Light leaks problem. Especially on SurfaceLight

[natandtyler9 (Nathanler)]

I’ve wondered why this hasn’t been fixed for several years now. When using ShadowMap or Voxel lighting technology (any option except Future), light frequently leaks through opaque parts. This problem also occurs with other light types like SpotLight and PointLight, but the leakage is significantly more pronounced with SurfaceLight.

In the accompanying video, you can see a room where a light source is enclosed within a box. I set the light’s angle to between 90 and 180, and its range to between 30 and 60. The light leakage becomes most apparent when both the angle and range are maximized. This issue has been widely reported by many users because it can significantly hinder player visibility or even make it impossible to discern objects in certain lighting conditions. As a temporary workaround, I’ve advised some developers to use lower values, such as an Angle of 100 and a Range of 25, to achieve more consistent lighting for fair gameplay.

Keep in mind, this not just happens on PC, also in mobile, tablet, console, VR on low graphics.

System specs:

OS: Windows 11 64-bit
CPU: AMD Athlon 200GE with Radeon Vega Graphics
GPU: AMD Radeon™ Vega 3 Graphics
RAM: 8 GB DDR4
Roblox Client Version:
Roblox Studio Version: 0.677.692.6771138 (64-bit)

Hope if something that we can discuss this further, I can’t wait to see your replies, thank you and hopefully this gets fixed soon.
Place2.rbxl (55.6 KB)

[ScrollFrameRotation (BannedFromTheDevFrm)]

i dont think this is a bug its just optimized lighting

[TigerRabbit2]

There are a couple of things going on here.

The most visible one is that surface lights do not cast shadows through the light voxel grid. Which means they leak outside of the building.

The other parts are better described by other people. E.g.

Light Leaking Through Parts

When building, I notice that the skybox influences the color of the light that leaks through parts. How do I fix this? What I've tried [Line] [RobloxScreenShot20210514_204253603_LI (2)]

PSA: the common advice about light leaking is incorrect

Often, when people ask about how to prevent light leaking, the common answer is that your walls must be at least 4 studs thick, as voxels in Roblox are placed on a 4x4x4 grid. This does not actually stop light leaking; you instead need your walls to be at least 6 studs (just over 1 voxel) thick. See below; on the left is 4 thick walls, and on the right is 6 thick walls (note that this is using Voxel): [image] Just a snippet of information I discovered while messing around in Studio …

These pretty much line with the statement “I don’t think it is a bug just optimized lighting”.

FWIW a lot of other engines have similar issues and this is largely due to the nature of how lighting works for rendering.