Low fog is not very effective because the top of it is so flat and unrealistic - hence the need for the techniques described above. I was experimenting with using thick haze and/or fog indoors for having strange mist in a creepy dungeon. It doesn't work very well, because fog/mist seems to have an inflexible 100% ambience. So where I had a corridor receding into darkness, the fog would be glowing brightly in the distance.