I'm plodding my way through Blender and Luxrender and all things good, generally.
There's a concept I want to present on top of a cloud, for several reasons. «Idea space» for one, simple but realistic light for another. So I have tried the Cloud Generator script in the later releases of Blender. Works fine in the Blender internal renderer but with my favourite Luxrender, oh that is worse.
The rendered results have ended up so far:
1) Foggy, square bounding box.
2) Completely black, but it still takes resources to render. I believe the sun (only light source) may have been inside the bounding box here, but perhaps a sun should work anyway.
3) Foggy, square bounding box again.
On one end, I see there are some hints in the Luxrender -> Exporter Manuals -> LuxBlend25 Render Settings, but I'm beginner enough to not understand much of it. On the other end, LuxBlend doesn't promise to support every Blender feature so I only hope so.
So far, I've just started the script with default settings, using a mesh cube, eventually a mesh icosphere to start it with.
(Even with an icosphere as starting point, the render ends up square. The size of the Cloudbounds box.
What can help? Perhaps make a particle system instead of the default? I'm really out in the fog here.