So i basicly unwrap a cube in blender, import it to Unreal Engine, add material, build, and get shadows on edges like so.
Mark seams, unwrap, and export as fbx (settings default since no matter what the results are the same)
Import to Unreal Engine (default settings), add material, and build everything
Get shadows on edges.
Can anyone explain to me what is going on? and how to fix it? since im really confused now.
Hi!
Lightmap uvs are not the same as material uvs… They are for storing light/shadow information so they should lay out differently!
The faces that have sharp edges and will have different lighting information should be separate with enough padding around them unless they will get “bleeds” from the other uv islands! This is why you have those artifacts on your cube!
Maybe you should search for lightmap uv tutorials…
below is a link to a recent livestream from epic that covers this topic (lightmaps and bleeding).
So basicly I couldn’t find anything usefull that touched on the basics of basics. Untill i stumbled upon this: Modular Modeling and Lightmapping Overview | Blender to UE4 - YouTube
and after unpacking light map you need to switch in Unreal Engine lightmap index back to 1, because it will make its own map on channel 2 and will point to it (that is if you will not mess with the settings).
And even after that youll still get some artifacts.
Now you have two choices:
either up the resolution of lightmap in Unreal Engine,
or you can go back to that lightmap in blender, select everything in it, and while pointing your mouse over lightmap hit CTRL+P this will pack your islands, and then you set margin on that to .150 (or something like that)
And now if you drag your cube into the world it should look and behave just like the basic cube from Unreal engine while still keeping lightmap resolution at 64.
Hope this helps to the beginners 
I think there are still some unclear areas for you…
If you set your own lightmaps in your 3d software you should turn off in Unreal to generate an extra one for them!
I think this is one of the best tutorials for beginners:
Glad you solved it your own way! 
…and this one is just right for you!
Could you post those two posts as a reply? so i could mark them as solution?
I’ll then reply with my own comment on my own testings and findings when i’ll make a video about it
I try! 
I think this is one of the best tutorials for beginners:
…and this one is just right for you! UDK - How to Fix Light and Shadow Lightmap Bleeding and Seams
So what i found out with testing and following this tutorial on this subject "Baked Lighting" and "Lightmaps" (Maya & Unreal Engine) - YouTube,
UnrealEngine4 + Blender - Lightmap Tutorial - YouTube this is the same thing but with blender. In blender you do not need to divide 1 by lightmap resolution. And if you’ll leave 4px of space between islands, it will give better results if quality (engine scalability) is set to low.
There are still issues with those lightmaps when trying to build modular walls like in L shape. But i guess it has to do with need to tweak lighting quality.
It is shame though that you need to go to supposedly outdated tutorial (it’s for UDK not UE4) to get the basics.
Thank you again for pointing me in the right direction.
