Lightmaps and huge areas

hey guys,
I’m wondering how to handle large scenes like a big hall when using light maps? Let’s take for example my picture below. On the picture we have a lot of straight walls and floors which can’t be splited up so the only possibility for good looking shadows
would be a gigantic lightmap resolution which will eat up a lot of rendering time and also VRAM. So i’m really wondering what is the best way to handle such a scene with lightmaps ?

6afdca880e8cd7d13c87c9b90272055c431ad3b7.jpeg

If it’s a simple planar wall and floor, feel free to use BSP for that. It allows you to use “Unreal Units per texel” definition for the lightmap res (lower number -> higher res). Sure there will be splits in the lightmap when the engine packs them into atlases, but usually they aren’t noticeable. Also if you don’t need sharp shadows just lower the resolution.

BSP is sadly not really an option for me, actually im also looking for sharp and good looking shadows. Usually it’s not a problem for me to handle lightmaps for rooms, assets etc…
But a really large hall is something new to me and i can’t figure out how to work with it, having good looking shadow maps but also beeing efficient seems to be inpossible. Especially this big areas
like walls and floors are giving me a hard time, the only way to handle them is to set the resolution crazy high which is not really a solution. Here is the point where im starting to believe i reached the limitations of light maps / lightmass.

I know that Hourences explains how he approaches this problems. Basically split the room into smaller elements and adjust lightmap resolution for each element to small values, especially where the lightning is the same accros the whole element. He uses resolution down to 2 I think. Then, where the light transition appears, manually increase the lightmap resolution to get dark to light transition correctly. I am unsure if this is helpful:)

Also, his levels are a few GBs files so I guess this technique works: he bakes the complete level in one pass, probably on a really beefy (= a lot of RAM) machine.

Actually i dont care about the building time, the problem i have is when spliting up large areas into smaller peaces you get this ugly seems, especially on white walls or flors.
So spliting up may work for some areas but not for all… do you have a link where he explains his workflow ?

If you can’t split it up then you can try using a higher resolution lightmap, there’s not really a huge difference in using one really large lightmap and a bunch of smaller ones that amount to the same resolution. It is possible though that you can end up with not enough detail even at the highest lightmap resolution.

Thats my main problem, i would need for the floor and some other parts at least a lightmap resolution of 8K, which is not really efficient, on top of that my vram usage would be over the top…
I’m wondering if someone has made any experience in using this nice plugin… Granite SDK | Graphine | Texture streaming and compression middleware ?