UV Lightmap | Blender 3D to Unreal Engine 4

Why do I need Lightmap?

Lightmap UV is similar to a texture UV in that it consists of laid-out UV islands that are unique to each Static Mesh except this particular UV is used to store baked lighting and shadow information. 

When do I need Lightmap?

IMPORTANT: Lightmaps are only required when a Static Mesh will be lit using any form of baked or precomputed lighting. If your game or project is only using dynamic lighting, there is no need to set up lightmaps for each Static Mesh.

How to create new UV Lightmap in Blender 3D

  1. Go to Object Data
  2. Open tab UV Maps
  3. Add New UV Map
    • Rename from UVMap(x) to UV1
  4. Go to UV Editing
    • Change view mode to Edit Mode
    • Make sure mesh is selected.
    • Press A to toggle select all on/off.
  5. Press U on keyboard
  6. Select LightMap Pack
    • Keep default settings
    • Press OK

Unreal Engine 4 settings to import UV Lightmap

IMPORTANT: When importing objects from B3D to UE4 with custom UV Lighting Map is important to uncheck Generate Lightmap UV’s.

Setting the Lightmap Coordinate Index in UE4

The Lightmap Coordinate Index specifies which UV channel should be used for this Static Mesh when Lightmass generates a lightmap texture during a lighting build. Locate the Lightmap Coordinate Index in the General Settings section of the Static Mesh Editor.

SMEditor_LightmapCoordinateIndex.png

UE4 will attempt to assign the proper UV channel where possible when importing a Static Mesh that currently has a lightmap channel (UV Channel 1) or if a lightmap is generated during import. However, if you generate a Lightmap UV after import for a Static Mesh that did not already have one, you’ll need to manually assign the correct UV Channel to the Lightmap Coordinate Index.

Reference

Lastly edited: 08/05/2019