gcr 9 days ago

What does “straight line” mean? It looks like the curvature of the earth could be significant at this scale.

Does it mean that the compass’s bearing never changes? That wouldn’t produce a perfect sphere chord though.

  • defrost 9 days ago

    In this context

    https://www.ordnancesurvey.co.uk/blog/gbs-longest-linear-wal...

    it means "ruler straight line on standard UK ordance survey map projection" ie. a straight line on a specifically parameterised Modified Transverse Mercator projection.

    I'll leave the fun of working backwards from that to the reader, fun adventures include "Do they use WGS84 or do they still use whatever reference ellipsoid was current in the UK just after the end of WWII?"