Greenscreen for "touchscreen tabletop" from below?
 

Hi!
I have to light a greenscreen on a table, simulating a touchscreen tabletop (like the one in the Control Room of MI-6 at Quantum of Solace).

5 actors will be around the table interacting with it. The greenscreen should be lit from below to have a nice and even lighting level.

Problem is that what happens with the "green" light (coming from below) that will cast all over the actors faces as they face the table? On shots where both the table and actors are seen, will the greenlight interfere with a good keying on post?

Also, I would like to use the lighting coming from the chroma as a "practical" so the actors are illuminated with light "coming from the screen". I was thinking about doing that with fluorescent tubes aligned around the borders of the table from below, next to the virtual screen.

My main problem is the interfering green-light coming from the greenscreen backlight... any help?

Thanks!
Luis

In my opinion, you're better off breaking this into two types of shots -- one where we see the actors' faces as they interact with the screen (but don't see the screen), and one where we see their hands touching the screen. "Faces" and "Hands."

For the Faces shots, use a big light table as a practical. For the Hands shots, throw a green gel inside the light table and do it normally as greenscreen.

There will be plenty of spill and wrap in the Hands shots, but that's easy enough to correct. You could actually use the backlit greenscreen as a practical for the Faces shots too, but correcting the green to white (which is very possible) will introduce some noise.

Alternately, you could ditch the greenscreen idea altogether, and just use the light table white. Then do a luma key on it, or simply roto the sequence.