[OSM-talk] Coastline updates

[Christoph Hormann]

On Friday 22 November 2013, Paul Norman wrote:
>
> A particular square (400x400 mercator km, I think) containing
> coastline can be evaluated without considering the rest of the
> continent thanks to the directionality of coastline ways mattering.
> You'd periodically get squares that would end up incorrect, but it
> wouldn't generally cause incorrect results
> outside that square.

I suggested something similar some time ago - processing in tiles would 
allow partial updates of the valid areas and the invalid tiles would 
simply be left in the previous state.  Given the dynamics of the errors 
in the OSM inspector this would probably not cause any of the tiles to 
get overly old due to persistent errors.

This is however not trivial to implement, it would not produce full 
unsplit polygons (which are sometimes needed - not for normal rendering 
though) and it would occasionally lead to small artefacts at the tile 
boundaries when one tile is changed and the other tile is not.

-- 
Christoph Hormann
http://www.imagico.de/