Modular Pieces and lightmass problems, what is the best way to go?

Hi Comunity!
as I have read [HERE][1] there is a known problem that exists with Lightmass problems and seams on modular pieces.
But I want to undestand more somethings about the problem and the best way to go to work around it. I hope this question can be very usefull for artists/designers new to UE world.

So, first of all, looking for some general and multipurpose asset to make some test (build some sketch… play with bluprints… etc…) i have created very basic geometries with just 6 quad faces (12 tris) for each asset. I also UVmapped the assets using one modular texture (with some floors, walls, and others tileable variations…) so I have one material-uvmapped that drive almost the entire scene… in it i have 1 normalmap and some grayscale/B/W maps to mask colors and also mask metals-non metals (so i have some metallic parts almos evrywere (just test…).
So that way i have (as know problem) bad lighting visualization:

example of piece:

3677-14.png

With more uniform lights ballance the result is better but the seams/difference of lightmass it’s always visible.
So I have started to study some Marketplace Demos Assets to see how the UE4 Pro are creating assets for…

In most cases (as suggested inf the other answerhub question) You need to try to hide some seams with others geometries, and you can find that way in the Shooter demo or avoid modularity at all as you can see in Realistic Rendering demo where the floor and the walls are “one pice”.

BUT in the Reflexion Subway Demo you find modular Floors and Walls! and they look very very good. So in this case (that is the most similar to what I want to archive) why the modular floor it’s looking so good? I also see that the main diference between my modular floor and the subway floor are:
1-subway floor mesh it’s flat (one face)
2-subway floor mesh have a dense topology (a lot of quads/tris) (my mesh floor it’s only one quad for each cubeface)
3-subway floor have a grunge and complex material/sader (my mat it’s simple and flat (just mask colors and metallic-nonMetallic separation).

so why in Subway demo you are using modular pieces and works very well? a lot of optimization/post effect?

thank u! :wink: