The Transmission material is special material simulating transmissive surfaces. The material can emit refractive caustics and allows you to choose between different BRDFs using the Brdf attribute. It should be blended with a diffuse and reflective materials since it lacks a diffuse/reflection component.
The color of the material is the color of the light path when it exits the surface after it has been transmitted from the material. The direction of the transmitted light path is directly dependent of the Index of Refraction (IOR) attribute.
|Color||Define the color of the transmission.|
|Gain||Set the gain of the transmission color.|
|Exit Color||Define the color returned by the path tracer when the path has reached the maximum refraction depth set in the path tracer. This is useful is some complex rendering scenarios such as when rendering a crystal like materials.|
|Index of Refraction||Define the index of refraction of the surface.|
Index of Refraction#
The material supports Roughness, Anisotropy and multiple microfacet models that can be selected using the Btdf attribute.
|GGX||GGX distribution results are very close to empirical data.|
|Beckmann||Beckmann distribution tends to provide sharper reflections when compared to GGX|
Anisotropy control how much the specular highlight is stretched along a direction defined by Anisotropy Space.
- When set to Tangent UV the material uses a frame defined by the UV mapping of the texture connected to the Anisotropy Direction, Anisotropy Rotation, Anisotropy, Roughness or Color attributes.
- When set to Tangent Parametric the material uses the surface parametric frame whereas in Object it uses the frame defined by the object. Anisotropy Direction defines the direction of the anisotropy on the local surface frame and Anisotropy Rotation defines the rotation of the anisotropy along the direction.
The material below has its Roughness set to 100%
The Transmittance simulates the density of the dielectric medium filtering the color of ray the further it travels through the material. Transmittance Color defines the reflected color of the medium while Transmittance Density controls the density of the medium which directly translates into the scale factor of the ray attenuation. The higher the value, the more the color of the ray shifts towards the color defined by Transmittance Color.
The material below has a Transmittance Color set to (0.2, 0.6, 0.2)
The Transmission Scattering simulates the scattering of light inside the medium turning it as a homogenous volume. The maximum number of bounces of the scattering within the volume is controlled by Volume Depth attribute.
Note that transmission scattering doesn't render properly when the camera is placed inside the medium.