Thanks guys,
Great feedback, from everyone, I'm looking forward to working on this at the weekend.
I'm sure I'll be able to post one or two updates before I have to shift to incorporating the shot specifics and then I'm into NDA territory until the project is done.
Detailed self-shadowing in GI sounds like a great feature, I'll look forward to it, but I do understand why it's more of a long term goal.
Many thanks
Chris