I am trying to generate a series of transformational formulas in Excel to rotate, resize, and otherwise distort map A to something that approximates the projection used in map B, at least close enough that they can then be superimposed on each other and traced by hand to copy the pertinent information. My destination map template is the Robinson projection
So far, I have a way to calculate first a rotation (measure the XY position on two identifiable points on each map, calculate the angle on each image, and rotate to correct for the difference), and then a resize factor (measure the XY length of a box that covers two identifiable points on each map, calculate the width and height of the box on each image, and resize accordingly; this may involve different vertical and horizontal factors).
However, I have realised that where the map is significantly removed from both the zero latitude or the zero longitude, there is an additional "shearing" distortion. Does anyone know how to calculate a correcting factor for this?