[OSM-talk] Mapnik tileset coherency issues

[Steve Chilton]

That may be the theory but is not what happens.
Look at:
http://www.openstreetmap.org/?lat=51.52359029027119&lon=-0.15078493448827193&zoom=16&layers=B0F
I have re-aligned the Bakerloo Line tube between Baker Street and Regents Park, which shows correctly from the planet of yesterday at z16 and above.
If you zoom in to z17 it is incomplete, and if you zoom in to z18 it is completely as was. Are levels 17 and 18 special cases because of the numbers of tiles there are maybe though?

Cheers
STEVE

Steve Chilton, Learning Support Fellow
Learning and Technical Support Unit Manager
School of Health and Social Sciences
Middlesex University
phone/fax: 020 8411 5355
email: steve8 at mdx.ac.uk

Chair of the Society of Cartographers: http://www.soc.org.uk/

SoC conference 2007:
http://www.port.ac.uk/special/soc/

Mind the (Map) Gap:
http://news.bbc.co.uk/1/hi/magazine/5413010.stm



-----Original Message-----
From: talk-bounces at openstreetmap.org [mailto:talk-bounces at openstreetmap.org] On Behalf Of Frederik Ramm
Sent: 18 October 2007 14:02
To: Patrick Weber
Cc: OSM-Talk Openstreetmap
Subject: Re: [OSM-talk] Mapnik tileset coherency issues

Hi,

> What I mean is, say a tile x,y,z is dirty and needs to be  
> rerendered. You would include adjacent tiles on a given z , but  
> also on lower z levels (say a dirty tile x,y at zoom level 12,  
> would also mean all tiles contained by tile x,y at subsequent zoom  
> levels 13,14 ... would be considered dirty in the same job). Could  
> you render this batch of tiles than into a cache, before committing  
> the whole batch to the live tileset, thus ensuring more consistency ?

My understanding is that mapnik is so fast at rendering tiles that  
rendering a whole tileset (level 12 and everything below it) could be  
done in a time short enough as to not require any extra "buffering";  
the inconsistent state would probably only exist for a few minutes.

Bye
Frederik

-- 
Frederik Ramm  ##  eMail frederik at remote.org  ##  N49°00.09' E008°23.33'



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