[OSM-dev] Turning boundaries to linestrings

Christoph Hormann chris_hormann at gmx.de
Tue Dec 13 12:33:29 UTC 2016

On Tuesday 13 December 2016, Paul Norman wrote:
> Feedback from anyone interested in using this output is welcome, as
> well as any additional information that should be added to the
> linestrings.

You have some conflicting goals here - you want to maintain the OSM 
tagging information on the way level so you need to maintain the 
individual ways - which however limits what you can do in terms of 
rendering - dashing is not consistent for example where a boundary is 
split and you have problems doing geometry processing (like the all 
popular ST_Simplify()).

IMO a process that merges the ways where it is non-ambiguous would be 
more useful.  And most cases where tagging varies in an admin boundary 
without there being a junction that is a tagging error.

The maritime attribute based on tagging is currently of very limited use 
since it is not consistently applied.  On admin_level 2 a better way 
would be to classify this based on topology - i.e. all boundaries that 
are only part of one admin_level 2 relation are maritime boundaries.  
On the higher admin levels this is more complicated of course and not 
easy to solve.

Christoph Hormann

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