Example – Vectors of Displacement

The image below shows the sample map overlaid with vectors of displacement. Each vector line starts at a point that was previously identified in the old map and ends at the position where the point would be if the old map were as accurate as the modern reference map. This endpoint results from an affine transformation between the two sets of points. Exceedingly long vectors in red are easily identifiable and indicate outliers that are due to gross positional errors in the map.

"Die Landschaft Basel und das Frickthal" by W. Haas, 1798, with vectors of displacement.