[OSM-dev] Detailed Coast display in Mapnik

[Shaun McDonald]

On 15 Aug 2007, at 06:00, Brent Easton wrote:

> Hi Cameron,
>
>> Mapnik uses only external data (world_boundaries.tar.bz2, linked  
>> to on
>> the wiki) to render coastlines - the stuff you draw in as
>> natural=coastline is ignored completely.  I'm not sure why the data
>> breaks when you zoom in some areas (such as Australia, but people  
>> have
>> also complained about it in other countries).
>
> ?????
>
> There must be more too it than that.
>
> Have a look at this area around Plymouth UK:
>
> http://www.openstreetmap.org/? 
> lat=50.34800311344643&lon=-4.151113641491551&zoom=12&layers=B0F
>
> and here is a similiar area on the NSW South Coast that I did prior  
> to the last Mapnik update:
>
> http://www.openstreetmap.org/? 
> lat=-34.702765184192536&lon=150.92087425524562&zoom=12&layers=B0F
>
>
> The sea appears blue correctly at zoom 9, but does not appear at  
> higher zoom levels. Someone must have done 'something' to fix the  
> coast display in the UK.

Only down south. It seems that at Alnmouth on the East Coast it changes.

http://www.openstreetmap.org/? 
lat=55.49963729375684&lon=-1.4114415740600161&zoom=10&layers=B0F
http://www.openstreetmap.org/? 
lat=55.37566766436997&lon=-1.6052472266629831&zoom=14&layers=B0F

>
> Or is it a problem with the coastline data used by Mapnik? I tried  
> to import some of it manually, but it was terrible. I used  
> Lakewalker instead and got a quite good result.
>
There has been some talk of Mapnik using the OSM coastline data so  
that it is more correct. There are some areas around Edinburgh where  
I've had to move the coastline.
http://www.openstreetmap.org/? 
lat=55.982305493683796&lon=-3.1766780462738873&zoom=16&layers=B0F is  
one example of the problem, where osmarender is correct, but mapnik  
is completely out.

Shaun