About Physical Materials Appearance

A physical material appearance is defined by specific parameters.

You can access these parameters in the Appearance Domain dialog box. The sections below give an exhaustive list of parameters for all physical materials. Depending on the material, you are using, not all these parameters are available.

This page discusses:

See Also
About Physical Materials

Base Coat

These parameters define the paint appearance and are relevant for the +Car Paint material only.

The following parameters are available.

Type Description
Base Color Defines the color of a light reflected in a broad range of directions.
Edge Color Defines the material angular color variation.
Edge Color Bias Defines the material angular color variation slope.
Lit Color Defines the color of light reflected in a single outgoing direction.
Note: Use the parameter in compliance with the Specular Weight parameter.
Lit Color IOR Defines the base coat reflectivity.
Note: Use this parameter in compliance with the other Lit parameters to define the reflectivity of lights.
Lit Color Glossiness Defines the glossy appearance of the material according to the specular reflection.

It defines the specular reflection lobe by approximating the surface glossiness.

Note: Use this parameter in compliance with the Lit Color IOR parameter to define the reflectivity of lights.

Flakes

Flakes are thin and highly reflective particles. They are often used in car paint or make-up powder.

The following parameters are available:

Parameter Description
Flakes Intensity Defines the intensity of the flakes layer.
Flakes Color Defines the flakes color.
Flakes Size Defines the size of the flakes.
Flakes Density Defines the amount of the flakes.
Flakes Glossiness Defines the general glossiness of the flakes.
Note: When this value is 0.0, the flakes behave like mirrors, which take longer to resolve during rendering. Higher values let individual flakes appear glossier.
Flakes Bumpiness Defines the distribution of the flakes orientation.
Note: Low values result in flakes that are oriented toward the surface. Higher values result in more randomly oriented flakes.
Flop Color Defines the flake angular color variation.
Flor Color Bias Defines the flake angular color variation slope.

Coating

A coating is an additional reflective transparent layer of matter that is put over another. It is often used to represent varnish.

The following parameters are available.

Parameter Description
On/Off Activates or deactivates coating.
IOR Defines the reflectivity of the coat layer.
Coating Color Defines the color passing through the coating.
Coating Glossiness Defines the glossy appearance of the coating layer.
Coating Normal Defines the surface's relief deformation through the surface normal gradient.

Color

The color defines the absorbed spectrum.

The following parameters are available.

Type Description
Diffuse Weight Defines the intensity of the diffuse reflection.
Note: This parameter is taken into account for the computed diffuse reflection only.
Diffuse Color Defines the spectrum of the diffuse illumination.

A black color deactivates the emission.

If you use a texture, the alpha is ignored.

Specular Weight Defines the intensity of the specular reflection.
Note: This parameter is taken into account for the computed diffuse reflection only.
Specular Color Defines the spectrum of the specular illumination.
Emissive Color Defines the emission spectrum.

A black color deactivates the emission.

If you use a texture, the alpha is ignored.

Volume Color Defines the absorbed spectrum.
Tip: Use this parameter in compliance with the Transparency parameter.
Recommendation: Use a texture for the Diffuse Color parameter, not for the Volume Color parameter.

Reflectance

The reflectance represents the amount of light reflected by the surface. It is the way the light behaves when it strikes the interface between two media.

The IOR (Index of Refraction) parameter defines the way the light is refracted when crossing the interface between two media.

Surface

The surface is the material represents the surface variation in height. It is the way the height interferes with the light when striking or crossing the surface. It is also used to reproduce perforations. Depending on the scale of the variation, different techniques can be used.

The following parameters are available and stand in the range [0.00-1.00].

Type Description
Diffuse Glossiness Defines the diffuse reflection lobe by approximating the surface glossiness.
Specular Glossiness Defines the specular reflection lobe by approximating the surface glossiness.
Specular Anisotropy Defines the ratio of the specular highlight deformation.
Specular Anisotropy Direction Defines the orientation of the specular highlight.
Transparency Glossiness Defines the perturbation of the transparency when light passes through the surface.
Note: This material appearance is not supported in real-time visualization mode.
  • Normal
Defines the curvature deformation of the surface with the surface normal gradient.
  • X defines the gradient of the surface tangent direction.
  • Y defines the gradient of the surface bitangent direction.
  • The Z channel is not taken into account.
  • Bump
Defines the intensity of the curvature deformation of the surface that is specified by the Normal parameter.
  • Height
Defines the surface elevation.
Note: If you connect a colored texture to it, the average of the three RGB channels is used as a scalar value.
  • Displacement
Defines the intensity of the surface elevation, specified by the Height parameter.
Note: Unlike the Height parameter, the Displacement parameter is not connected to a texture and can be interpolated to adjust the elevation effect across renderers.
  • Opacity
Defines the surface opaqueness.

If you connect a texture to it, the material appears partially transparent.

For textures in black and white, white is opaque and black is transparent.

If you connect a colored texture to it, the average of the three RGB channels is used as a scalar value.

  • Ambient Occlusion
Defines the self-shadows of a surface that can appear in holes, embosses, and any surface alteration.

Emittance

The emittance is the material appearance that represents the amount of light emitted by the surface. It is specific to simulating LED (Light-Emitting Diode), surface lights, and other types of light.

The Emissive Intensity parameter defines the intensity of the emission.

Notes:
  • The intensity of the emission depends also on the surface area on which the material is applied: the greater the surface, the more intense the emission is.
  • This material appearance is not supported in real-time visualization.

Volume

The volume represents the interaction between light and matter within your shape. For the volume appearance to be visible, define the Transparency parameter to a value greater than zero.

Four types of volume are available.

Type Description
Thin wall Gives thin walls to your glass product.
Transparency Defines the intensity of the transparency.
IOR (Index of Refraction) Defines the way in which light is refracted within the volume.

The value stands in the range [1-10].

Absorption Distance Defines the distance over which light is totally absorbed within a homogenous medium.

The value stands in the range [0.00-1e+006] millimeters.

Note: This parameter depends on:
  • the geometry where the material is applied.
  • the absorbed color that defines which spectrum is absorbed over the distance.
Abbe Number Defines the dispersion of the material light. The value stands in the range [0.00-100.00].
Scattering Distance Defines the distance at which there is a 50% probability that light is scattered.

Scattering

Defines the deviation of light rays.

The following parameters are available:

Parameter Description
Translucency Scattering Defines the perturbation of transparency when the light goes through the surface.
Subsurface Scattering Defines how light is reflected a number of times at irregular angles inside the material after it penetrates the surface. lre-t-GGX-Modify.xml