Tree guards? Where's the software? And, for the third time, since my Opera crashed two times when sending this: the best modeller is probably Onyx Tree Pro at http://www.onyxtree.com/ It's also the most expensive at $495. No demo version available. There's also XFrog at http://www.xfrogdownloads.com/ It costs $199 for just the modeller, XFrog Lite, without animation capabilities. Finally, there's TreeDruid at http://www.zenstar.com/index.htm The price is $99.95. The disadvantage of the latter two is that they create obviously artificial trees. Especially so in the case of XFrog, where you can always see that the trunk is an elongated cone. The disadvantage of Onyx Tree is obvious, I think. :-) You might want to try L-System at http://www.geocities.com/tperz/L4Home.htm It's free, but I never tried it. There's also TreeGenerator, a shareware program at http://membres.lycos.fr/treegenerator/ The problem is, the author lost the source code and it's doubtful whether the development will continue. And it's not very good. Complex trees have humongous file sizes, and the polygons were unconnected. No amount of smoothing and unsmoothing couldn't get them to flow together in Bryce. I think there's more, but I can't think of them.

-- erlik