobe above. Below from left to right: Rough Specular, Specular, both lobes combined.

 

 

 

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