Emittance Tab

Thea Render supports both area and point light emitters. The area emitters are applied to a surface. 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.

Color: User can define the color of the light with the following options: Color, Temperature, Bitmap and Procedural.
Power: Defines the power of the emittance.
Efficacy: Maximum efficacy is 683lm/w which corresponds to lights with no energy loss, meaning that all their power is converted to visible light.
Passive Emitter: The emitter will not cast light into the scene but one will still be able to see the area emitter "lit".
IES Emitter: To convert a Standard Emitter to IES, click on the "hamburger" icon and select IES Emitter.
Multiplier: Defines the intensity multiplier for the IES file currently loaded.
Custom Light Evaluation: Custom Light Evaluation allows the user to select which components (such as Diffuse, Translucent, Reflectance, Transmittance, and SSS) will be evaluated for a given material and light, thus removing unwanted contributions and accelerating render times.