Light from the sky

When your level contains a Sky Light actor which is Stationary or Movable, Enlighten provides both direct and indirect sky lighting.

Separate sky bounced lighting

By default Enlighten combines direct and indirect sky lighting which can look flat in outdoor areas when lit by sky lighting from above along with sun bounce from below. To prevent this, Enlighten provides the option to use separate sky bounced lighting for a small additional runtime cost. 

The images below show combined sky and bounce on the left, and separate sky and bounce on the right.

The cliff wall is mostly indirectly lit. There is strong sunlight bounce from below, and strong sky lighting from above. With combined sky and bounce the cliff appears lit from no specific direction. The cliff wall appears to glow in an unnatural way. With separate sky and bounce the cliff appears brightly lit from below by yellow bounce from the sun, and also brightly lit from above by blue sky.

To apply sky lighting separately from bounce, set r.Enlighten.SeparateSky=1 in DefaultEngine.ini.