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Strange Light bug

Hello everyone,

I have that strange bug, that when I place a light inside the object prepared for the lights, the outside of the mesh starts to shine. But as far as I checked, there are no mesh errors, or open parts where the light could shine through. I am helpless I have no clue what it could be.

First I just placed a point light inside this tube but when I baked the light, I was shining outside. So I used a spotlight and put it outside. But that did not work well, because like this, the room is illuminated but the lights look like there were out. This is really strange looking. So I tried to combine both. Illuminate the room with spotlights and use a point light with small attenuation radius to illuminate the lamp itself, but that did not work because it started to glow again on the outside..

I would be so glad if anyone knew why this happens.

Btw: I am a total Unreal beginner, so I am pretty sure this could be a totaly obvious crap :x

Thank you in advance.

Product Version: UE 4.21
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asked Feb 15 '19 at 02:51 PM in Using UE4

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2 answers: sort voted first

You can sometimes get this kind of lighting issue if your mesh has zero thickness. You need to make your tube solid if you have a light inside there. But most people don't do it that way. Most people would make part of the mesh emissive, so that it looks like it is shining and then use a spotlight outside the mesh.

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answered Feb 15 '19 at 03:47 PM

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Surfaces by default only block the light in one direction. Is it possible that your mesh surface is not pointing the right way to block the light?

One easy thing to try is to use Two Sided Lighting on the mesh or make the material two sided in general. You should be careful not to keep it like that if you don't want to impact performance, but it can be an easy way to search for the cause of your problem.

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answered Feb 18 '19 at 06:56 AM

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Warner V
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