I’m sorry if this has been answered or otherwise covered already but I can’t seem to find anything in these forums explaining how to emulate light through leaves with vray.
fast sss works but obviously only if you don’t rely on opacity maps.
Does anybody have a clue what to do?
I have tried to use selfilluminated in order to lighten the local shadows but the effect isn’t that nice.
You could use a vray2sided material for this.
Best regards,
Vlado
vray2sided is very slow and way over the top for my needs.
It’s not for looking into the sun through the leaves but just to lighten up the foliage.
Making the leaves transparent also burdens the system, although to a lesser degree but it doesn’t look too good.
What I really could use was a material based shadow controller.
Something akin to Raytrace Shadow Override from blurbeta but compatible with vray off course.
Maybe this is possible with some function I’m not aware of.
Do a blend material with a vray light mat? There was a few really nice forest renders about a year ago and the guy that did them just used self illumination. why not just change over to geometry and use fast sss?
Using a falloff map, setting it to shadow/light might get you some of the way.
Hope it helps
Peter
will try the blend/light mat
and the shadow/light falloff map.
thanks for the suggestions 
The reason I’m not doing geometry is because I’m generating the trees through xfrog and xfrog doesn’t supply a way to use geometry leaves unless you want very simple shapes.
there was this script that converts opacity mapped leaves to geometry, though the link doesn’t work any more, mabey if you ask him nicely he might send it
http://www.chaosgroup.com/forum/phpBB2/viewtopic.php?t=14248&highlight=convert+leaves+geometry
Wow nice thing with the script I’m trying to pm him.
Thanks
If this works everything can be done 
The blend/light map is unclear to me, but the falloff works fine.