I´m working on a scene where I have a light shining through an opening in a polygon surface (or actually many openings). But I have a problem...
Ordinary dmap shadows on the light fog makes the fog really grainy and ugly, nad when I try to use RayTraced shadows there is no fog at all..

Ok.. I managed to make the dmap fog a bit less grainy by tweaking some settings (samples and suff), but it multiplied the render time by at least 10 times, so I´m really looking for a better way to do it.
I could use volumetric shapes, but it would take forever to make tem move correctly with the light moving past the holes in the wall.
The light is very sharp, sp the light fog needs to be quite dense to give it te right effect, and it@s when the fog gets denser the grainyness starts to apear.

Ok... What I really hope to do, is using raytracing, but as mentioned... no light fog! So if anyone could help me get my raytraced lightfog to work, It would be great!