What do you think of this billboard ad?

I do not have a picture, but it is easy to describe. A carpet company has an advertisement talking about the cost it charges to carpet a room. Part of the billboard has a rectangle inside another rectangle, with dimensions labeled. I think the dimensions are something like 15 feet and 18 feet.

My first reaction was to wonder whether the dimensions were actual size. I figured that the depicted sizes must be too small. Then I compared the size of the rectangle to the size of the billboard and looked up billboard sizes. I found that billboards range in size from 14 by 48 feet to 20 by 60 feet. Now I am convinced that the dimensions are the actual size. I imagined an entire room projected on the billboard, furniture and all. It just seemed too weird.

Did my imagination go overboard? Is this an effective advertising technique. It certainly gets my attention, although I can’t tell you the name of the company.