I think I'm understanding your question and correct me If I'm wrong.
Your asking if when you go over a structure, your seeing from top to bottom like a box?
If that is it, the answer is no. What you are seeing is a 20 Deg. cone. It's like an inverted ice cream cone.
Let me show you at this site.
This is the best info I think you can get.
http://www.lowrance.com/tutorials/so...utorial_01.asp