The problem seems to be exacerbated by the use of 'filter' versus
'transmit.' I didn't play with your scene enough to render a complete image
(it is your effort after all), but I can tell you that I believe this is the
way to go. Instead of using rgbf you might try rgbt. The fog doesn't help
either, so you may wish to add a transmit value to it, too.
Good luck!
Grim
