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The depth (and other sizes) displayed in import furniture wizard comes directly from the OBJ file, and therefore from the sizes you used in Art Of Illusion. I added the ability to change the size of a model in the import wizard because most imported models haven't a realistic size.
Most models I designed have the same problem, but their size is set in a property file like this one : http://sweethome3d.cvs.sourceforge.net/sweethome3d/SweetHome3D/src/com/eteks/sweethome3d/io/DefaultFurnitureCatalog.properties?view=markup