Mike, OK I played around with it a bit. For awhile, I couldn't get the effect at ALL. I must've fiddled for 30 minutes. Finally, I started playing with the mixing proportions slider -- that seemed to really make the difference. It must be a really tight "threshold" between deciding which material to use, at least with my sample terrain. Literally, the difference of 25% to 40% on the mixing proportions would cause one material to dominate almost 100%, if that makes any sense. Any chance you could email me your scene so I can play with it? I'd like to play with it in the context of your example... (brian@lonewolf.tierranet.com) Thanks for all your help, this has gotten my wheels churning! I like playing with the ballroom floor idea! Not only funny, but it really demonstrates the idea. Brian