[OSM-dev] Area rendering on Mapnik

Dave osm at randomjunk.co.uk
Tue Jan 30 12:01:28 GMT 2007

Artem Pavlenko wrote:
> Hi  Nick,
> Could you post this shapefile somewhere, please? I'm not aware of any problems 
> rendering polygons ...   
> Cheers,
> Artem 
> On Tuesday 30 January 2007 10:44, Nick Whitelegg wrote:
>> Hello everyone,
>> A question to those of you (Artem and anyone else) who has rendered mapnik
>> maps - are there any issues with rendering areas (polygons)? I don't seem
>> to be able to render areas consistently when the area crosses the edge of
>> a tile.  I fetch data from the current tile and 25% of the next tile - so
>> points outside of the current tile as well as within should be fetched.
>> Are there any issues to be aware of here? This is using shapefiles for
>> rendering.

Is this using your fmapgen code?
Because if it is, one problem you might have is that the OSM api can
return incomplete ways if some of the segments are outside of the
request bbox... this can lead to all kinds of clipping issues even if
you ask for 25% more: for zoomed in tiles there are still going to be
issues because it'll be connecting the first and last nodes that were
downloaded. The shape file making code appears to just skip segments
which aren't available in the OSM::Components structure.

I'm guessing the postgis db returns the entire polyline whatever, so it
doesn't have these problems.

Of course you may be having a completely different problem.

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