iD.geo.euclideanDistance should only be used for calculations of
projected coordinates or display (pixel) coordinates.
iD.geo.sphericalDistance calculates approximate geographical
distances, accounting for distortions at higher latitudes. This
can be used for determining the nearest node (operations.Delete,
actions.Circularize) or relative length comparisons (actions.Split).
They need to be removed from any parent relations.
Also, make sure to uniq child nodes, otherwise the
start/end node over-contributes to the centroid
calculation.
This action needs tests.
