I have now all hours in blender with 64x64 unwrapt and in UE4 due to the reference lightmaps created new in 512x512. But it looks worse than before. Some cover up as if they were hovering. Light comes through dark corners. These lightmaps in UE4 are really an impertinence. For weeks I have been doing many hours in meticulous work these lightmaps in blender. the best results I had when I in blender from the beginning of a resolution of 512x512 voted. If you tell me how I upload the fbx file uploade I will upload it. Anything basic I misunderstand. The videos leave nothing. they are all in English, and everyone seems to be doing it differently. Watch 10 different videos and you will find at least 5 different approaches. The only one that makes good videos in german, builds the geometry in the UE4. Partially, I have good results, but I do not get some weaknesses away.
