How to fix lightning?

I need to create more realistic lightning inside house))) And fix these lines on walls.

There is honestly lots of things you would have to go over if you trying to get achieve a realistic look.
. As far as the light bleed. look more into Your UV mapping and make sure your objects are snapped together.Here is a few things and tools you should look at and study to try and achieve your goal

1.) Your Directional Light
2.) Post processes settings
3.) UVs mapping and UV resolution on your mesh
4.) Material creation "EX normal maps, bump maps, etc…
4.) Reflection Captures

Epic posted documentation on this and also have a level you can check-out under the learning tab in your unreal launcher.


I’d like to add some additional info to kingaoe3’s answer if it helps:
You should watch/read posts or tutorials about archviz in unreal because you’ll be getting way more information there. Learn from scenes like Koola’s stuff (you can get his Lightroom Interior Scene for free to check his settings). Read Unreals Lighting Basics and use as few lights as possible and set them to static wherever possible (Volumetric Lighting in 4.18 will help).

Change your Lightmass Settings in World Settings. Level Scale to something lower, like 0.3 if you can afford the building times, Indirect Lighting Bounces to 4 or higher (anything above is mostly placebo but you can try higher values), increase Indirect Lighting Quality, smoothness maybe a little lower to 0.7 for sharper shadows, etc. It depends on your preferences and what you can afford perfomance-wise.

Place Light Portals in your windows and scale them to fit the frames

For the white light coming from the outside you can either use a directional light if you like the effect of sunny spots or a skylight/spotlights with inversed square falloff activated and facing away from the windows directed at a white plane (which is used as a reflector to bounce soft light into your windows).

In your Build-Settings, try to build on higher quality than Preview to get better results. Of course this increases the build-time.

Adjust your Lightmaps: seperate your objects so you can change their lightmap-size individually under details to tomething higher, according to their importance or scale (large walls should get 512 or 1024+). Read this and make sure to have enough padding between your shells to avoid light bleeds: Unwrapping UVs for Lightmaps | Unreal Engine Documentation

If you want a quick simple way to have a white exterior, just use your Exponential Height Fog, turn it’s color to white and set the Height Falloff to something like 0.00001. Turn on Volumetric Fog and adjust the exponent and the density accordingly.

Use the Exposure on your camera in Details/Lens or with a (global) PostProcessVolume instead of fiddling repeatedly with each light’s brightness.

I hope I could help you!