They are arranged like walls in a maze and thus determine the players path through the forest segment. This is an example screenshot - Top View in Player Collision Visualization:
From the side they look like tree trunks (cylinders and pyramids with a high Z value):
And in game with lighting and foliage they work incredibly well and blend into the atmosphere while limiting the players path and hiding enough masked foliage in order to protect from overdraw:
I'm happy. They are however quite expensive polycount-wise .... each wall has upwards of 8000 polygons due to the minimum necessary complexity of each cylinder to create the illusion of a tree trunk. But with some decent LOD settings I should be able to tone that down as well.
This may seem like a small thing, but it is a huge step on the way to an effective and stable game performance.
