For efficient Enlighten lighting, it's important to find a balance between lighting accuracy and cost.

If you specify a smaller lightmap pixel size for an actor, Enlighten produces more lightmap pixels for each chart. The Enlighten Quality of each static mesh actor defaults to High, which targets a lightmap pixel size of 100 units. This is a good level of accuracy for areas seen up close, but requires more lightmap pixels.

You can safely reduce the Enlighten Quality (thereby increasing the lightmap pixel size) for areas that are always seen from far away, such as the higher levels of the buildings. The reduced accuracy isn't obvious when viewed at a distance.

1. In the View Mode menu, choose Enlighten > Lighting Quality.
   
   

   
   This shows the Enlighten Quality assigned to the actors in the level.
   The Lighting Quality visualization colors meshes as follows:

   • Blue: High
   • Green: Medium
   • Orange: Low
   • Purple: Background
   • Gray: excluded from the radiosity computation.
   Currently, all the actors using lightmaps are colored blue, as they all use the High quality level.
   The size of the checkerboard pattern shows the radiosity resolution of the High quality level.
2. In the Outliner, select the actor EnlightenSystemContainer.
   
   The EnlightenSystemContainer actor contains properties that apply to all actors in the same level.
3. In the Details tab, under Enlighten Settings, set Default Quality to Medium.
   
   All the actors now use the Medium quality level, colored in green. The size of the checkerboard pattern shows the radiosity resolution of the Medium quality level.
   
4. Select any Static Mesh actor. In the Select menu, choose General > Select All StaticMeshActor(s).
   
   This selects every static mesh actor in the level.
   
5. Right-click on the selected actors and choose Visibility > Show Only Selected.
   
   This hides everything except static mesh actors. This will make the next steps easier.
6. Press Esc to deselect the actors.
7. Select all the street-level actors that use light maps, such as the ground and first-floor walls. These are the areas that the player sees up close.
   The fastest way to do this is to hold Ctrl, Shift and Alt and drag a selection box to add multiple actors to the selection.
   You don't need to be too precise when you do this. Use your own judgement about which actors are likely to be seen up close from the street level. 

8. With the static mesh actors at street level selected, under Details > Enlighten, set Enlighten Quality to High.
   
   
   
   The lightmap pixels for the actors using Medium are now larger than those of the actors using High. This means they use fewer Enlighten lightmap pixels.

   During this process, it's OK if you also change the Enlighten Quality of actors that don't use lightmaps, such as lampposts and trash bags (colored gray). As we changed these actors to not use lightmaps, it doesn't affect the result.
   It's also OK if you change the setting for the background buildings. We'll change these in the later steps.
9. As the background buildings are always seen from a distance, we can set them to Low.
   In the Outliner, hold Ctrl and select the three Buildings_Background meshes.
   
10. In the Details tab, under Enlighten, set Enlighten Quality to Low.
    
11. As the signs in our level emit light, we want them to have sufficient lighting accuracy.
    In the Outliner, select all the actors in the Assets > Signs folder.
    
12. Under Details > Enlighten, set the Enlighten Quality to High.
    
    
    Now the signs use the High setting, shown in blue.
13. Re-run Enlighten Parameterize to regenerate the Enlighten lightmap UVs.
    
    In the View Mode menu, choose Enlighten > Lightmap Charts to see that the signs now use more lightmap pixels than before, and the background actors use far fewer.
    

Next

7. Use Enlighten reflections