How to reduce noise for Lumen in 5.4? (It's a lot worse than 5.1)


I am trying to update a project from 5.1 to 5.4 and I noticed that the quality of Lumen seems a lot more noisy and unstable in 5.4.2 compared to 5.1.

This is the comparison from Default 5.1 Unreal Third person character project with lumen on compared to 5.4.

5.1 Default Third Person Scene with Lumen on:

5.4 Default Third Person Scene with Lumen On:

As you can see the shadows on the side of the cube are really noisy in 5.4 compared to 5.1.

In an environment with more objects this noise becomes a lot worse and really distracting.

Is there a way to reduce the noise and get similar results to 5.1 in the current 5.4.2 engine?

Any help is appreciated!



This has been and continues to be a thorny issue in my side. This technology is in its infancy, so I suppose we need to be a little understanding of that.

With that out of the way, I found a few ways to mitigate this issue:

  1. With the POST PROCESS. You can create a softer effect from the lighting that can smooth (all) edges.

  2. You can increase the “Final Gather Quality” in the POST PROCESS.

  3. Check out information on Lumen and how it bounce-lights objects here:

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this is ambient occlusion, not shadows. tsr or taa usually smoothes it.

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Hi! Sorry I mispoke about the shadows vs. AO. You are correct the issues is more with AO.

Do you know what the ideal settings are that smooths the noise? The default settings don’t really seem to be doing much.

Thanks for getting back to me!

What is the “lighting” setting in Post Process you mentioned in your reply? The link you posted seems to be hinting at applying additional console commands.

I am hesitant of changing quality settings since it will impact performance for the project I am working on. It’s a shame that the difference between the two engine is so much. I wish I could at least get Lumen to look like the 5.1 version without having to tank performance.