[OSM-talk] Mapnik coastline shapefile update - Philippine coast still somewhat square when exported

[Jon Burgess]

On Tue, 2009-03-03 at 13:41 +0800, D Tucny wrote:


> There's a large chunk of bad coastline around The Philippines that's
> been there since some shapefile update in the recent past...

I only updated the low zoom shapefiles last time. I just pushed an
updated set of low zoom ones too but that won't start rendering until
the weekly mapnik import finishes in a few hours.

> It can be seen here...
> http://www.openstreetmap.org/?lat=15.481&lon=120.274&zoom=9&layers=B000FTFT 
> 
> The coastline is all OK now (there were a couple of problems at one
> point) and the view at the coastline checker
> (http://tile.openstreetmap.nl/coastlines.html?lat=15.481&lon=120.274&zoom=9) and a local mapnik render I've done using the coastline checker output both show the coastline correctly...

OK, we'll see how things turn out tomorrow.

> A trac ticket was raised about this problem a couple of days ago now,
> but, I'd have expected an update of the shapefiles to have corrected
> this... It looks like it's only corrected the problem above zoom level
> 10 though suggesting that only the processed_p shapefiles have been
> updated...

Yes

> So... some questions...
> Is there a problem with the world boundaries shapefiles being used? 

No

> Were they generated from the processed_p shapefiles at some point?

They were derived from vmap0 data and we are slowly replacing them with
data derived solely from the planet.osm file.

I have just committed the changes into the mapnik osm.xml files so you
can see how they are used, I was holding back because there were some
occasional rendering issues, but I think these are resolved now.

>  Are the world boundaries files used on tile different to the ones
> packaged here
> http://tile.openstreetmap.org/world_boundaries-spherical.tgz? 

The ones on the live map are different.

> What would be involved in regenerating them? Once regenerated, could
> new ones be made available somewhere?

http://tile.openstreetmap.org/shoreline_300.tar.bz2

They are generated using the same coastcheck utility as is used for
processed_p but with some slightly different parameters and some data
simplification. The details are in:

http://lists.openstreetmap.org/pipermail/dev/2009-January/013485.html

Since I wrote that email I found that the RESOLUTION setting caused some
issues, the current values I use are:

#define RESOLUTION  0
#define TILE_OVERLAP  20000
#define MAX_SEGS  200

	Jon