Yes, and when I ran the mask it removed a lot of trees to each side cosmetically. I think I started using the smallest brush to draw grass along the road path before running mask. Still, I've been wrong about terrain functions since I'm elbow deep in a terrain right now and everything is blurring together.
I'll do a quick test, lay in a few miles of solid trees, lay down a cosmetic road and run the mask. I'll report the results back here.
Wish the river object could have it's elevation set to place the water sheet closer to the ground. It looks weird in testing while driving a tank on the river bank 6ft above the surrounding ground.....
Still I'm guessing you did that to eliminate that Z-fighting that happens with those water object squares that you lay them down over a hole and cover the edges. Until you are about 1000yds away, the water object rapidly morphs and conflicts with the ground covering it's edges. I setup a lake and ran a river path out of it as a test, the water object square is not ready for prime time.
OK, quick test time, I'll be back with results.