Using 4.12.5. Not really sure what’s happening, but inside of the “crypt” walls are dark, ceiling is dark, but floor is the same as outdoors (sand is static mesh):
No matter what I do, walls / ceiling react properly to the lighting, but floors don’t. I have directional light and sky light. Both are static.
Has anyone had similar issues?
Thanks
Added a blocker mesh to seal that “room” completely (also added a smaller room made from brushes and converted into static mesh). Note that the blocker, the ceiling and the floor are all static meshes, with exactly the same materials applied to them.
Bizarre… 
I gave up trying to get my bakes to look great, instead trying dynamic lighting wherever I can afford it. This scene looks small, maybe try dynamic?
Unfortunately I can’t use dynamic lighting - it’s for mobile VR
Hmm. Well, I think the issue is that the different meshes are baked in different threads and the floor is being computed WELL before the walls inside the crypt. Maybe try modularizing the floor a bit so this doesn’t happen and they compute closer to each other?
That doesn’t make sense. Lightmapping should be working like regular offline rendering (e.g. Blender’s Internal or Cycles, etc.) and if Lightmass doesn’t do that, how on Earth such half-a$$ed lightmapper exists in the top of the line game engine?!
I’ve worked with Quake 3 lightmapper since 2008 and never had issues with lighting any kind of scene (indoors, outdoors, mixed environments). It always came down to bake time and quality (splotches), but never to half of the geometry lit properly and half unlit (or like in this case, lit as if it’s still outdoors).
Maybe @RyanB or [MENTION=4894]Tim Hobson[/MENTION] could help ?
Thanks
“This is an unfortunate side-effect of how static indirect lighting is handled at the moment and doesn’t have an easy way to fix.”
That’s helpful 
I’ll try some of the tips listed there, but at this point I think I bet on a wrong horse going into mobile development.
[MENTION=4894]Tim Hobson[/MENTION]
It’s not about shading differences between modular pieces. Floor is a single static mesh. It’s about lightmapper ignoring 100% sealed off space and not calculating lighting properly for indoor areas located in the outdoor areas.
I agree, it doesn’t make sense. I’m dealing with exactly the same thing right now and that’s what I’ve surmised. Maybe I’m wrong, but it’s the only lead I have so far.
I guess UE4 wants everyone to use real-time lighting, effectively declaring that UE4 is for PC/consoles only and mobile/VR platform is a by-product.
Anyhow, I just thought of a hack I’ll try after I get off work. I am planning on placing a small point light with intensity set to 1 inside the room and re-build. That should force Lightmass to calculate insides of the room and hopefully it will be lit more or less properly (dark).
Also thinking about Lightmass Portals, but there isn’t whole a lot of info about that besides: What's New | Unreal Engine 5.3 Documentation
I agree, it’s really weird that this issue still exists. I can’t get around it. I even tried your “hack” and it still doesn’t work. 
Have you tried Lightmass Portals ?
So, is this something Epic can fix?
Weird sh#t is going on :mad:
I tweaked lightmap indices on “test room” mesh (since it was converted from BSP to static mesh) and got walls/ceiling getting proper lighting. However, the **** floor is not receiving it. WTF?!?!?! :mad: :mad: :mad:
Next thing I did was moving the test room away from the shadow area to the well lit area - same story.
Next step was raising the test room slightly above the sand. That got me proper lighting in the whole “test room”, including floors (not 100% dark, but much closer to what it should be).
Why is this happening, Epic devs?!
Does it meant UE4 is not designed to have mixed environments with purely static/baked lighting ?
P.S. Tried doing the same with the “crypt” and it didn’t do the trick. As if walls don’t block sky light at all. I’ll try removing sky light and see if anything changes at all.
“A Sky Light should be used instead of the Ambient Cubemap to represent the sky’s light, because Sky Lights support local shadowing, which prevents indoor areas from getting lit by the sky.”
I don’t believe the feature in bold is working (or maybe it does, but partially, since floor in the “room”/“crypt” isn’t being darkened).
Do you think you could try baking our mixed environment scene without Sky Light present ? (but with using indirect light in Directional Light)
@motorsep Just got dragged in from another thread. I don’t think that your issue is related to this.
Back around 4.6 or so I made an open scene with a cave, that had quite narrow and long entrance. It was static lighting only and I did not remember having any complications. It was a desktop project though. I remember only enabling cast shadows as two sided on terrain mesh and unchecking lower hemisphere is black in skylight. Otherwise, most settings were close to defaults.
I don’t see anywhere in my post I mention having seams between modular pieces. It has nothing to do with modularity and that link (which [MENTION=4894]Tim Hobson[/MENTION] also posted).
It has to do with floor receiving Sky Light (my latest theory at this time). I bet if I shrink the model of the floor to be enclosed inside the room, it will be lit properly. However since it sticks out (part of it inside the room, part outside), it ignores the indoor factor.
Another theory is that I need to enable two-sided lighting on the floor mesh (since it has no bottom).
Does the land mesh have high enough lightmap resolution? Your land mesh looks quite large. Also like two sided shadow I’ve mentioned before refers to dynamic shadows only it seems.