Baked Light on some objects wrong?

As you can see in those attached screenshots. There seems to be something wrong. A simple object like a ceilling which is just a quader is visible darker than the walls beneath it which share the same material. That one in the middle had the same problem but after a while it disappeared. No idea why.

As you can see UV Lightmap index is correct and also does the uv map look ok as far as I can tell. Anybody has an idea why that is?

Also the asphalt in front of the building is darker on object 2.

regards

Hi!

Are you sure there are no overlapping faces/meshes with the roof/ceiling?
Do I see it right that all your floors+ceilings are one mesh? I haven’t seen your lightmass settings but I assume you’re after archviz quality… You can’t set higher than 4096 resolution to your lightmaps… and for archviz you’ll need the most you can have: at least 1024 per floor…

It looks like you have some Z-fighting

Thanks for your time.

There are no overlapping faces at this position . All geometry is out of cad software and it is exactly built. I already tryed to move both object a bit more but it did not change anything.
Floors and ceilling are each one object. So it looks like this: Floor, Wall from Groundfloor, ceiling, Walls from First floor, Ceilling.

At the moment im using 512 for most lightmaps. So im gonna up that definitly. Thanks for the tipp.

Yes there is some Z-fighting but not at this position.

I kinda fixed it today by doing a uv map and flatten in max. The result of the uv map looks pretty much the same but doesnt produce this problem anymore.