This is the documentation for Enlighten.
Real-world sun/sky intensity
This is an experimental option, and is currently only functional on D3D11, D3D12, PS4 and Xbox One.
In a level with a directional light with an Intensity of above 16, or a sky light with Intensity above 1000, you may notice darker-than-expected indirect lighting with Enlighten lightmaps. This is because Enlighten lightmaps in UE4 are stored with a fixed-point HDR representation.
Real-world values for sunlight may require an intensity of around 2000. In this scenario, Enlighten indirect lighting looks dark and flat.
To fix this, you can enable experimental floating-point HDR lightmaps, which:
display much greater range of values while preserving precision where it's most needed
don't require additional memory
don't significantly affect GPU or CPU overhead
To enable the floating point pixel format for the irradiance lightmap:
In your project's DefaultEngine.ini, add the line:
r.Enlighten.LightmapPixelFormat=1Restart the editor.