After upgrading a Cesium project with volumetric clouds from Unreal Engine 4.27 to 5.1,
we noticed an issue where the terrain lights up brightly when the solar time is at dusk or dawn.
Below are two screenshots of a minimalistic project (Cesium Quick Start with volumetric clouds and “Use Per Sample Atmospheric Light Transmittance” enabled on the cloud component) in UE4.27 and UE5.1:
I’ve tried toggling all the possibly relevant options on the following components:
- Volumetric Clouds:
- unchecking “Use Per Sample Atmospheric Light Transmittance” fixes the lighting on the terrain, but the lighting on the clouds still looks wrong
- Cesium Georeference: clicking “Place Georeference Origin Here” seems to solve the issue, but this wasn’t necessary in UE4.
- Cesium SunSky (Directional Light, Sky Light, Sky Atmosphere): no effect
- Changing exposure and auto-exposure settings: no effect
Any help would be appreciated.