Subject: UE 5.2 Ray Tracing Reflections Not Working Standalone (SSR Disabled)

Development Rendering
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Bug
Bug1920×1080 114 KB

Hello,

I’m troubleshooting an issue with ray-traced reflections in Unreal Engine 5.2 and seeking some assistance.

Project Setup:

Engine Version: UE 5.2 (City Sample project)
Project Settings: Global Illumination set to Lumen, Reflection Method set to Ray Tracing.
Scene Details:
My scene includes a chrome sphere, a bright emissive cube, and a point light.

Problem:
Initially, I was addressing flickering reflections. To ensure only ray tracing was active, I’ve taken the following steps in my Post Process Volume:

Set Screen Space Reflection (SSR) Intensity to 0.0 and Quality to 0.
Reduced Lumen reflection values.
Enabled Ray Tracing Reflections, configuring Max Bounces and Samples Per Pixel.
However, with SSR fully disabled, the chrome sphere now shows no reflections of the emissive cube or other scene elements.

Observation:
Reflections do appear on the chrome sphere when Lumen reflections are active, but they disappear when I rely solely on Ray Tracing Reflections as configured above.

Question:
Does Ray Tracing reflection in Unreal Engine 5.2 function completely standalone without any Screen Space Reflection or specific Lumen interactions, especially concerning reflections of emissive materials? Or are there additional console commands or particular material setups required to ensure ray-traced reflections render when SSR is completely off?

Any guidance or troubleshooting advice would be greatly appreciated.

Thank you!

2

Hello there @SL33P3R_C3LL!

Checking around the community, the main deal here is standalone Ray Traced Reflections are largely deprecated and not fully supported as a completely isolated reflection method, especially for complex lighting scenarios like emissive materials. Most of its previous, standalone functionality has been taken over by Lumen.

When you set your project’s “Reflection Method” to “Ray Tracing” in UE5.2, you’re not necessarily enabling an entirely separate, older ray tracing reflection system. Instead, you’re often telling Lumen to utilize hardware ray tracing for its reflections where applicable. If you disable SSR and reduce Lumen reflection, the result is basically cuting off the reflection pipeline.

And regarding commands that could adjust or enable certain features while SSR is shutdown, there are methods to apply from old documentation related to UE4, but I would not recommend trying to enforce it. Please check the data below, and experiment with your build, until you can find a middle ground: