procrustes-distance-is-sqrt-of-ssd

Summary

The Procrustes distance is measured in the same physical units as the original landmark coordinates (e.g., millimeters), because it takes the square root of the sum of squared differences. This matters because anyone reporting or comparing shape differences must use the square-rooted value, not the raw sum of squares, or the numbers will be in squared units and incomparable to actual physical distances.