Unreal Engine Issues

Lumen Translucency lighting vs opaque mismatch is larger than expected

The licensee's VFX team has been struggling with getting their Niagara systems with translucent materials to fit into the environments they are being used in. In a project with default settings, the ...

Lumen Card Sharing is active on material with custom primitive data

The wrong emissive value may be used on Nanite objects with custom primitive data when Lumen card sharing is enabled. This issue can be mitigated with: r.LumenScene.SurfaceCache.AllowCardSharing 0 ...

Crash when displaying lumencards on map with many objects

There is a thread conflict between FRDGBuilder execution in Background Worker and LumenVisualizer's LumenCard add/delete process. When lumen cards are displayed in a scene with many objects, a crash ...

Niagara mesh particles invalidate lighting when "Cast Shadow" is enabled with Hardware Ray Tracing enabled

Lumen HWRT, combined with Niagara Mesh Renderer, can cause the Lumen Scene to be reset, resulting in a sudden change to indirect lighting. ...

Skylighting on distant objects causes severe flickering with Lumen

Lighting on distant meshes flickers when using Lumen and Skylights. Turning Lumen off and lighting from the skylight is stable. Turning off Lumen screen traces also lowers the amount of flickering ...

Ghosting effect of fast moving objects in Lumen

Lumen interior light leaking occurs with realistic sun Lux values (20k)

When a realistic sun Lux value of 20,000 for the sun directional light, interior light leaking is much more pronounced then when using the default directional light Lux value of 10 Lux. ...

Lumen reflection distortion

Lumen reflections appear distorted depending on the camera orientation. ...

Masked TwoSided material causing lumen direct lighting to leak through walls

It appears that LumenScene's Hardware Ray Tracing is causing light leaking into a sealed room (which should be perfectly black). This bug does not appear to happen on AMD GPUs. ...

Lumen indirect lighting artifacts when far from world origin

Lumen seems to not be using Large World Coordinates somewhere. The Lumen Scene develops artifacts at large distances (5000 KM) from the world origin. ...