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?"
It'd be interesting to learn more about how this line was identified - was it by eye, or is there some neat analysis that was (or could be) performed to find it?
This short film he mentions (of the previous "longest" line hike) is really a lot of fun:
https://www.youtube.com/watch?v=64wZHZSxCZM
Semi related: hiking across England in a straight line
https://youtube.com/playlist?list=PL_japiE6QKWrN8t0-oUKOoMGx...
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.
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?"
It'd be interesting to learn more about how this line was identified - was it by eye, or is there some neat analysis that was (or could be) performed to find it?
Part 2 goes into the methodology - it's some neat analysis!
http://www.statsmapsnpix.com/2023/04/the-longest-line-part-2...