Hi everyone,
I’m encountering a frustrating issue with reflections using Lumen in Unreal Engine 5.4. I’m working on an ArchViz project featuring a 3D house model, which has two Post Process Volumes:
- Exterior Post Process Volume – This is unbound with a priority of 0.
- Interior Post Process Volume – This is not unbound with a priority of 1.
The Problem
I have a mirror in a bathroom scene (a scaled cube with a mirror material: Base Color = White, Metallic = 1, Specular = 1, Roughness = 0). While the reflections look fine outdoors, they become blotchy and filled with black splotches when the mirror is placed inside. Adjusting Lumen settings doesn’t seem to make any difference.
I initially thought it might have been something in the Post Process Volume messing it up, so I tried turning off the Interior Post Process Volume completely, but the issue still remains.
Here’s what’s happening in the attached images:
Image 01:
This shows the mess of reflections in the mirror and shower. Black splotches dominate the reflections, and they’re very inaccurate overall.
Image 02:
The mirror is just a simple cube scaled into place with a mirror material applied to it.
(I tried replacing the cube with a plane, but its the same issue).
Image 03:
All the Lumen settings I’ve tried adjusting are shown here (Final Gather Quality, Reflection Quality, etc.). No matter what values I input, it doesn’t seem to make any difference to the scene.
Image 04:
The Post Process Volume clearly affects the scene, as changing settings like temperature applies to the entire environment. This confirms the object is inside the Post Process Volume.
Image 05:
The material applied to the mirror couldn’t be simpler: White Base Color, Metallic = 1, Specular = 1, and Roughness = 0.
Image 06:
The same mirror placed outdoors shows near-perfect reflections, with no black splotches or artifacts. This confirms the issue is specific to the indoor environment.
Additional Notes
I’m using Lumen reflections because ray-traced reflections have been removed in UE5.4.
This only happens indoors—when the mirror is moved outdoors (as shown in Image 06), the reflections look perfect.
Has Anyone Seen This Before?
Does anyone have suggestions on how to improve the indoor reflections or resolve these black splotches? I’d really appreciate any advice or insight!
Thanks in advance!
J