[OSM-talk] Mapnik now not supporting layer=1 on golfcourses

[Artem Pavlenko]

On 14 May 2007, at 19:26, Jon Burgess wrote:

> On Mon, 2007-05-14 at 17:24 +0100, Andy Robinson wrote:
>> We appear to have lost some golf course support in Mapnik in the most
>> recent tiles rendered. Previously (as per osmarender still) golf
>> course areas within parkland where the course has a layer=1 set were
>> rendered one on top of the other for all to see, the current Mapnik
>> tiles are no longer showing these golf courses. Example being:
>>
>>
>>
>> http://www.openstreetmap.org/index.html? 
>> lat=52.5740&lon=-1.8576&zoom=13
>>
>
> It seems that the current code only uses the layer= property to
> determine the drawing order (z_order) on lines and not on polygon  
> areas
> like the golf course & park.
>
> This is the case both for the old setup_z_order.sql script and the
> current osm2pgsql. If it rendered OK before in Mapnik then it was
> probably by luck.
>
> Adding this feature needs changes to both define a z_order for  
> polygons
> and also to use this to sort the data in the osm.xml style.
>
> 	Jon


Ideally, features like that should be represented as polygons with  
holes, which are not supported by current OSM model AFAIK.
As a workaround we could use z_order on polygon layers as suggested  
by Jon. It will produce desired visual results.

<rant to="someone re-inventing the wheel">
Still, I'd like to gently push an idea of a *POLYGON* geometry :).  
POLYGONS are good!!! Don't mess about with geometries!
  </rant>


Cheers,
Artem

>
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Artem Pavlenko
http://mapnik.org



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