Unreal Engine Issues
Unreal Engine Issues
Niagara mesh particles invalidate lighting when "Cast Shadow" is enabled with Hardware Ray Tracing enabled
UE - Graphics Features - Lumen - Jun 24, 2025Lumen HWRT, combined with Niagara Mesh Renderer, can cause the Lumen Scene to be reset, resulting in a sudden change to indirect lighting. ...
DiffuseIndirect_Lumen_3 parameter missing and causing crash with Screen Space reflections and Lumen Async Compute
UE - Graphics Features - Lumen - May 3, 2025When the Reflection Method is set to Screen Space and Lumen reflections async compute is enabled Unreal will crash because DiffuseIndirect_Lumen_3 parameter missing, due to how DenoiserOutputs are o ...
Divergent group barriers in Lumen
UE - Graphics Features - Lumen - Apr 23, 2025Intel reported GPU crashes on their hardware caused by divergent group barriers in ScreenProbeConvertToIrradianceCS:[numthreads(THREADGROUP_SIZE, THREADGROUP_SIZE, 1)] void ScreenProbeConvertToIrra ...
Lack of multi-bounce when using software traced lumen radiosity
UE - Graphics Features - Lumen - Apr 4, 2025Certain Lumen Hardware Ray Tracing CVars, when disabled in isolation, will not fall back to tracing the Global Distance Field, because the Global Distance Field is still disabled. The function "Lum ...
Skylighting on distant objects causes severe flickering with Lumen
UE - Graphics Features - Lumen - Mar 31, 2025Lighting 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 ...
r.Lumen.Reflections.DownsampleFactor split screen artifact
UE - Graphics Features - Lumen - Dec 6, 2024In Split-Screen, with "r.Lumen.Reflections.DownsampleFactor" set to 2, it is possible to have vertical colored artifacts on View 1 (the second view). The Licensee reported the artifact occurred on ...
Lumen temporal flicker after leaving Editor open for 3+ days
UE - Graphics Features - Lumen - Nov 18, 2024Lumen GI has temporal flickering/noise after running the Editor for 3+ days. ...
Lumen doesn't handle Area Lights Reflection Occlusion well
UE - Graphics Features - Lumen - Oct 18, 2024Ghosting effect of fast moving objects in Lumen
UE - Graphics Features - Lumen - Oct 15, 2024Lumen doesn't use correct sky light settings when GI scalability changes from Low to High
UE - Graphics Features - Lumen - Sep 24, 2024When the Global Illumination scalability settings are changed in the editor from High to Medium, they primarily act on the r.Lumen.DiffuseIndirect.Allow and r.SkyLight.RealTimeReflectionCapture. No ...