If I'd have to mention one of the things that I see most of the time I fly helicopters, that would have to be the ground, as I crash a lot. The second would have to be trees (I also crash against them -- except inside cities; there I usually make huge holes on buildings). Trees are pretty much everywhere and, let's face it, they're not that pretty in FSX and P3D. Especially in FSX. ORBX decided to change that with their FTX Trees HD.