How to Fix Lightmap Bleeding: Part One | Tips & Tricks | Unreal Engine
In the first of this two-part Unreal Tips & Tricks tutorial, we'll demonstrate the different steps to solve light bleeding and get the best lighting results in Unreal Engine. We'll be using Revit to show you how to correctly prepare your assets before exporting your data in order to avoid any light baking issues.
For additional help, see the documentation:
Lightmass Portals: https://docs.unrealengine.com/en-US/Engine/Rendering/LightingAndShadows/LightmassPortals/index.html
Lightmap Density view mode: https://docs.unrealengine.com/en-US/Engine/UI/LevelEditor/Viewports/ViewModes/index.html#lightmapdensity
Settings for Lightmass (This also covers Lightmass Importance Volume mentioned at the beginning of the video): https://docs.unrealengine.com/en-US/Engine/Rendering/LightingAndShadows/Lightmass/index.html#lightmasssettings