My brief look into how the tree above worked in game showed that it didn't seem to be blocking LOS at the trunk. This was a very quick test, though. I would like these to add a realistic amount of cover as well as being a visual change.
Remember .... Objects don't block LOS, they degrade the LOS by so many sighting factors based on the terrain type the ray crosses.
As an example, I'll go through a basic calculation on a sight ray passing in 1 hit, over light woods, woods, and heavy woods.
An infantry unit has 40 sighting factors (875m). The sighting rays (upper and lower) pass through 1 hit of blockage in the following trerrain type :
1. Light woods .... -2 per-hit ... new factor = 38 (750m)
2. Woods ........... -10 per-hit .. new factor = 30 (350m)
3. Heavy Woods . -15 per-hit .. new factor = 25 (225m)
As you can see, one tree model (single flat plane) in heavy woods won't block LOS until after 225 meter's. So, if you had 3 vertical planes for a tree model sitting in heavy woods you would degrade the sighting factor down by 45 points, which = 0 or 27 meters.
Anyway, IMO .... The more vertical planes the better!
In the screenshot below, if we were an infantry squad viewing the scene below, you can see how the trees block LOS. I can't estimate the range but you guys get the idea .... .