Ground[]
Ground, is basically either grass or concrete color. It does not hinder movement in any way and is just aesthetically pleasing.
Obstructions[]
This is a very common obstruction. It is a concrete fence with barbed wire on top. You cannot cross it or fire over it even when you are on a higher level.
This is a dirt wall. You cannot fire onto people who are standing on the level up the dirt mound, but they can fire onto you. It is dangerous for you to be below level of a Heavy Firepower class, as you cannot return fire.
This is a crate, and it is an immobile object which cannot be walked on, walked through or fired through, unless on an upper level during which you can fire over it.
This is barbed wire. You can fire over it but you cannot walk through it.