ボリュームレンダリング

http://oshiro.bpe.es.osaka-u.ac.jp/people/staff/imura/products/VolumeRenderer

http://www.linderdaum.com/home/index.php?title=Main_Page
http://www.gamedev.net/community/forums/topic.asp?topic_id=527295
http://www.gamedev.net/community/forums/topic.asp?topic_id=530876