[OSM-dev] Minutely Mapnik

Stephan Knauss osm at stephans-server.de
Fri Nov 19 09:45:40 GMT 2010


Hi,

On 18.11.2010 22:24, Frederik Ramm wrote:
> Martijn van Exel wrote:
>> Does the process of applying minutely updates only work when the
>> initial planet was a full planet, not an extract?
>> Is it possible to do this on extracts?
>
> Yes (use the bounding box filter on osm2pgsql), but there will be some
> fuzziness around the edges. I forgot what exactly it was, but there will
> be some cases where a node is moved from the inside to the outside or so
> where things foul up.

This is one point. It can be solved by using a slightly larger bounding 
box than required.

More annoying is that the ways and relation tables grow. This is due to 
missing checks for their geometry against the bounding box.
I still believe osm2pgsql can be extended to handle this. It will slow 
down the import as it needs to do additional checks.

I was too lazy to investigate this further. I run a cleanup from time to 
time to do the job.
I have the feeling the cleanup uses less resources than the overhead 
generated by checking the geometries on every update.

You can find the cleanup queries here:

http://wiki.openstreetmap.org/wiki/User:Stephankn/knowledgebase#Cleanup_of_ways_outside_the_bounding_box 


Stephan



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