UE 5.0.2 - Mirror Reflection Shadows Too Dark - Ray Tracing


I’ve created a mirror to be used in a sealed off interior. No outdoor lighting, skylight, etc.

The shadows in the mirror reflection are way too dark as you can see.

  • I’m using ray tracing for reflections and shadows.
  • My interior lighting consists of spotlights and rect lights.
  • I’m not using planar reflections or sphere reflection captures.
  • I’m using Lumen global illumination.

I’ve seen multiple mirror examples online which reflect the shadows correctly - but unfortunately there is no explanation on how they managed to do so.

Is there an easy fix for this?

Cheers.

EDIT: Same scene with path tracing:

Hey Gatzkerob,

I am on the same mission as you, creating a real time mirror.

In short there is a limitation with Dynamic GI and reflections, it just isn’t quite there yet.
More of an in-depth answer is here.

Basically your best bet is to use standalone Ray trace reflections with Lightmass GI to get the results you want.

I actually didn’t know pathtracer worked with dynamic GI that’s cool. That will be great for stills.

Good luck, I know I am still tinkering with my mirror a bit, but for the most part I have it working with Lightmass and RT reflections. Sucks we can’t use lumen yet for it.

Thank you for referencing my post! I’m happy you found it potentially useful.

Everything you said was spot-on, RT reflections with lightmass is currently the only way to achieve good-looking mirror reflections. Both lumen GI and reflections are high-quality for the first bounce, and then reduce fidelity significantly. It works great for most game use-cases, but breaks in many Archvis scenes.

And the path-tracer is an interesting beast, it supports full dynamic GI/absorbsion/transmittance, and can get pretty much the best results you need. Lumen can match the path-tracer’s diffuse lighting identically, but not anythiing specular.

Good news down the line though: lumen reflections for Lightmass, and multi-bounce specular are on the list of features they want to add, it just may take a while.