[OSM-dev] tiles tiles tiles

Christopher Schmidt crschmidt at metacarta.com
Thu Nov 30 02:58:22 GMT 2006


On Wed, Nov 29, 2006 at 11:55:33PM +0100, Rapha?l Jacquot wrote:
> Jon Burgess wrote:
> > On Wed, 2006-11-29 at 21:23 +0000, SteveC wrote:
> >> Using a bugfixed version of almiens tilecount.pl (which figures out what
> >> tiles actually have map data on them), I've written a script to render
> >> them (from zoom 0-18).
> > 
> > I believe there are a couple of edge cases which we may need to
> > consider. 
> > 
> > 1) Way segements which cross a tile even though the nodes are no nodes
> > inside, e.g.
> > 
> >    ------
> >   |      |
> > +-----------+
> >   |      |
> >    ------
> 
> this is handled by the postgis operators

But it's not handled by the tilecount.pl script, which is what Steve is
saying is going to be used to decide which tiles to render.

> > 2) Text labels and icons which extend beyond the edge of the tile containing the node 
> > 
> >  ------- -------
> > |       |       |
> > |   *City-Name  |
> > |       |       |
> >  ------- -------
> > 
> > Perhaps we need to ensure the 8 surrounding tiles of and on the list is also rendered.
> > In many cases these tiles will already have nodes so the overall increase in the number
> > of tiles to be rendered may not be as big as first appears.
> 
> if you look at the python program, it renders on a 512x512 tile and cuts 
> out the sides to keep a 256x256 center

Which still only works if you're going to render both the left and the
right tile, which wouldn't happen if you're only using tilecount.pl.

Regards,
-- 
Christopher Schmidt
MetaCarta




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