Octane Standalone Documentation

The Universal Material is designed to encompass all the characteristics of the other Octane base materials (Diffuse, Glossy, Specular) into one uber-shader and to adhere to the PBR model workflow. It works well with texture maps generated using texturing tools such as Adobe ®Substance Painter with clearly defined parameters for albedo, metallic, specular, and roughness texture maps Furthermore, this material blends between dielectric and metallic using a single parameter (figure 1). 

Figure 1: Example of Metallic parameter set to 1 and 0

The Universal Material can also produce physically accurate metal types using the Refractive Index (n)  and Extinction Coefficient (k) as actual index values (figure 2). See the IOR section below. 

Figure 2: Placing real-world IOR values of Metallic objects as part of the IOR metallic input channels (Red, Green and Blue)

Universal Material Parameters

Transmission Layer

Transmission - Controls the light passing the surface of the material (via refraction).

Transmission Type - Determines how light refracts. 

• Specular - Behaves the same as transmission of the specular material, taking IOR and roughness into account. 
• Diffuse - Behaves the same as transmission of the diffuse material, not taking IOR into account and roughness has the same meaning as the in the diffuse material. If additional layers are used, the layer ordering is dependent on the side the incident rays comes from. 
• Thin Wall - Behaves the same as mode Specular but with no refraction and no roughness for transmission. 
• Thin Wall (Diffuse) - Behaves the same as mode Diffuse with the exception that the layer ordering is independent of which side the incident ray comes from. Could be used with a coating layer for foliages and leaves. 

Base Layer

Albedo - The material's base color equivalent to diffuse, with no shading, light direction, or ambient occlusion.

Diffuse BRDF Model - Provides three models for diffuse light reflectance. Lambertian reflects light equally in all directions and does not support roughness. The Octane option creates a sheen effect much like velvet. And, the Oren-Nayar option behaves more like clay. More details can be found in the BRDF Models topic. 

Metallic - The material's metallic appearance. Blends between dielectric and metallic material.

Metallic Edge Tint - The color of the edges of the metal material, only used with Artistic and IOR+Color modes.

Specular Layer

Specular - Determines the color of glossy reflections. If the Index Of Reflection is set to a value less than 0, the color's brightness adjusts to match with the Fresnel equations. This parameter has no effect when the Metallic parameter is set to 1.

BSDF Model - Determines how light is reflected from the surface. More details can be found in the BRDF Models topic.

Roughness

Roughness - Roughness values for the Specular reflection and Transmission channel.

Anisotropy - Anisotropy values for the Specular and Transmission materials. -1 is horizontal, while 1 is vertical. A value of 0 is Isotropic.

Rotation - Rotation values for the Anisotropic Specular reflection and Transmission channel.

Spread - Determines the tail spread of the specular BSDF.

IOR

Dielectric IOR - The Index Of Refraction controlling the Fresnel effect for transmission and specular reflection on dielectric materials. If the Metallic parameter is set to 1, this parameter has no effect.

Metallic Reflection Mode - This changes how OctaneRender® calculates reflectivity.

• Artistic - Uses the Specular color. The values entered into the IOR have no impact. It is simple and ideal for non-realistic results.
• IOR + Color - Uses n and k IOR values as Index of Refraction along with the Specular Color. 
• RGB IOR - The most accurate IOR mode. Uses the three IOR values; red (650nm), green (550nm), and blue (450 nm) and ignores the Specular color. Refractive Index (n)  and Extinction Coefficient (k) are actual index values. For these values go to refractiveindex and enter real IOR values according to material selected. Use the numeric field for n on the left and k on the right for each of the IOR (Red but not labled Red), IOR (Green), and IOR (Blue) parameters listed below.

Index Of Refraction - Complex-valued IOR (n-k*i) controlling the specular reflection's Fresnel effect, where n = the refractive index and k = the attenuation or extinction coefficient. For RGB mode, the IOR for red light (650nm).

Index Of Refraction (Green) - For RGB mode, the IOR for green light (550nm).

Index Of Refraction (Blue) - For RGB mode, the IOR for blue light (450nm).

Allow Caustics - If enabled, the photon tracing kernel will create caustics for light reflecting or transmitting through the object.

Coating Layer

Coating - The material's coating color.

Coating Roughness - The coating layer's roughness.

Coating IOR -The coating layer's IOR.

Coating Bump - The coating layer's Bump map. If you don't specify a Bump map, the coating layer uses the default shading normal. Otherwise, it applies the bump-mapped surface to the coating layer.

Coating Normal - The coating layer's Normal map. If you don't specify a Normal map, the coating layer uses the default shading normal. Otherwise, it applies the normal-mapped surface to the coating layer.

Thin Film Layer

Film Width - The film coating's thickness.

Film IOR - The film coating's IOR.

Sheen Layer

Sheen - The material's sheen color.

Sheen Roughness - The Sheen channel's roughness.

Sheen Bump - The sheen layer's Bump map. If you don't specify a Bump map, the sheen layer uses the default shading normal. Otherwise, it applies the bump-mapped surface to the sheen layer.

Sheen Normal - The sheen layer's Normal map. If you don't specify a Normal map, the sheen layer uses the default shading normal. Otherwise, it applies the normal-mapped surface to the sheen layer.

Transmission Properties

Dispersion Coefficient - This is the B parameter of the Cauchy dispersion model, where normal dispersion is derived through the relationship between the Index Of Refraction and the wavelength of light passing through transparent materials.

Dispersion Mode - Determines how the IOR and dispersion coefficients are interpreted. 

• Abbe Number - Measures a transparent material's dispersion. A higher value indicating less dispersion and clearer color perception. 
• Cauchy Formula - Calculates the refractive index of an optical material at any specific wavelength within the visible spectrum. 

Medium- OctaneRender® has three types of mediums to create translucent surfaces:

• Absorption Medium - Produces the appearance of a material that absorbs light while passing through a surface. The resulting color depends on the distance that light travels through the material.
• Random Walk - A newer variant of subsurface scattering that utilizes a stochastic or random process for the scattering of light through an object. This provides the most realistic result when rendering scatter volumes.
• Scattering Medium - Similar to the Absorption medium, but with an additional option for simulating subsurface scattering. Subsurface scattering is the phenomena that gives human skin and similar organic surfaces their characteristic glow under certain lighting conditions. It's a major component for creating the look of realistic skin.
• Standard Volume - Provides volume medium options with comprehensive controls for adjusting volume, scatter, transparency, emission, and temperature parameters based on imported VBD grid data. It is not meant to be used as a medium for materials, instead it is typically used with an imported VDB file.
• Volume Medium - Designed to add color and other volumetric qualities to transmissive objects. This node works best with VDB files but can also be connected to material medium inputs.

Opacity - Controls the Material's transparency with a Greyscale texture.

Fake Shadows - If enabled, light traces through the Material during the shadow calculation, ignoring refraction.

Affect Alpha - If enabled, this allows the Universal material's refractions to affect the Alpha Channel.

Geometric Properties

Bump - Simulates a relief using a Greyscale texture interpreted as a Height map.

Bump Height - Determines the height represented by a normalized value of 1.0 in the bump texture. A vaule of 0 disables the bump map and a negative value will invert the bump map.

Normal - Distorts normals using an RGB image.

Displacement - Accepts Displacement maps, allowing you to create very detailed geometry with a low memory footprint.

Smooth - If disabled, normal interpolation is disabled and triangle meshes appear faceted.

Smooth Shadow Terminator - If enabled, self-intersecting shadows are smoothed according to the polygon's curvature.

Round Edges - Rounds the geometry edges by using a shading effect instead of creating additional geometry. See the Round Edges topic in this manual for more information.

Priority - Used to resolve the ambiguity in overlapping surfaces, the surface priority control allows artists to control the order of preference for surfaces. A higher number suggests a higher priority for the surface material, which means it is preferred over a lower priority surface material if a ray enters a higher priority surface and then intersects a lower priority surface while inside the higher priority surface medium.

Emission - Also known as a Mesh emitter, this creates a surface that emits light. To activate an emission, connect the Emission input of the Diffuse material to either a Blackbody or a Texture emission map. The Textures and the Mesh Emitters (under Lighting Overview) topics in this manual cover maps in more detail.

Shadow Catcher - Makes the material a shadow catcher. The material becomes transparent unless there is some direct shadow cast onto the material, which makes it less transparent, depending on the shadow strength.

Custom AOV - Writes a mask to the specified custom AOV.

Custom AOV Channel - Determines whether the custom AOV is written to a specific color channel (R, G, or B) or to all the color channels.

Material Layer - Adds a material layer above the base layer. See the Material Layers topic in this manual for more details.