Im having a major issue that i think is going to make me quit making games!! im a really skilled mapper!!! but ive recently found that when i rebuild my scene it looks horrible due to overlapping uvs and not having enough spacing between uvs,i use automatic uv in maya to get my uvs good enough and scale them out in ue4 for perfection. i was told to manually do this is my 3d modeling program and that seems nearly impossibly and time consuming and a waste of productivity! when i create my scene in ue4, the preview lighting as you import and place your meshes are PERFECT!! i dont see why i have to rebuild my lighting or why it dosent stay the same after light rebuild, my question is…is there a way or a setting that will allow me to keep the preview lighting before light rebuild!!! after i rebuild my lightning my scene is wrecked to the bone!!! and having to manually do all that stuff to fix each mesh seems utterly primitive and retarded…Please help me , I am contemplating shooting myself !!!
You’re most likely going to need to remap your models.
When you imported your model, I think if you generated Lightmap UVs, and had the “Destination Lighmap index” different from “Source Lightmap Index”, you should have decent light builds, if you set your Mesh’s light map resolution higher, and tweak your lightmass settings ?
Otherwise if it doesn’t work and for a less clean solution, if you don’t want to care about lightmaps at all, you can just “Force No Precomputed Lighting” (in your World settings), rebuild light to delete previous computed lightmaps, and put a directional light on Movable mode.
Hi!
If you like the look before you build light: that’s the dynamic lighting you see (as if your mesh was lit dynamically and not statically with the light build)! So if that’s good enough for you and you don’t need global illumination (because that comes only with static lighting) then just set all your lights/meshes to movable and you won’t need to bother with lightmaps and building lights! 
thank you guys for all your responses im going to test some of this stuff out im great full!!!