[OSM-dev] [Tilesathome] Proposal for T at H land/sea updates

Martijn van Oosterhout kleptog at gmail.com
Wed Jun 4 06:54:58 BST 2008


On Tue, Jun 3, 2008 at 5:37 AM, Alan Millar <am12 at bolis.com> wrote:
> I'd like to make a proposal for improving Tiles at Home.  Before anyone asks,
> yes, I am volunteering to code this.  I'm looking for clarification,
> feedback, or suggestions.

Thnaks for taking the time to think about this.

> There is a problem right now that some z12 tiles are built wrong.
> Sometimes a land tile is colored as sea, and vice versa.  (I am not
> talking about the "unknown type" tiles which will fix themselves over
> time).

I created the first version of oceantiles.png and it was basically the
output of my render script for the PGS data. The errors are primarly
of the form:

- coastline that was wrong in PGS obviously converted wrong and when
someone fixed the uploaded coastline you get a difference.
- oceantiles is misleading, since it also needs to register large
lakes, since they also need to be blue. Any lakes not in PGS are thus
wrong.
- People shifting the boundary between the sea and the river leading
to it. PGS was essentially computer generated and didn't know the
difference, but when OSM mappers shifted the boundary of the coastline
to near the coast it sometimes left a gaps of incorrect tiles.

Distribution of the data was a problem considered at the beginning but
never really solved. I'm glad you're thinking about it.

Have a nice day,
-- 
Martijn van Oosterhout <kleptog at gmail.com> http://svana.org/kleptog/




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