Ve-ry nice !!! One little flaw : the red light casts light on the wall because it's a glowing object . Glowing object always cast light with GI, they call this an area light . If you don't want this light on your wall, you can achieve the same glowing effect for the traffic red light by placing a multiplier in the color, with your red in source1 and a scale function in source2 . I can post a screenshot if you want . Overall, great stuff ! :)