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Emissive Light - Weird Shadows


I have a problem with emissive lighting. In a basement scene, there are only emissive light on ceiling, but reflections on wall is weird and lighting results are totally failed. wall lightmaps resolution 1024.

where is the problem?

alt text

Product Version: UE 4.7
emissive_1.png (384.2 kB)
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asked Jun 02 '15 at 09:37 AM in Using UE4

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2 answers: sort voted first

Hello there. ^_^ That sure does look funky! ^-^ Could you go into the Static Mesh editor and click on UV and then click UV Channel [number] and pick the last on the list, and take a screenshot, please?

Ah, and make sure that it's the Light Map Resolution that is set to 1024 (it's a bit high but since I don't know what your project is about, I won't tell you to lower it) and not the Min Lightmap Resolution. I did that a lot at first. ^_^'

I hope you get it to work! :D

Oh! Just in case you have not seen this https://wiki.unrealengine.com/LightingTroubleshootingGuide

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answered Jun 02 '15 at 02:21 PM

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avatar image goergingo Jun 02 '15 at 02:28 PM

here is the static mesh editor screenshot. By the way, everything is OK when i use point light.

avatar image goergingo Jun 02 '15 at 02:29 PM

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emissive2.jpg (311.7 kB)
avatar image goergingo Jun 02 '15 at 02:33 PM

i read this file thank you so much :)

here is the screenshot when i use point light:

alt text

emissive3.png (930.2 kB)
avatar image Tim Hobson ♦♦ STAFF Jun 02 '15 at 02:52 PM

Hey Goergingo,

When you say you're using emissive lighting for your scene, do you mean Emissive material used as a static light? This would mean that the Emissive light is getting baked into the texture as static lighting.

If that's the case you'll want to increase the lightmap resolution since emissive lighting quality is dependent on this otherwise you'll get artifacts.

You may also want to consider breaking up the wall into more modular chunks, For instance, a long wall piece and the column part would be a single mesh instead of the long wall as a single piece. This would give you better use of the 0,1 space in your UV so that it can use more room and get closer use to the full 1024 lightmap resolution quality.

This is kind of a contradiction to what Eric and I wrote in the Wiki Lighting Guide, but emissive lighting for static is a little different.

If I'm completely wrong and you're not using emissive for static lighting I need to know more about your scene.

In your Global Post process disable Bloom and lens flare for the moment, as this makes it easier to diagnose any light leaking or issues that get baked into the lightmap texture.

  • What is your light source for the ceiling lights? Point or spot light?

  • Do you have a directional light that is behind your walls? If so, disable this and rebuild lighting to test.

Let me know.


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I've seen this issue before when using a low "Indirect Lighting Smoothness" in my lightmass settings. Both images are using emissive static lighting.alt text

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answered Nov 16 '18 at 11:46 PM

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