I am trying to attach fog to some objects where it looks like the fog just hovers above the object and no where else. This way the empty space around the object (negative space) stays black and only the objects are lit, with fog just barely hovering above.

Basiclly I have some veins that I want to have fog to be attached around the vein but only enough to affect the area right above the vein.

If anyone can help it would be greatly appreciated!!! Thanks you're beautiful!
:roll:

ops:

Thats quite a broad question. Do you want to know how to make fog? or how to attach it?

Very simple answer: Try copying your geometry and slightly scaling it up. Then a apply a volume fog shader to the new geometry. Theres a nice selection of vex ones if you're rendering in mantra. Do you need fog? what about a transparent surface shader?

Good luck!