Lighting problems on plane walls

Oskar Selin · Jan 2015

Hello!

I'm building my first environment in unreal engine 4.6 and just ran into a problem i can't find any solution to.

The problem:
On the walls that the directional light is not affecting (darker areas) i get a dark line/seam between planes.

I get the same result after baking light at preview or medium quality.

I think the problem could be related to:
- The walls are planes
- Something with lightmassImportanceVolume settings or lightmaps

photonarbiter · Jan 2015

I think the issue comes from the quality of the build not being on production but I'm not 100% sure. Have you tried doing that? I've run into that issue in one of my projects as well.

Oskar Selin · Jan 2015

I will try a production bake overnight then. Thanks for the suggestion!

Oskar Selin · Jan 2015

I did a production light build last night, and most of the weird shading are gone on closeup. Though when i zoom out they pop back.

Do lightmaps have some sort of LODs? Maybe i could change to a higher lightmap-lod/resolution setting then? These are the lightmass settings i used:
static lighting level scale: 0.5
indirect lighting quality: 2.0
indirect lighting smoothness: 0.5

engine scalability settings: epic
material quality level: high

Obscura · Jan 2015

Yes the lightmap's mipmapping can be changed right in the lightmap textures (such as with any other textures). Dunno where they get stored in ue4, but in UDK, it store them into the level file, so If I view the content of the level file in the content browser, the lightmaps are insite that. Disable the mipmapping on them, and you won't get the seams anymore. However, really low resolution and highly divided meshes can still cause problems. Padding option should have been added ages ago though...

Oskar Selin · Jan 2015

Thanks Obscura. I already did the easy fix and replaced the worst areas with bigger boxes. I will try what you suggested for the other areas!

HAWK12HT · Jan 2015

Hi, hmm guess UE4 still got the same issue as UDK

https://lh6.googleusercontent.com/-BnQ9i8aQlhY/Tu5lH-ew8EI/AAAAAAAAABc/wgWepMjnBek/s800/KMFahad_8.jpg

https://lh4.googleusercontent.com/-AwmsLXKQS2I/Tu5lI69aaEI/AAAAAAAAABs/jdWxm_CZlBc/s800/KMFahad_9.jpg

https://lh6.googleusercontent.com/-hoy9wZsB2Sc/Tu5lIrhd-fI/AAAAAAAAABo/vC5-u680FNU/s800/KMFahad_10.jpg

Oskar Selin · Jan 2015

HAWK12HT, I've read your document twice but i can't really make sense of it. In short do you mean that chamfering all 4 edges of a plane will remove the shadow-seam?

HAWK12HT · Jan 2015

Yes either chamfer all sides a little bit or add padding on lightmap UV and cover the connecting parts with some sort of detail mesh on top to hide the seam.

Also simple color textures cause this issue too (concrete in your case)

Dont know if you have looked at older threads here under "lightmap seams" if not then do have a look at those too.

Obscura · Jan 2015

The general fix would be to not build the meshes modularly in the UE editor, rather use them in your modeling app, weld the sides on the mesh and on the uvs too, and then there is no chance for seams. This gives less freedom in the UE editor, but you completely get around the downsides of lightmass.

Oskar Selin · Jan 2015

HAWK12HT, okay i will have a look in the older threads! Would be nice to get a little bit more knowledge in this area.

Obscura, yeah that is a good fix but as you say it limits the possible mesh-combinations in UE. My next project wont be nearly this modular. And i will be very careful with small tileable wall-parts!

ZacD · Jan 2015

http://www.reddit.com/r/UE4Devs/comments/246whl/the_most_important_thing_about_lightmaps/

https://answers.unrealengine.com/questions/95423/lightmass-with-bad-shadow.html

Oskar Selin · Jan 2015

Thank you ZacD! I read the posts in the threads you linked and found a link to another one with Tim Hobson:
https://answers.unrealengine.com/questions/92819/lightmap-uv-alignment.html

Snapping the lightmap UVs according to the methods discussed in your links help somewhat. The biggest fix was splitting every hard edge and mapping them alone.

Clark Coots · Jan 2015

oo thank you for the links about cleaning up lightmaps in UE4/UDK with -2 grid snapping, very helpful!

Lighting problems on plane walls

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