[OSM-dev] OSM-Carto style, ported to vector tiles!

Rory McCann rory at technomancy.org
Mon Jul 25 09:48:47 UTC 2016

On 24/07/16 18:26, Christoph Hormann wrote:
> Ok - so you essentially say that use of !pixel_width! and !pixel_height! 
> is - in the vector tiles system used - limited to the lower zoom 
> levels.

Yes, you can't use *pixel* for z15+. You can hack around it, like I
do[1], with "zoom dependent way_pixel filters". Just divide by 4 each
zoom level.

> That however would also mean you would need to remove all the 
> way_area > 0.01*!pixel_width!::real*!pixel_height!::real
> filters from SQL for z14 - otherwise you get missing geometries at the 
> higher zooms (not a real lot - that limit is about one Mercator square 
> meter at z14 - but when this occurs it would be visible and possibly 
> surprising).

Oops. I will fix that. Do you know of an example of where this filtering
applies in the normal OSM tileserver? It's helpful to have something to
compare to?

> And if i understand you correctly this also means you cannot render any 
> features differently on z14 and any higher zoom level based on 
> processing done in SQL - unless you duplicate them into different 
> separate layers for different zoom levels.

Yes, you can't use SQL to filter different things after z14. You have to
use CartoCSS filters. A z14 tile needs to have all the data a z19 tile
needs to render.

You don't have to use z14. You can use another level, or have all vector
tiles generated live (with no "overzooming"). Not sure why you'd want to
do that.



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