Step 4: Convert each .dig file to (longitude, latitude) coordinates
You can use my program Projector on any Windows computer. Projector will read a .dig file and produce: (a) a new .dig file with the same shapes in another coordinate system, and (b) an .ai (Adobe Illustrator) graphics file to display the results. Projector will give you an opportunity to describe the projection of the base map that you digitised from (type of projection, standard parallels [if appropriate], etc.). The "projection point" is any point on the map where there is no distortion: for a conic projection it would lie on a parallel mid-way between the standard parallels; for a Mercator projection it would lie on the standard parallel or meridian, etc. After you have specified the map type and projection point, you go on to describe your Cartesian (x, y) system by giving the coordinates of the projection point in the (x, y) system, and the azimuth of your +y axis at this point (relative to local North). Note that the 4 questions that refer to the "new .ai plot" are discussing an Adobe Illustrator plot that will be created by Projector, not one that already exists.
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