Upstreaming GPU Lightmass fork by Yujiang Wang

Development Rendering
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Hello, this project progresses work on GPU Lightmass https://github.com/AlanIWBFT/UnrealEngine/commits/gpulm\-no\-luoshuang/

From my testing and changes review it fixes problems in many areas:

  • implements baked ambient occlusion
  • adds better denoising
  • better seam prevention
  • fixes for landscape
  • fixes for ISM
  • spline meshes support
  • perf improvements

Are there any plans to upstream those changes? GPU lightmass doesn’t work for our maps without them

From this post Epic's GPUlightmass - #666 by Jimbohalo10 this is by someone who worked on it before

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hey Vasily,

As you know Yujiang, previous owner of GPU lightmass, left Epic and since then GPULM only received basic maintenance support. We merged some of the changes from his branch to get GPULM stable some time ago but there is no intent in merging all of it. Mostly due to changes to ray tracing API that are different than the direction that engine took. I think it actually going to be safer for you if you use his plugin (which seems to be well maintained) instead of using the engine’s version.

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hi @anonymous-edc , @AleksJN

Firstly you must use the correct posting in the Conference/thread

Update to the Epic GPULightmass for 5.8.2 current 8th September 2026 - Development / Rendering - Epic Developer Community Forums

This post is regularly updated.

This uses the original update method from Luoshuang’s GPULightmass Unreal Engine 5.4.3

This overwrite the original 5.* Production Binary in both cases.

Luoshuang’s GPULightmass Unreal Engine 5.4.3 was the last update for the original baking method. Due to severe technical problems causing corruption of projects in later versions

In my case work stopped and as the Unreal Engine 6.* (UE5/UEFN) scheduled Q4 2027 wont be any updates as the only version is to build from source which is little interest to developers.