I know you've done a global illumination based on a complete sphere. In the cases where 'below ground' does not need to be illuminated, would it be an idea to develop a lighting scheme in the top half of the sphere? This would reduce the number of lights. It would also be interesting to compare the lighting from some existing freebie lighting setups to a 'global illumination' setup for a figure and/or scenes. If say, out of 5 different scenes, global illumination worked well enough (almost as good as an indivually hand tweaked lighting setup), it may be useful as a general lighting setup for newbies ... like me :-) But if global illumination turned out to be the worst lighting in every case then it might be best left as a learning exercise in programming in python! :-)