You can further reduce the number of lightmap pixels by having meshes share lightmaps of nearby surfaces, such as walls or floors. This mode is called Detail lighting in the Enlighten properties.

For the best results with the default lightmap pixel size, the entirety of the mesh should be within one meter of the surface. This means that the lampposts, for example, aren't good for sharing, as they extend some distance from the ground. However, the posters are ideal, because they're flat against the wall.

1.  In the Outliner, double-click the actor Props_Poster2 to focus on it.
   
   
   By default, this actor is lit by a lightmap. We can see this in the Details panel under Enlighten > Lighting Mode.
   
2. In the Details panel, under Enlighten > Set Asset Lighting Mode, select Detail to change the lighting mode for all actors that use this mesh.
   
   Detail mode means this actor shares a lightmap. Enlighten automatically chooses the best lightmap to share.
3. In the View Mode menu, choose Enlighten > Lighting Mode to see which lighting modes the objects use.
   
   Actors that share lightmaps with other actors, such as the posters, are blue.
   
4. The following actor uses a small static mesh asset always placed against walls, that would be best lit with Detail lighting mode:
   • Buildings_Wall_Pillar9

   Using Details > Enlighten > Set Asset Lighting Mode, set the Detail lighting mode for this actor. This change affects all the actors which use these static mesh assets.

   

   Before changing asset lighting mode	After

5. From the View Mode menu, select Unlit to turn off the visualisation.
6. To see the effect that this change has on the lightmap UVs, select Build > Re-run Enlighten Parameterize to regenerate the Enlighten lightmap UVs.
   
7. In the Outliner, double-click the actor Props_Poster2 to focus on it again.
   
8. In the View Mode menu, enable Enlighten > Lightmap Charts.
   
   
   The posters have the same color as the charts of the wall behind. This shows they share the same area of the lightmap.

9. Move the actor Props_Poster2. Notice that the lightmap UVs for the poster update automatically to match the position.

   Before moving poster	After

10. Put the view back to normal with View Mode > Unlit