Does anyone know whether it's possible to turn off antialiasing on tree-lab trees? The normal method for other objects - Shift+Ctrl and click the tickmark in the attributes box - doesn't work. (Trees have no attributes box anyway, and if you do this from the tree's edit box it has no effect.) Many thanks

nope can't turn it off for trees or metaballs (which trees are derived from). The only way to do it is to do an object mask and composite the unantialiased tree into the scene. You don't have to make a different scene to do it. My "Refueling on Planet X" had the tentacles done this way.

Thanks for the advice, that has confirmed my suspicions. As the effect I want involves having very small, very high specularity bits of blossom mixed in with ordinary leaves (i.e. 2 trees superimposed) I think masking would be a bit difficult. I'll probably just put it in as post work.

It may not be all that difficult. Select both trees and go into solo mode now select the one tree that you want un-AA and do a render mask. Only those parts that can be seen will be white. It's what I did because the Aslan (in Refueling on Planet X) was in front of the tentacles. I took them both into solo mode then unselected the Aslan and rendered the mask, where his legs were in front of the tentacles showed as black. One note here, to do a object mask with metaballs that are grouped. You can't select the groups, the mask won't turn out right, you have to select just the metaballs.