Ray tracing light count

Hello guys !

Since the 5.1 update a warning is show when the maximum number of active ray tracing lights is equal to or greater than ‘RAY_TRACING_LIGHT_COUNT_MAXIMUM’

I would like to know where i can upgrade this value or find an other solution

Actually all my light have a draw distance but even if i don’t render them the light is still count on a current actuve ray tracing light

Thanks :smiley:

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Im having the same issue, any fix for this?

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I’m also experiencing this same issue. There is the command “r.RayTracing.GlobalIllumination.MaxLightCount” but it doesn’t seem to have any impact on the scene or the error message displayed in the viewport.

I’m also experiencing this issue and have not found a solution yet.

Problem for me too

I got a semi-decent solution to those who DON’T intend on using ray tracing but only wants that message to go away
Basically go to all your lights, search “ray tracing” in the details and disable the 2 options that show up under the “Light” category. If you can change the Ray Traced Shadows option, disable that too

If you intend on using Ray Tracing, I unfortunately still don’t know how to increase the limit

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Would like to see a follow up on this!

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Same here, no solution yet…

It works on 4.27, but the lighting effect is not good.

I also have this problem.

I too have this issue but I wonder if the solution isn’t just to add the Nvidia RTXGI? I know it was working in UE4 but I haven’t tried it in UE5 yet. Has anyone else?

Disregard! I found out UE 5.1 isn’t supported by RTXGI at this time.

Tried it with NVRTX branch for UE5.1 and limit is there.
NVRTX should have RTXGI included.

Also found this response in another thread, but did not test it yet:

The new warning you are seeing is only for real-time rendering, which has always had a limit of 256 ray traced lights. Now at least you know when you’re going over the limit and can adjust your settings accordingly. This warning does not apply to the path tracer, which has practically no limit on the number of lights. (There is technically an internal limit but it would be very hard to reach.)

me too the same problem. how to solve it?

Just solved it.
Download an uncompiled version of UE NvRTX. follow NvRTX installation until you are in Visual Studio just before building. Search for RAY_TRACING_LIGHT_COUNT_MAX and change value of LIGHT and DECAL, like in picture bellow, to 2048. You have to set up the search to look for file contents. Save and build UE. Run UE.

You probably do not need NvRTX, any uncompiled version uf UE would work, just NvRTX handles Ray traced lights much better.

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Hi! I’ve done this. but the plugins are not compatible. any help what could be done? thank you!


You need to download the version that’s compatible with your plugins, then you can go to the offical unreal engine source files that you downloaded from epic games launcher. then go to the plugins folder and copy the plugins and it will work.

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