Also don'r forget the haze (Maya fog) that almost always
comes with jungles and forests. Study the live plate,
and take cues from it that you can use in your CG lighting.
The prior suggestion of the foliage image in your light's
color attribute is great, and should help get you closer to
reality. If you really want to be anal about it, create some
paint effects trees (they don't have to have any lighting
on them, just make them fully luminousl)
and render out an
animation of them blowing in the wind. Be sure to fill the
screen with the foliage, and get many overlapping layers of
trees on screen. This sequence of animated frames could
then be used in the same way that the prious poster was
suggesting, except this would be moving slightly, and
may really up the believability factor. Remember to invert the
color of the sequence, or else you'll get the wrong results.
Good luck!
-Perry Harovas
the LIGHTHOUSE
Visual Effects, Post and Animation
617-491-3060
Boston, MA