removing distortion from bitmapped drawings let s say you have a scanned image of a line drawing in this case a boat but it could be anything on the drawing you have a set of reference points whose true x y positions are known now you digitize the drawing manually in this case using yaron danon s excellent digitize program that is you use a program which converts cursor positions to x y and saves those values when you click the mouse upon digitizing you notice that the reference point values that come out of the digitizing process differ in small but significant ways from the known true values this is understandable because the scanned drawing is a reproduction of the original and there are successive sources of distortion such as differential expansion and contraction of paper errors introduced in the printing process scanner errors and what have you the errors are not uniform over the entire drawing so global adjustments such as stretching contracting uniformly over x or y or rotating the whole drawing are not satisfactory so the question is does any kind soul know of an algorithm for removing such distortion in particular if i have three sets of points reference x y the known true values distortedreference x y the same points with known errors distorteddata x y other points with unknown errors what function of reference and distorted could i apply to distorteddata to remove the errors i suspect the problem could be solved by treating the distorted reference points as resulting from the projection of a bumpy d surface solving for the surface and then flattening it to remove the errors in the other data points any kind and informed soul out there have any ideas or better yet pointers to treatments of the same or similar problems thanks earl
