exterior : 
x,z in (-20..+20) visual horizon
x,z in (-10..+10) actual drawing


x=10                                                                 x=-10
----------------------------- z=+10 --------------------------------------
					|
					|
		M			|
					|
					|
----------E----|(5.2,5.0)

		   E@(7,5)
											Z+
											|
											|
z=0						X+_________(0,0).-------------------------------------
												|
												|
												|
                                    |
												|
												|
												|
												|					C
												|
												|
												|
												|
---------------------------- z=-10 ------------------E--------------------
x=10                                                                 x=-10


