Well kind of faked, but it looks good.
I’m new to blender but thought you might find this interesting. I’ve been mucking around trying to get blender to render 3d volumes, over the past two weeks, instead of working. My first attempt used a 3d mesh of cubes (generated by python - my first ever script), however because blender couldn’t do any sort of volumetric fog this causes artefacts at certain angles.
To get the cloud I just use a clouds texture scaled big mixed with a sphere blend to get a spherical cloud. All procedural.
I tried many things to try and get this looking nice including some weird alpha mapping. But in the end I gave up. So I switched to using several parallel planes all pointing towards the camera. Which looks much nicer, but wont shadow correctly.
With a bit of work you can shadow it with only one light, creating shadow planes aligned to the light, using the same texture co-ordinates. This can look pretty awesome. I used this for my final render, check the blender file out.
Then I got bored with clouds and wanted to do some animated smoke. So I hacked some volumetric fluid dynamics code together. Then I made it into a blender texture so I could use it in my scenes. Each time the frame increases it calculates the fluid motion. This was my first attempt.
Which I later refined to this:
Pretty nice, huh? It looks even better in motion.
http://will.thimbleby.net/downloads/3dsmoke6.avi
Anyway I zipped up the blender file, the source code for the texture (& mac os x compiled .so file), the python script to generate the planes and a avi for your enjoyment.
http://will.thimbleby.net/downloads/3dsmoke.zip
Enjoy, make some pretty pictures, and let me know what you think.
-Will