Clay's volumetric fire. set the quality higher than normal and softer edges. 

at least thats how i remember it...

I wish I could help....   I normally use cubes with cloud textures in them....   sometimes that works...

nice scene idea....  UVDan

Attached Link: http://market.renderosity.com/mod/forumpro/showthread.php?message_id=2831136&ebot_calc_page#message_2831136

Above is same image as linked thread with a little post work. (blurred it around the edges a little mostly)

Attached Link: Local Job

mdb

don't know how you'd do it, but probably one thing that will help is dispersion; smoke starts out thick, then thins out with altitude.  Maybe that DTE thing where the angle affects the texture, but that's all beyond me.

Another idea maybe.  
Meta balls, spheres, cubes, etc.  tend to not do well when they over lap with volume mats.  Possibly experiment creating  a curved lattice shaped like a bent cone then mat it with volume smoke/cloud.  There would be no overlapping of objects that way.  I've never tried it.

Thanks for the suggestions everybody.  I will check them out.

Some volume textures cut outta each other where their objects intersect, others dont seem to do so as often. it's kinda hit and miss. I wonder if maybe some of AS's cloud materials can be adjusted for smoke effects?

Rayraz, that's so true.  it's why I try to stay away from them as much as possible.  And it doesn't seem to help to group them either. :c/  Mixing rock terrains, and spheres (stretched out into ovals and spun around randomly) can give some VERY realistic effects, if you can find the right combo.  I also notice you have to play with the "frequency" of the textures a lot as well to tune them, especially if it's a long distance off.

gives bunny a skritch behind his digital ear<

mdb

Grouping doesn't help, it's probably really just a problem in the way bryce's engine handles volumetrics. I've even tried instersecting the whole sphere formation with a large other object or such, but that doesnt help either.

I tried creating a lattice from a photoshop grey scale image.  It works, kinka.  It is tedious and hit and miss getting the volume mat to hold the desired shape without completely filling the lattice.  render times seemed unusually high.  So strike that idea fm the list.