Attached Link: http://www.renderosity.com/mod/forumpro/showthread.php?message_id=2741994&ebot_calc_page#message_2741994

bill posted sub caustics method in 2006.  as usual, find by searching poser forum, username bagginsbill.  inverse square falloff plugged into volume colour/density channel is more recent addition to his earlier technique**. ** whilst carrara can calculate wave-generated caustics quickly, mark bremmer (carrara expert) recommended method similar to bill's. ** **