Map Analyst

[keithamoss]

This could be worth plugging in.

http://www.mapanalyst.org/

MapAnalyst is a software application for the accuracy analysis of old maps. Its main purpose is to compute distortion grids and other types of visualizations that illustrate the geometrical accuracy and distortion of old maps.

MapAnalyst uses pairs of control points on an old map and on a new reference map. The control points are used to construct distortion grids, vectors of displacement, accuracy circles, and isolines of local scale and rotation. As a by-product, MapAnalyst also computes the old map's scale, rotation and statistical indicators.