I remember doing it, but now I forget how. Basically, I have a floor, and a tree (well, lots of trees). The bottoms of the trees are at the same height as the floor. ( actually, the floor is 0.003 above them. This is so it will recognize intersection. Then I can weld everything later). So, how do I make it so that it will fuse the tree to the floor, and delete the bottom of the tree under the floor?

The end result should be a all the trees connected to the floor, and the floor split up into a lot of polygons to accommodate the trees.

Also, please reply to this!!!!
http://forum.halomaps.org/index.cfm%3Fpage=topic&topicID=23871

Thank you!

make a duplicate of the tree. move it away from the original tree. click on the floor to select it. goto the 1st tab on the right panel. in the dropdown click compound objects. click boolean. then click the pick operand b button. click on the tree(s). this will make a perfect hole for ur trees. place the trees in the holes as exact as you can. attach the map to the trees. select all the verts in the map. go down to weld and set weld threshold to 4. click weld and you should be done. enjoy :)

Well, you could use Boolean, or BooleanPro, I'm not sure which..and just toy around with it, I'm not sure the specifics, or you could try the Weld tool or just move them into position and use the Attach tool and then just Tessalate at 0 till you can only select the stuff below the ground and delete that.

Or you could just leave 'em like that, since no one'll see the bottom anyway.

attach your trees to your map, then convert to editable poly, and target weld the verts until it is attached.