There’s a similar issue posted above; is your emissive material Unlit? That will be ignored by GPULM.
Hi yujiang, I did read @anloarq’s post and replies,
my emissive material is set to Surface, opaque, default lit,
the mesh is set to static, emissive light source, lightmap - force surface.
and you can see the red ball is still not lighting up the surrounding objects after bake.
I have also uploaded the minimal project file in the previous post that you can try it. thank you
This is what you need:
Meanwhile, your cube’s UVs are not suitable for lightmaps as the UV islands are sticked to each other. I enabled Generate Lightmap UVs with a Min Lightmap Resolution of 64, darkened the light and the emissive source, and I got this:
The denoiser hates lights that are too bright:
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aha that’s it, I only ticked the Emissive light source but over looked “Use Emissive for Static Lighting” under light mass advanced settings.
Its working now, thank you a million times!
Hi, just wanted to ask if theres support for masked materials (on substrate)
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and also, wanted to ask what “volumetric lightmap quality” actually means, does it help with the deringing issue?
Hi, this patch is incredible. Thankyou for maintaining this.
I have a question - do you know what the usual source of the build hanging at 99% is, and if there is anything I can change to reduce it? The initial build process is pretty quick, the denoise and texture write at the end is quick, but it sits at 99% for about 8 minutes out of a 10 minute build. The only relevant logs just show a jump:
[2026.04.28-20.14.55:730][324]LogGPULightmass: Cached ray tracing scene is invalidated due to material changes
[2026.04.28-20.14.57:323][324]LogGPULightmass: Cached ray tracing scene is invalidated due to material changes
[2026.04.28-20.14.57:603][327]LogGPULightmass: Cached ray tracing scene is invalidated due to material changes
[2026.04.28-20.22.22:901][734]LogGPULightmass: Cached ray tracing scene is invalidated due to material changes
[2026.04.28-20.22.22:925][734]LogGPULightmass: Cached ray tracing scene is invalidated due to material changes
[2026.04.28-20.22.23:109][736]LogGPULightmass: Cached ray tracing scene is invalidated due to material changes
[2026.04.28-20.22.23:291][736]LogGPULightmass: Cached ray tracing scene is invalidated due to material changes
This doesn’t happen during “bake what you see either”.
Not a massive issue, but I’d love to reduce it if I can.
I conducted a test with a simple Substrate masked material:
Both Blendable and Adaptive GBuffer are tested. GI bounces and shadows should work.
VLM’s quality multiplier is simply a multipler on GI samples, because VLM has no denoiser support.
Deringing is indeed missing from GPULM. I’m actually studying it to see what’s a good way to implement it in GPULM.
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Usually getting stuck at 99% means GPULM is processing VLM and its amount is huge.
For
LogGPULightmass: Cached ray tracing scene is invalidated due to material changes
It usually means you have something updating every tick invalidating the cache. Video textures could be one of them. It won’t affect the quality of the bake.
Okay thanks, this must be it. It’s before denoising - denoising is pretty quick. Overall this is much quicker than CPU lightmass so I’ll just live with it. Thanks again for all this - you’re keeping baked lighting alive.
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weird that it didnt work for me, will double check later
also REALLY great to hear any actual news on features like VLM deringing!