The concave open picket fence is an elegant type of fence. The pickets
start tall and then as they shorten, the pickets concave slightly in
the middle. They can be assembled from prefabricated sections, where
the posts of each section are posted into the ground, but the pickets
or boards that make up the fence wall are not inserted into the ground.
Concave open picket fencing allows privacy, but still lets in light
and air, thus not exuding a feeling of closed off.