area calculation

[Sjoerd W. Bijleveld]

I have an .emf file imported as picture in MetaDraw. This picture represents a certain urban area plan. With MetaDraw I'm drawing Lines, Polygons and Rectangles on top of this picture. I need to convert the length or area of these objects to real world dimensions. I have studied in the help file the MetaDraw Coordinate System (in the Concepts part) and Initializing a New Image / Setting Active Drawing Size (in the Basic Programming Techniques / How To part), but this has me highly confused! Basically, to get me started, I need the length of an line drawn with MetaDraw and then an conversion formula to convert the length of this line to real world length. Any help very much appreciated!