Apart from light bleeding I’ve been getting, an entire section of my level doesn’t seem to be affected by built lighting, where previously the lighting built fine apart from the light bleeds. Any way that I can fix this?
Built lighting (with bleeding)
Built lighting (with no effect)
Does anyone have an idea as to how this can be fixed?
Hi Icaraeus,
I can see from your world (scene) outliner that you’re using a time of day system which would not using any pre-computed baked lighting.
The light bleeds are a result of using dynamic lighting. It will work well within a range, but “bleed” like this at greater distances. You can adjust the Cascaded Shadow Map settings in your directional light source for better results. You can read about some of this on our Wiki Lighting Troubleshooting guide (linked in my signature).
Also, looking at your world outliner it looks like you have ~6 copies of the BP_SkySphere. You really only need one of these. 
I got rid of the 5 extra copies of the SkySphere (I have no idea how I ended up with that many). Some parts of my level do use some sort of static lighting - I’m not sure how that’s the case since I do have a Time of Day system that kind of works. I adjusted the shadow map settings but nothing really changed in terms of light bleeds. These are my settings:
Also, the entire section of my level I linked still isn’t being properly lit.
Do you have multiple lights in your level? If so it may be that there are some set to stationary or static that need to be set to movable.
With the linked images, you may want to make your walls thicker or adjust the Shadow Bias to a lower value. This can produce artifacts though so it’s best not to go too low.
Long view distances will not work especially well with CSM without adjust some settings, thicker walls, or alternative methods like using distance fields.
In 4.8 there will be an option to use Far Cascaded Shadow maps where some objects can be tagged with the flag to use this method. This will allow these objects to have dynamic shadows at greater distances than the 20k units that is the hard limit for the directional light.
The only thing I have is a Lightmass Importance Volume, default Atmospheric Fog, one Directional Light and a Skylight. Adjusting wall thickness doesn’t seem to do anything.
Should I just wait until v4.8?
I don’t think there is any reason to stop and wait for 4.8. Lighting a level takes a lot of work just as much as layout, meshing, or any other thing. Working within the bounds of the system is key to getting the results you want.
Those results can be achieved by adjusting some things that I mentioned. The far CSM is really meant for much larger worlds for distant shadows.
Using Directional Stationary lighting can give you some better results since it will use lightmaps and dynamic shadows. This can give you the darker shadows with no light bleed at distances while using fully dynamic shadows as you get closer.
Thanks, I’ll try that out and see what happens.