Mirror with Lumen is horrible

May be I’m making something wrong, but it is impossible for me to make a mirror with Lumen’s reflections.
I saw videos where they make this mirror in Unreal 5 and it seems pretty clear, but I don’t understand how he did it. I don’t want to use ray traced reflections. You can watch here:

And this is my mirror:

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ouh nouhhh

The answer is in the description of that video:

Lumen Reflections works similar to Screen Space Reflections but with the quality of planar reflections. It is really high quality accurate reflections but only when the reflected parts are visible in the screen. Otherwise I think it falls back to a low quality reflection, which seems like is generated using Mesh Distance Fields.

Which is correct. Read the screen tracing section in the docs.

So you need to use planar reflections.

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Same thing, testing reflective surfaces with Lumen looks absolutely low res. Made a video with basic stuff. Boosting Lumen reflections quality to magic number 4 does help but then the GI stops getting reflected in the reflections. Tried increasing final gather lumen quality as well as lumen resolution in project settings from 2048 to 4096 which also helps but very tiny bit, the final reflection is still very much unusable.

So while setting lumen reflection quality to “4” in postprocessing volume helps, right now you need hardware RT for this to look good. Maybe by release the highest lumen software setting will work better, but not right now.

This. Right now setting it to ‘4’ (past the ‘2’ slider cap) will give max quality.

Their goal is to have Lumen reflections eventually offer same quality as RT reflections. Reason why they are deprecating it.

Hello, at the first go to project settings from Edit menu
1- Engine-> Rendering-> Global Illumination: sit on [Screen Space(Beta) ]
2- Engine-> Rendering-> Reflections: Support global plane for Planar Reflection: set On
3- Search [motion]: set Off
4- Make mirror material and search Reflection, set On: High quality Reflection & Planar Reflection
5- Put Planar Reflection in front of mirror,
6- Go details, set value of Normal Distortion Strength & Prefilter to [ 0 ]
7- Set value Screen Percentage to [100]
**Congratulation **

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I’ll just add something hear for anyone recently looking at this thread: I believe they’re talking about EA, UE5.0 has much improved lumen reflections, including performance, temporal stability, and in some cases feature improvements. 5.1 also offers its’ own improvements, so I’m essentially saying lumen reflections are much better than the ones currently documented here.

Kinda cringe, I even tried UE 5.3 build and like planar reflection is a blurry plane that’s not helpful. And like a billion combinations of lumen and screen space reflection properties you can’t get rid of the shadow artifacting, weird funny lines… Idk, feels like just something nobody bothers with in the UE pipeline…

Really? This is a mirror with unreal 5.2 with highest settings possible…

What’s your shadowing method, if I may ask?

Virtual shadow maps, but even with shadow maps it’s the same.
Ray traced shadows is not enabled because it messes up all metahuman clothes, but even enbabled doesn’t change the situation
In outdoors is even worse…
The only solution at the moment is still planar reflections that is very heavy
Capturescene2d seems that is not working anymore with last updates…

I have never seen lighting behavior like that before.

That complete darkness is baffling to me, the surface cache should be providing acceptable coverage for everything in general. Could you post your PPV settings please?

I use camera settings instead of post process volume. Anyway what do you need exactly? They are many things that I can show to you. Maybe there is a fast way to send all together…

I just spent a long time looking into this. The short answer is that it is not currently possible to make a decent mirror with Lumen. My project is not interactive and will be delivered as a video so I had to set up the rooms with mirrors in a separate map which where I baked the lighting and used a planar reflection for the mirror.

It’s the same thing I’m doing too, it’s just so ■■■■ heavy. I can barely navigate the scene with planar reflection active. and rendering time are double. More than owing a rtx 4090 I don’t know what to do. Any suggestion to make it lighter without losing quality?

A few visualizations of your surface cache would be wonderful, or just the project file itself I suppose. By and large your behavior seems very unusual compared to what I normally see with lumen.

here the surface cache screen.
Let me know if you need also the scene, because it’s very heavy, more than 200 gb. You know I use it as my object library container so…
But if you need I can try to export this level in a new one

Yep, that would definitely be the problem.

Your surface cache is essentially how well lumen parameterized your scene. The yellow is things it cannot cover (EG skinned characters), and the pink is what it refuses to cover because of memory expense. Your scene looks as poor as it does because significant portions of it have zero surface cache coverage, meaning they’re just returning black and don’t affect GI.

This can be fixed, but it partly depends on how you did it to begin with. I know that lumen interacts with the foliage tool in strange ways, but if this was done with foliage, make sure ‘affect dynamic indirect lighting’ is checked.’ Also, crank your lumen scene detail as high as it will go to get some amount of coverage there.

Failing all else, you can also solve this by simply cheating the lighting. Place a series of rect lights around the scene to mimic the sky light. Lumen can get lighting in reflections assuming there’s an analytical light source, which the sky light technically isn’t.

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Of course, that won’t make it lighter necessarily. Honestly, the only real way to get good reflections in lumen is to either A. author all of your art to very specifically cater to its’ limitations, or B. throw immense amounts of processing power at it.