[Talk-GB] Ordnance Survey field boundaries etc. (moved from "Newbies")

Someoneelse lists at mail.atownsend.org.uk
Sat Mar 27 13:26:04 GMT 2010

Phil Monger wrote:
> The field boundaries on 25k maps are a derivative layer based on the 
> larger scale surveys - they come from data from as recently as 2009 and 
> not older than 2002. 

You're 'avin' a larf, surely?

 > Strictly speaking, a line on a 25k map is a "linear topographical
 > feature" and they implicitly state on the bottom that they should not 
 > be seen as field boundaries.

But if there's no "linear topographical feature" any more surely the 
line should not be there any more?

 > Having said that, it all depends on where you are. When I led
 > a geological project in the Mendips we found that the field
 > boundary lines were completely invaluable - only a couple were out
 > and it was clear why - wire fences! Nearly all were exactly
 > right.

My experience (primarily Derby, Notts, Staffordshire, Yorkshire) is that 
OS field boundaries (and the footpath overprint) simply aren't reliable 
enough.  It was primarily because of this that I'm here.

Even new data isn't always correct - the Pennine Bridleway in West 
Yorkshire is an example.  The OS seem to have taken a punt on a possible 
route before it got waymarked (or perhaps they just got it wrong), but 
either way, their map of that area is inaccurate.  OSM isn't perfect in 
that area - but it's mostly incomplete rather than inaccurate.

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