This is the documentation for Enlighten.

From static to dynamic lighting

Owned by William Joseph
Dec 22, 2020

Before you set up your existing level to use dynamic Enlighten lighting, we recommend you remove any Lightmass lighting. Using Lightmass direct lighting (from static lights) and Enlighten indirect lighting together can cause problems. Removing Lightmass also avoids confusion, as Enlighten and Lightmass lighting can look similar, and makes it easier to fix problems, because you can rule out Lightmass as the cause.

  • Enlighten provides indirect lighting for Stationary lights and Movable lights.
  • Lightmass provides lighting for lighting for Stationary lights (as shadow maps) and Static lights.

Remove Lightmass lighting

To remove Lightmass lighting:

  1. Under Details > Transform, make sure the Mobility for each light is set to Movable.
  2. In World Settings > Lightmass Settings, click the yellow arrow to reset all the settings to the default.
  3. Run Build > Build Lighting Only to rebuild the lighting.

    The Lightmass build should complete quickly.

If UnrealLightmass.exe is missing, the lighting build fails and the editor reports an error. This happens if you didn't compile UnrealLightmass.exe when you installed Enlighten UE4.

Verify that your level only uses Enlighten indirect lighting

To hide and show Enlighten indirect lighting, toggle Show > Lighting Features > Enlighten Indirect Lighting.

If your level uses only Enlighten indirect lighting, you should now see only the direct lighting. To hide and show the direct lighting, toggle Show > Lighting Components > Direct Lighting.

Minimize dynamic shadow cost

Enlighten leaves the computation of direct lighting and shadows to the UE4 renderer. For a Movable light, the cost of UE4 dynamic shadows can be significantly higher than for static shadows.

The cost of UE4 dynamic shadows varies with the configuration of meshes and lights in the level. If you find that the cost is excessive for your level, try one or more of the following approaches to reduce the cost:

  • For point and spot lights that move, turn off shadows or use Shadow Map Caching (UE4 documentation).
  • Movable directional lights cast shadows for the whole level and therefore incur the most cost. Where possible, disable shadowcasting per actor.
  • Depending on the level, general optimization techniques such as merging actors (UE4 documentation) can significantly reduce the cost of shadows.
  • For lights that don’t move, set the lighting mode to Stationary and bake only the shadows using Lightmass.

Each of the above optimizations requires additional artist time to configure the level. We recommend that you apply each optimization only if you have problems with the cost of dynamic shadows.