Seams and weird shadows in Modular Meshes

Hi, I have some issues with shadows and seams between modular meshes. I’ve gone through some answers and adjusted my UV’s to have at least 2px spacing between each UV island and that the UV’s are snapped on grid.

These screenshots are with
Static lighting level 1.0
Indirect lighting quality 1.0
Indirect lighting smoothness 1.0

Adjusting these to
Static lighting level 1.0
Indirect lighting quality 2.0
Indirect lighting smoothness 0.6

Makes the shadows more wavy and the seams to be much less but I cannot eliminate them and the trade-off for bad shadows for less seams seems to be a bad way to proceed.

Decreasing the Static lighting level to 0.1 makes it even worse

Lightmap resolution for the meshes are 64, increasing them also gives me the same result

This links shows that modular building is possible

There are some other threads which states that it is not possible because each mesh is rendered on a different thread causing the seams.
Ref to that : How to fix blocky shadows across modular walls? - Rendering - Epic Developer Community Forums

How do I fix these issues ?

Hi Switchblade,

I’ve covered the shading issue you see between modular pieces here on my Lighting Wiki guide: A new, community-hosted Unreal Engine Wiki - Announcements - Epic Developer Community Forums

This guide includes some tips for getting rid of the issue. Ultimately, for something like your wall you would be better to use a single mesh for the wall or other geometry to cover these seams. Sometimes over-modularizing your scene is not the best option and just increases draw-calls that need to be performed and gives you results like this. Hopefully, we can fix this in the future and this won’t be an issue, but as far as I’m aware there are no plans at the moment.

The wavy shadows are due to low lightmap resolution.


Thanks Tim, I’ve gone through your guide and found it really useful. Can you give me any reference videos to where using other geometry between the seams would solve the case ? And by doing so can I still follow the methods used by bethesda studios in their modular level creation (ref : Joel Burgess: Skyrim's Modular Level Design - GDC 2013 Transcript )

I know it’s been five years but Tim, do you have a back up of that article? The new wiki only seems to have saved like 10% of the old article.