Increase the shadow contrast

Hi,
I’dl like to increase the contrast of my shadow.how to?
Precision : I can’t use a sky in GI cause : bug splat.
See the topic mentionned here :
http://www.asgvis.com/index.php?option=com_smf&Itemid=90&topic=2831.0

Here : render and opt.



Cheers. :wink: