Real-world sun/sky intensity

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:

1. In your project's DefaultEngine.ini, add the line:

    r.Enlighten.LightmapPixelFormat=1

2. Restart the editor.