Hi, I really like art direction you’re going for here, it’s very clean and your visual language is very cohesive, I can clearly see a well planned theme with the environment as a whole- great job!
I’ll try to help you out as much as I can!
Light artifacts: (caused by baked lightmapping)
There are many reasons you get lighting artifacts like what you’re getting. The biggest problem I see here appears to be lightmap related. Make sure that your lightmap UVs on each static mesh is good. This is a really big topic, so I won’t go into detail. There’s some helpful info you can find with a Google search (surprisingly there isn’t as much “good” info on the topic as there should be); I’ve even made tutorials about it myself. Make sure your lightmap UVs are non-overlapping, they can stretch so don’t worry about some stretching here and there. Also make sure that your lightmap UVs aren’t fragmented, they should be as few shells as possible and as continuous as possible. The more splits you have, the more artifacts like these will be present when you bake lighting.
Also, when in Unreal Editor, hit the shortcut “Alt+0”- this will activate lightmapping view and allow you to see where your lightmap resolution is too low or too high. I often see a common mistake posted over and over on the forums; that you should crank up your lightmap resolution high and higher to remove these artifacts, by for example, changing all your static meshes to a resolution of 512, 1024, etc.- this is incorrect and you shouldn’t do this. Doing this will not fix the issue, just makes it less visible, and increases your build time through the roof- while also eating up your entire memory budget. Use that lightmap debug view to see where you’re going wrong/right with your lightmap resolution on your entire level. Try to keep your lightmaps in the green as much as possible; if you see blue then those objects have too little resolution- if you see red, then you’re cranking your resolution too high and need to pull it back.
understanding and having a deep technical knowledge of lightmapping and offline biased rendering will help understand why you get lots of lightmapping artifacts. Lightmass is an offline renderer that uses a lot of the same math and algorithms to mimic real world lighting that other industry standard renderers use, such as VRay, mental ray, etc. I will admit that there is very little information on Lightmass out there; the best source of info is the engine source code, but you already have to have an advanced knowledge on the topic to understand what you’re seeing in the header file in the first place. The default settings, I’ve found, are not setup to give the best results that Lightmass is capable of and I hope this is changed in the future. There are also some settings not exposed to Unreal Editor’s UI that probably should be, making even more difficult for most people to get “perfect” renders. I suggest you (only after fixing the lightmap UV problems on your static meshes) try turning down your “Static Lighting Level Scale”, and turn up your “Indirect Lighting Quality”, This alone will give you improved results; it’s really about tuning Lightmass correctly for your specific environment. I use different settings for every environment I work on- it’s the same concept when working on visualizations with something like VRay or mental ray; your render settings will be different for each job/project.
Shadow Distance Artifacts:
Based on the screen shot I saw you posted, looks like this is an easy one. Looks like your directional light’s cascade shadow map distance is too short. I find that it’s very short by default, so you may want to crank that up until it works best for your environment. Again, this is one of those things that you’ll need to adjust on a per environment/project level.
Anyways, hope all that technical mumbo jumbo helps, your stuff is looking great and can’t wait to see a quality lighting pass completed on this environment!