This is a test render baked at ‘professional’. Obviously, it’s not looking very professional. The blotchiness may be due to the lightmaps being left at default (64), but I’m more concerned about the tiling on walls, ceiling and floor. It should appear as one solid surface.
Open up the ceiling, floor and wall meshes and make sure they are using the appropriate UV channel for lightmaps. And you should increase the lightmap resolution as well; 64 is not enough for large surfaces like these.
It looks like you are making this room with modular pieces? Having them separate can cause this issue because each piece is worked on with a different thread during the light build, and the gradients don’t match up 100%. It’s not a guarantee, but you might be able to solve this using perfect lightmaps that have every edge snapped to a 64x64 grid inside your modeling program. See this thread for how to fix this modular shadow problem: Modular Asset Lighting Problem - Rendering - Epic Developer Community Forums
Towards the bottom of this thread, Hobson from Epic recreates this guy’s problem and shows how he fixed it.
At the end of the day, I think I will simply rebuild my meshes. I was working modular because I assumed it was the best practice, but I guess it depends on the context. That said, snapping my UV to a 64 grid is also a good bit of knowledge - I’ll certainly be using that workflow moving forward.
Modular is a good practice for sure but it can be difficult starting out without being aware of how to set some thing’s up for the best result. It’s a lot of trial and error in the beginning. Feel free to ask questions if you need help.
In those cases, it’s better to model the whole wall the way you want, since the meshes are so simple you don’t save anything by making them modular, in fact it would run worse because it’s a higher poly count and a higher number of draw calls.
If you’re working with an object with high poly counts or if you’re worried about the hard drive space that the game will take up then you would look into how much more you can reuse assets.
While that might be true for performance reasons, it does certainly help for map design to have “modular walls” that can be tiled and stretched more freely rather than building large, specific set-pieces for every length of wall you need (and no, BSP is not an especially viable alternative, since UE4 doesn’t really handle BSP very well).
For situations where you want versatility and variety, yes, modularity is great. What OP is doing is constructing every foot of the building out of small quads. If it was one solid wall that was modular, or several sizes of floor pieces, or one prefab chunk of a room, it is much more useful and less prone to errors.
It’s easier to make something exactly the length you want than to try and build it out of other components. There’s even tools for 3ds Max that can make it easy to move things you’ve made in there to UE4 while maintaining positioning and instances for the things that can be instanced.