This is gonna make me crazy.
Parallax: http://postimg.org/image/6f1fwnlp3/
Steep Parallax: http://s7.postimg.org/dgzdiupay/background9.jpg
I heard about a bug on steep angle ( [Patch] Bug in Steep Parallax Mapping of Lighting shader ) but this is old and it seems to be fixed in the shader that i use…