Directional lighting issues on meshes in large worlds (real-scale Earth orbit)

Hi everyone,

I’ve got an issue with lighting that is only present when ‘Enable large worlds’ is selected. The level comprises a real-scale orbit simulation around Earth, hence the need for large worlds. I am using a single directional light in the world to approximate the sun.

When a static mesh is located towards the centre of the world origin, lighting functions just fine. However, when placed at a great distance (say ~6,771 km for 400km low-earth orbit), at certain angles lighting bugs will flash onto the mesh’s material. This seems only present with metallic materials or those that exhibit some reflection - if I max out roughness the issue goes away. It looks like this:


This is present even if the direction light’s focus location is set to that of the mesh. I also have a LightmassImportanceVolume in place that covers the entire area. Nothing seems to change the flickering artifacts.

Is there any way to resolve this without scaling everything down to a normal world size? I’d prefer to avoid that if possible as various spacecraft models I may import can have very fine mm-level details (importing directly from CAD).

Many thanks!