Table Of Contents
Introduction
A portal light is a rectangular area light used to assist in indoor Global Illumination. It acts a virtual window, casting direct lighting into a room from the environment outside. Portal lights effectively give you one bounce of 'brute force' Global Illumination for 'free'. If you were to just model a transparent window, you would need up to 4 times the amount of 'brute force' Global Illumination rays to achieve the same noise-free lighting, which of course would have a negative impact on performance. Portal lights blocks and absorbs Global Illumination rays. It works by sampling light color from the environment map shader, either the efault scene environment map shader, or the 'Environment Shader' parameter.
General
On
Turns the portal light on or off.
Intensity Multiplier
Specifies a multiplier for the intensity of the light cast by the portal.
Tint Color
Specifies a color with which to tint the environment samples. Tint Color only affects the color of the light cast from the portal, not the color of the portal itself when seen either directly by the camera or indirectly via reflections or refractions.
Portal Transparency
Specifies a color with which to tint the portal when seen directly through the camera or indirectly via reflections or refractions. A color of (0,0,0) will make the portal completely black, while a color of (1,1,1) will make the portal completely transparent. Colors between (0,0,0) and (1,1,1) will result in a partially transparent, tinted portal.
Samples
Specifies the number of ray samples to use for the portal light. More samples will produce smoother lighting and shadows.
Generally, the larger a portal is or the more intense the environment is (and hence the more intense the light cast by the portal is), the more samples are needed to produce noise-free results.
Ray Contribution
See Common Redshift Light Parameters.
Shadow
See Common Redshift Light Parameters.
Volume
See Common Redshift Light Parameters.
Photon
See Common Redshift Light Parameters.
Custom Environment
Environment Shader
Connect a custom environment shader here.
This will override a scene environment shader that is connected in the Redshift render settings Output tab.