litst, Nice wispy cloud! I've used that same approach in the glow channel of a mesh dome, and can see the advantages. However, I discovered a quirk of GI rendering when I've used big spheres surrounding a scene -- the photon intensity actually increases in the areas that should be deep in shadow. It is most noticable with objects that have deep recesses. The skydome approach avoided this problem. I'm not sure I'd want this bug completely removed, as it can create some startling effects. Here is an example, with the illumination in the glow channel and the surrounding sphere made invisible. The shapes are 2 macromolecules very close together. You can see that the light bounce (white source) gets more intense where it should be darker. I'm not sure if this effect owes to making the surrounding sphere invisible, but I wanted a way to avoid the problem if it does crop up with visible illuminating spheres. Would be nice to have this reversal as an option when needed. SMcQ