Before we configure the level for Enlighten, we need to create the Enlighten lightmap UVs. 

We could run a Enlighten precompute to do this, as in the tutorial See what Enlighten can do in Unreal. However, as we haven't configured this level to make best use of Enlighten yet, running a full precompute would take a long time. This is because the default configuration uses high-quality lightmaps and includes everything in the computation.

Instead, we'll run the Enlighten parameterize. This is a cut-down version of the Enlighten precompute which enables Enlighten visualizations and checks for errors.

1. From the Build menu, select Build Enlighten > Parameterize > All Levels.
   
   A notification shows that the Enlighten precompute is running.
   
   Another notification reports that the Enlighten precompute had errors.
   

2. Click Show Message Log to open the Message Log and investigate the error.
   

   To open the the Enlighten Errors log at any time, select Window > Developer Tools > Message Log, then select Enlighten Errors.

   

   The log reports a problem that stopped the precompute: "BP_Sky_Sphere requires an extreme number of Enlighten Lightmap Pixels. Either reduce the Enlighten Quality or change the Enlighten Lighting Mode for this mesh."
   The error occurs because the actor BP_Sky_Sphere is very large. If it were included in the Enlighten computation, it would use too many lightmap pixels.

3. Click the BP_Sky_Sphere link to select the actor that caused the error.
   
4. Close the Message Log.
5. To fix the error, exclude the actor from the Enlighten computation. To do this, in the Details panel, select the actor Sky Sphere Mesh (inherited).
   
6. Under Enlighten, under Set Actor Lighting Mode, choose Disabled.
   
   This excludes the actor from Enlighten computations. This is useful for actors in your level that you don't need to light with Enlighten.

7. Under Build, select Re-run Enlighten Parameterize to run the Enlighten Parameterize again.
   

   The Re-run option in the Build menu reruns the last Enlighten operation.

   The GeoPrecompMonitor window opens to show the precompute progress.
   

   If Incredibuild is already installed, the Incredibuild monitor window opens instead. 

   A notification shows that the Enlighten precompute is running.
   
   You can still use the editor while the precompute runs.

8. When the precompute is finished, it is applied automatically after 10 seconds. Alternatively, click Apply Now.
   

Next

• 3. Understand lightmap efficiency