Would you mind giving a breakdown of what some of the settings you change do exactly? I play without the fake player light and have been on a quest to find the most "realistic" looking settings with RTX tweaks. This mod seems to be a good idea in that just increasing the "Global Light Impact" and the "Direct Light Impact" works but can create an unnatural look to some scenes (I have been tweaking those with the Cozy Fires mod).
It seems that "LightCullingDistanceTweakCoef" is the change here that is doing most of the work right? I'm trying to find an optimal setting for it that adds light to interiors etc. without over doing it. Are there other similar settings that could be tweaked for that as well?
Curious about the tweak of the ProbeBouce Impact to 0.983 as well.
Controls whether the engine uses a faster, less accurate tracing method for dynamic objects.
false = use full-quality traces on things like moving characters, objects, etc.
✅ Better visual fidelity, at some performance cost.
I would also recommend this mod https://www.nexusmods.com/witcher3/mods/3027?tab=files but it needs an update for it... it can change how far light sources can spread light via scripts but i think it cpu/gpu intensive and has a few down sides still a gem of a mod.
also you might wanna play whit these settings DisableAllCameraLights=false DisableBigCameraLights=false DisableSmallCameraLights=false set them to true and have no editor camera place lights
you would want an ENV that disables fake lighting in cuteness and or in gameplay.
Expect trade offs and some light bugs with all the mods you might gain some light realism but will face the tradeoff of light bleeding and some other anomalies in certain places... The game was not build from the ground up for RTX
One thing I've noticed in very low-light scenes is that when rotating the camera, you can get an "ambient glow" effect around the edges of objects that goes away when you stop moving the camera. It happens when this mod and your RTAO mod are enabled. I'd assume that effect might be caused by one of the settings in the RTAO mod, and it still very playable, but I was wondering if you might know what setting it would be caused by or if there is something that could be turned up/down to prevent or limit it.
Might just be a limitation of this RTX implementation though, which is fine.
Uber rtx lighting he made it after me(date) and its more user friendly. i think the magic of his mod is that you can scale up the intensity of light by tweaking GlobalLightImpact DirectLightImpact etc i try to scale those down and increase the distance at witch light from sources gets cut off via LightCullingDistanceTweakCoef witch is very tricky since it can cause light bleed in caves an indoor. In short they are very similar his is way easier to setup and UI friendly but dose not save values i think?
I have been going through these settings to change to my liking, but only a few of them seem to make any noticeable difference. I tried most of them in multiple different scenarios and lighting conditions, to no avail. Does anyone know of documentation anywhere, where these settings are discussed?
Could you post comparison screenshots between Vanilla RT and UberRTXGI Light? Especially in some dark places like caves or interior and night where Vanilla RT is way too dark and details are unrecognizable
46 comments
It seems that "LightCullingDistanceTweakCoef" is the change here that is doing most of the work right? I'm trying to find an optimal setting for it that adds light to interiors etc. without over doing it. Are there other similar settings that could be tweaked for that as well?
Curious about the tweak of the ProbeBouce Impact to 0.983 as well.
Appreciate the work, thanks.
🧾 Your Mod Settings Breakdown🟡[Rendering/RT]These are general ray tracing rendering options.🔶
GIAlphaTestMipLevel=1.000000
- Controls how alpha-tested geometry (like leaves, fences, etc.) interacts with ray-traced global illumination.
- Higher values = fewer fine alpha details affect GI (e.g., foliage blocks less light).
- 1.0 is a balanced setting, good for avoiding over-dark or weirdly shadowed foliage.
🔶RT_Cull_More_Than_DiagSize=320000.000000
- Sets a distance threshold for ray tracing culling.
- Essentially: "If this object is beyond this screen-space diagonal size, don’t bother tracing rays on it."
- Higher = less aggressive culling = better visuals, but more GPU load.
🟢320000is extremely permissive, likely intended for minimal culling — very cinematic.[RTXGI]This is where the Global Illumination magic happens.🔶
LightCullingDistanceTweakCoef=64.000000
- Controls how far away lights can be before they’re culled (turned off).
- The vanilla setting is much lower (around 1–2 in many cases).
- ✅ YES, this setting is doing most of the visual lifting if you feel interiors are more "filled in" and moody.
- 🧠 Tweak recommendation: Try
🔶64.0is drastically extended, meaning even distant light sources (like torches in a hallway) still emit light — especially helpful in interiors.32.0or48.0for a balance between realism and performance if 64 feels slightly "floodlit" in some spaces.GlobalLightImpact=1.141593
- Scales the overall brightness and strength of global illumination (indirect lighting).
- Above 1.0 gives a nice bounce-light feel, but can make interiors look unnaturally bright.
- Cozy Fires mod benefits from this, but you’re right to be cautious — too high can flatten contrast and make candles or fireplaces overpowering.
🔶DirectLightImpact=1.097000
- Controls direct lighting strength (e.g., sun, torches, magical light).
- Slight bump from 1.0 can help preserve crisp shadows and directional light power, which works great with enhanced GI.
- Be careful not to raise this too far above 1.1, or you’ll get harsh lighting without softness.
🔶ProbeBounceImpact=0.983000
- This is a very elegant setting: it scales how much bounced light (indirect from surfaces) contributes to the scene.
- ✅ Excellent value for realism. Would only reduce this if you're trying to create more moody, darker interiors.
🔷0.983is just under full — meaning you’re getting near-max realistic ambient bounce, but avoiding overbright scenes.[Rendering/RT/AS/Config]🔶RTConfigFastTraceDynamic=false
- Controls whether the engine uses a faster, less accurate tracing method for dynamic objects.
- ✅ Better visual fidelity, at some performance cost.
I would also recommend this mod https://www.nexusmods.com/witcher3/mods/3027?tab=files but it needs an update for it... it can change how far light sources can spread light via scripts but i think it cpu/gpu intensive and has a few down sides still a gem of a mod.false= use full-quality traces on things like moving characters, objects, etc.also you might wanna play whit these settings DisableAllCameraLights=false
DisableBigCameraLights=false
DisableSmallCameraLights=false set them to true and have no editor camera place lights
you would want an ENV that disables fake lighting in cuteness and or in gameplay.
Expect trade offs and some light bugs with all the mods you might gain some light realism but will face the tradeoff of light bleeding and some other anomalies in certain places... The game was not build from the ground up for RTX
Might just be a limitation of this RTX implementation though, which is fine.