First way to look at it is physics. Fog absorbs and diffuses light; the fall-off of a point source will be faster, but the shadows will be very diffuse; light will be coming back from the fog itself to light up shadow areas. But other way to look at it is to take some dramatic license. When I light a scene like this in theater I break it up into Practicals, Motivators, and General Area light (which in this case would be mostly Backlight and Fill). The Practical is the lamp itself. On a 40' stage a 60w floor lamp with shade won't cast enough light to notice. Worse yet, that little bright spot of bulb will be very distracting to the audience. So we tend to put these on dimmers and turn them way down. In 3D terms, that means setting a glow channel on the object. The Motivators are theatrical instruments hung and focused to immitate the light that would be coming from that practical. That would be in 3d the lights we stick up near the thing that looks like it lights up. The thing to remember is that they don't HAVE to be in exactly the same position. A little artistic license can go a long way. In my Ninja pic the "moonlight" is coming from a point higher on the sky than the visible moon. In my "shoujo cop" pic here, the light bar didn't quite hit the character right so I re-inforced it with some little spots just a foot away from her body. Fill, wash, base light....depending on how you set it up, these are lights that just generally fill in the scene a little. This is particularly important in Ray Tracing where the real-world effects of radiosity do not take place. Back light is the secret weapon. The use of strong backlight in night scenes has long been a Hollywood cliche. The trouble is, it works. Backlight can seperate and define the figures in the scene, and even seperate and define the image planes making for a better sense of depth. Last, and not mentioned earlier, is a little bit of Specials on the things you really want to see, regardless of where they are in relation to the visible light sources. You can always pretend they are the light from another lamp just out of sight or a bit of moonlight through a thin patch in the fog. Nice image BTW. Just 'cause I tend to go dramatic myself doesn't mean I don't like what you did!