Originally posted by fidhaakbar 2) i am trying to illuminate interior of a room with Physical sky and sun.. i kept an area light in the window and connected portal light shader to it and activated Final gather... i am not getting a good result... when i checked secondary bounce some light came.. but then also its not a good result... please help me.... You could try increasing the GI/FG scale in the render settings. The effect of that stuff is dependent on the size of your scene.