Shadow artifacts

Hey guys i’m very desperate. all of my architecture ( walls, floors etc…) makes weird shadows and artifacts. i looked every tutorial on entire youtube. i’ve set my UV maps in a bunch variation. lightmap resolution from 64 to 4096, it gets more wierd. i’ve tried to model my room everything seperate and seperate UV’s . the entire room as one with one UV…nothing… everytime weird shadows. lightning from preview to production…nothing helps.
i’ve adjusted the lightmass settings. set the lightmap coordinate manual from blender in a seperate UV channel and tried to generate it from UE4 itself…absolute nothing changes
i’m using Blender to model my static meshes …the strange thing about it is that complex things like a bed cover has perfect shadows but a simple cube makes strange shadows but is has the same setting and right UV unwrap too

Hello simerti,

What I suspect is happening is that your seams in your lightmaps are at those corners. What happens with seams is there is essentially a break where the calculation is taking place. This can cause artifacts and the black lines as you see. I see you have tried some of the other troubleshoots already, and I believe your lightmap UV’s are causing an issue.

If you would please provide a screenshot of your UV’s along with your lightmap UV’s I will take a look at those.

Also, I am linking your to our documentation on how to unwrap for lightmaps.


hello thanks for your reply :slight_smile:

it seems that the shadows have a false resolution, they are very pixelated.
but its already on 1024px and higher it gets more weird or chrashes my computer…other static meshes like the bed have on 64px better shadows

sorry for the seperate posts, the site wont let me upload the pictures at once

There seems to a few problems that I will cover in order of your first screenshot.

Looking at the light map UV’s from your screenshot I see that the seams for the lightmaps are on every corner. This way each face is separate. With lightmaps the more optimized your UV space is the better your lightmaps will look. To that end what you can do is weld the seams of your cube on all sides but the bottom. This way, when viewing the scene, the player will never see this side. There is no way to truly hide all of the artifacts that you see but there are ways to minimize the effect. This is covered in the documentation above. To weld the seams you will need to export this to an external modeling software and make the welds there. If these cubes were created in an external software you can make the adjustments and reimport them.

Now, the second picture you have posted illustrates static lighting with a shadow cast on your geometry. With baked lighting you are getting a lighting calculation that is built when you build lighting. That calculation is then drawn on screen. This calculation happens once and does not update like stationary or movable lighting. As a rule the quality and accuracy of lighting from least to greatest is static/stationary/movable. Switching to stationary or movable will clear up most of the pixelation you see. Even when increasing the resolution to higher values like 1024 you will see this pixelation.

I am linking you a page that describes static lighting. Make note of the screenshot at the bottom and the quality of shadows even after increasing resolution.

I am also linking you to our documentation on stationary and movable lights that explain their unique parameters and how they can be used to improve lighting and shadow quality.

Lastly, I am linking you to a lighting troubleshooting guide that will cover common practices and troubleshoots for lighting.