Standard

The standard type is a PBR-compliant material capable of creating diffuse, metallic, transparent and translucent surfaces.

Standard surface components

SURFACE COMPONENT

Generic

  • Base color: The visible color of the surface
  • Translucency: Makes the material semi-transparent and is controlled by the color or texture that is assigned to it
  • Bump: Adds texture to the material at a microscopic without distorting the surface. A normal map can also be used which gives superior results
  • Opacity: Makes the material transparent. Use a grayscale texture map to control which parts of the material are transparent. Black represents complete transparency and white complete opaqueness. The value acts as a switch between soft and hard clipping:
    • Soft clipping: Soft clipping is used when the value is equal to 0%. All gray values are used to clip the material
    • Hard clipping: Hard clipping is used for any value greater than 0%. The value acts as a threshold and selects which parts of the image are used to clip the material

Reflectance

  • Color: Controls the reflectance of the surface.
  • Roughness: Controls the roughness of the surface affecting the specular reflectance and transmittance. 0% creates a perfect mirror reflection. Increasing the value will spread and distribute reflections a create a more matte surface
  • Metallic reflections: Defines the color of the metallic part of the material
  • Metalness: Controls whether the surface is metallic or not
    • Index of refraction (n): defines how much light is bent and reflected when it comes into contact with a transparent surface. For example, air's values, 1.0, causes no distortion of background objects seen through the transparent surface
    • Extinction coefficient (k): refers to light that is likely to be lost (i.e. absorption and scattering). The higher the extinction coefficient, the more opaque the material. You can use a value of zero or above
  • Anisotropy: Stretches and blurs the highlights against the grain of the material which is particularly useful for metals
    • Rotation: Rotates the stretched and blurred highlights created by the anisotropy. Values range from 0 to 360 degrees. The greyscale values of a texture can also be used

Transmittance

  • Color: The color of transmittance. To get a perfect transmissive material, remove the base color.
  • Abbe number: Describes the variation of the index of refraction with respect to the wavelength. Can be used to create a dispersion effect which is useful for transparent surfaces (e.g. gemstones)
  • Index of refraction: Defines how much light is bent and reflected when it comes into contact with a transparent surface. For example, air's values, 1.0, causes no distortion of background objects seen through the transparent surface

Surface component

COATING COMPONENT

The coating layer uses a special reflection model with only the specular component. It is useful for simulating varnishes and paints on a layered material. The coating itself reflects some light, and the surface component absorbs the rest of the light.
You can change the extinction coefficient value to modify the reflectance (based on Fresnel equations) and define the absorption density of the surface component underneath. Both the extinction coefficient and the thickness of the material are used to calculate absorption at a microscopic level.

  • Color: The reflectance color of the coating layer
  • Roughness: Controls the coating roughness
  • Anisotropy: Stretches and blurs the highlights against the grain of the material
    • Rotation: Rotates the stretched and blurred highlights created by the anisotropy. Values range from 0 to 360 degrees. The greyscale values of a texture can also be used
  • Bump: Adds texture to the material at a microscopic without distorting the surface. A normal map can also be used which gives superior results
  • Index of refraction (n): Defines how much light is bent and reflected when it comes into contact with a transparent surface. For example, air's values, 1.0, causes no distortion of background objects seen through the transparent surface
  • Extinction coefficient (k): Refers to light that is likely to be lost (i.e. absorption and scattering). The higher the extinction coefficient, the more opaque the material. You can use a value of zero or above

Coating component

MEDIUM COMPONENT

True volumetric scattering is supported and Thea Render can solve light transport problem that includes participating media. There are a lot of possibilities since mediums can be both homogeneous and heterogeneous and a lot of supported phase functions.

  • Absorption color (1/m): Defines the transmittance color this is actually the color visualized after a distance of 1 meter (assuming unit density and no scattering). When the distance is less than 1 meter, the color shifts towards white and when the distance gets bigger the transmittance shifts towards black. The color change along to distance is strongly nonlinear and thus it is recommended to avoid highly saturated colors.
  • Scatter color (1/m): Defines the scattering color. This is the color that bounced particles (in the medium) have. The sum of absorption and scatter color (multiplied by their corresponding densities) defines the extinction coefficient of a medium which is used to calculate the total absorption at a distance. The scatter color may be applied numerous times for particles that bounce inside the medium (especially for highly scattering medium) and so, it is also recommended here to avoid highly saturated colors.
  • Phase function: A phase function defines the variation of outgoing radiance over the sphere of directions and it is the medium analog of a bi-directional scattering distribution function (which is used for surface). The available functions are: Isotropic, Rayleigh, Mie Hazy, Mie Murky, Mie Retro or Henyey Greenstein. Most used phase functions are isotropic and Henyey Greenstein.
  • Asymmetry: This parameter defines the asymmetry parameter of Henyey Greenstein phase function. This parameter is unit less and takes values from 1 (totally back scattering) to 1 (totally front scattering). A value of 0 is balanced scattering between back and forth directions and it is the same like using an isotropic phase function.

Medium component

EMITTANCE COMPONENT

Thea Render supports both area and point light emitters. The area emitters are applied to a surface (sometimes are also called mesh emitters when the surface is a mesh). Typically, the area emitter has a diffusion like emission model and it uniformly distributes light along all directions in the above hemisphere. Nevertheless, more complex emission models can be defined by making use of an IES file.

  • Emittance: Defines the emittance color
  • Power: The power of the emittance using the units defined below
  • Efficacy (lm/W): Defines the energy loss of the emitter. Maximum efficacy is 683 lm/W which corresponds to lights with no energy loss, meaning that all their power is converted to visible light
  • Passive emittance: The emittter will not cast light into the scene
  • Unit: The available units are: Lumens, lm/m2, Candelas, cd/m2, Watts, W/m2, W/sr, W/sr/m2, W/nm, W/nm/m2, W/nm/sr and W/nm/sr/m2

Emitter component