[OSM-dev] different rendering with mapnik based on area?

[Reinder Verlinde]

In article <20120331191247.GU29037 at aperiodic.net>,
 Phil! Gold <phil_g at pobox.com> wrote:

> * Sven Geggus <lists at fuchsschwanzdomain.de> [2012-03-31 16:06 +0000]:
> > is it possible to have different rendering rules based on the area
> > where rendring takes place using an ordinary mapnik rendering stack
> > (osm2pgsql+mod_tile+tirex)?
> 
> Supposedly yes.  MapQuest uses has three different stylesheets that they
> use for their tiles and the appropriate one is selected based on where the
> rendered data is.
> 
> Unfortunately, I cannot find *any* information online about how this is
> accomplished.  MapQuest's stylesheet repo[0] has the three stylesheets but
> gives no clues about how they're used.  I haven't found anything via
> Internet searches or grepping through the mapnik source code, either.  I'm
> hoping someone else on the list know the magic keywords to look for,
> because I'm kind of stumped.
> 
>   [0]: https://github.com/MapQuest/MapQuest-Mapnik-Style

I guess a way to do it is to have three layers, one for each section of 
the map, and render each with its own stylesheet.

You will have to take care that no part of the map gets rendered 
multiple times, though. That seems doable if the borders are water 
areas. Depending on the style, rendering that twice will not lead to 
artifacts.

Reinder