To determine the boundaries of pieces of lands and then their lengths

Hello!! I am trying to determine the real lengths of boundaries of pieces of lands frm an aerial image.Having applied canny method to detect the boudaries, i then applied Hough transformation to detect the straight lines of the boundaries (Boundaries are assumed to be straight lines here).Distances were calculated also but the problem are 1. Not all boundaries were detected by the Hough Transformation.2.Calculated distances coul开发者_StackOverflow中文版d not be ascertained to any particular line on the image, because there are many lines defining the boundaries of the pieces of lands, so i dont know which measurement belongs to which line on the image. Pls assist.

If it is for a one-time calculation (and for a relatively small area) you might be better off digitizing the polygons manually and using a GIS package to calculate their lengths. Alternatively, if your lines are clean enough, you could convert them back to vector polygons; you may not get all the parcels, but at least then you have a way of calculating lengths and of attaching them to specific parcels of land.