Exponential Terrain Fog

can anyone explain the Exponential 1 or Exponential 2 terrain fog?

i think iv gotten it to work, but the editor seems to limit this...
from what i know, Z Start and Z End don't matter;
only the Density and Color matter.
and the only way you are going to see anything of your terrain, besides the terrain fog Color, is if you put the density as low as possible (.01), or something really low, and move the camera VERY close to the ground.

but who has the camera right above the ground?
it seems that if you could set the Density to something like 0.0001, it would work very well;
but blizzard reals can't be between 0.01 and 0!

so is there a way to set the density between 0.01 and 0?
or has someone found another way to make this useful, besides just having black terrain or something like that?

Z start and Z end matter enormously. They control the 0-100% ratio of fog. Z is the "vertical" direction on the map. So say you have Z start at 0 and Z end at 500, the density at 0 will obviously be 0, but the density at 500 will be 100% of your chosen density. So unless the camera is touching the ground, you wont see much.

Alos Z start and Z end control the distance where the fog starts. Try setting them to larger numbers (z end must always be larger)

Keep the density around the default... then once you have your idstance settings right set the density.