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Light seams when using in-game building system

I'm working on an in-game building systems (like Space Engineers or Ark), but there is a bit of light shining through the seams of my walls. Full sized blocks seem fine, but the thinner walls have the problem. Screenshot here:

alt text

Is there a straight forward fix for this? I've looked through a bunch of settings and posts and haven't found an answer. The rest of the level is the first person shooter starter setup, so just a single directional light setup, no settings have been changed.

Product Version: UE 4.18
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asked Dec 31 '17 at 06:14 PM in Rendering

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Brandon Wamboldt
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avatar image Makigirl Dec 31 '17 at 06:30 PM


So one "building" is made out of 5 wall pieces and you have problem with just the top ones? :S /pic is really small sry/ Can you tell me please what quality is your build? Also could you show us the lightmap uv of the problematic mesh? ...to be honest I haven't seen light leaks for a long time... not even with plane walls... so it's for sure not the thickness of your wall!

avatar image Brandon Wamboldt Dec 31 '17 at 07:40 PM

Sorry, it's made 4 pieces on the top (its a 2x2 building). I'll try to figure out how to get the lightmap uv, but it's just a 200x200x6 cube I exported from Maya. There is no additional detail.

avatar image Makigirl Dec 31 '17 at 07:50 PM

Just double click on your mesh and on the upper part of the detal window there will be an UV button. Please select the channel you set for the lightmap and take a screenshot! ;) ...I still don't understand the modular pieces... 4 pices/wall/side you have? Or the whole "building" is from 4 pieces? :S

avatar image Brandon Wamboldt Dec 31 '17 at 08:00 PM

Here is what it looks like: https://i.imgur.com/O7VUb4f.png

Here is UV channel 0: https://i.imgur.com/d7sZ4oc.png

Here is UV channel 1: https://i.imgur.com/bPKUfJq.png

And another picture that better shows the issue: https://i.imgur.com/WnqSCoK.png

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Thank you! Not the best lightmap! :S All faces should be separate! You see lighting information can leak like this from one face to another! Because meshes calculated separately if you have a continuous flat surface "break up" into pieces, they tend to have shading differences! You can solve it by reducing the Indirect Lighting Smoothness (0.6) in the world Ligtmass settings! ...usually it works with reduced Scale (0.1) and increased Quality (10). It will increase build time but you will hve a nice clean bake!

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answered Dec 31 '17 at 08:38 PM

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avatar image Brandon Wamboldt Dec 31 '17 at 11:17 PM

I've separated the UVs and applied the lightmass settings but it didn't fix the issue. Just to re-iterate, these meshes are placed DURING gameplay as part of a dynamic player building system (e.g. space engineers)

avatar image Makigirl Dec 31 '17 at 11:30 PM

SORRY!! I was talking about static lighting!! :S Forget EVERYTHING I've said!! :S

avatar image Brandon Wamboldt Dec 31 '17 at 11:34 PM

Do you think its because I use snapping and place them exactly next to each other? Do I HAVE to have like 1 unit of overlap? It'll make it more difficult to implement :(

avatar image Makigirl Jan 01 '18 at 12:32 AM

I think it's the best if it's snapping!

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