This is the documentation for Enlighten.
Real-time ray tracing
Enlighten indirect lighting integrates seamlessly with Unreal Engine's real-time ray tracing features. Enlighten is enabled in ray traced effects by default, for a negligible additional shading cost in the same ballpark as static global illumination.
The images below are lit by Enlighten indirect lighting. The image on the left shows ray traced transparency OFF, while the image on the right shows ray traced transparency ON.
The same performance considerations apply as when using real time ray tracing in combination with static global illumination.
To see the effect of Enlighten indirect lighting in ray tracing, turn off the feature by setting r.Enlighten.Raytracing=0
To use Enlighten with the experimental Final Gather global illumination method, turn off Enlighten indirect lighting in the base pass by setting ShowFlag.EnlightenIndirect=0
Real time ray traced Enlighten shadows
This feature is currently experimental. To disable it, set r.Enlighten.Visibility.AllowRayTracing=0
In a project with real time ray tracing enabled, dynamic Enlighten shadows are available for a Directional Light, Point Light and Spot Light actors. Enable dynamic Enlighten shadows for the sun light source for precise sunlight bounce at any time of day.
With dynamic Enlighten shadows enabled, bright sunlight is only bounced by surfaces that are directly illuminated by the sun, not surfaces that are in shadow.
The images below are lit by Enlighten indirect lighting. The image on the left shows ray traced Enlighten shadows OFF, while the image on the right shows ray traced Enlighten shadows ON. With ray traced Enlighten shadows, green bounced light is visible where the small patch of bright sunlight illuminates the leaves of the tree.
