Thank you, Dana!
Don't know wether to laugh or to cry now. [?] At least a silly fault of mine.
Now it works.

CC or Janes

2010/9/15 Dane Springmeyer <[email protected]>

>
> On Sep 15, 2010, at 4:55 PM, Janes Huff wrote:
>
> Hi,
> I tried some tests with mapnik using osm data (download brandenburg.osm
> from Geofabrik <http://download.geofabrik.de/osm/europe/germany/>; cut out
> a smaller region with osm2pgsql: osm2pgsql --bbox
> 12.6247,52.2599,13.3848,52.5194 -m -d gis brandenburg.osm). All parts
> (postgis, mapnik, ...) seem to work fine.
>
>
> I created the two files:
>
> *a) werder.py* (origin code I took from here:
> http://trac.mapnik.org/wiki/XMLGettingStarted):
>
> #!/usr/bin/env python
> # -*- coding: utf-8 -*-
> import mapnik
> mapfile = 'werder.xml'
> map_output = 'werder.png'
> m = mapnik.Map(800, 600)
> mapnik.load_map(m, mapfile)
> bbox = mapnik.Envelope(mapnik.Coord(12.6247,52.2599), 
> mapnik.Coord(13.3848,52.5194))
> m.zoom_to_box(bbox)
> mapnik.render_to_file(m, map_output)
>
>
> Your Map is in mercator so you need to pass mercator coordinates to the
> zoom_to_box function.
>
> Here is an example of reprojecting long/lat coords into spherical mercator:
>
>
> http://mapnik-utils.googlecode.com/svn/example_code/google_mercator_projection/world_mercator.py
>
> You can also just render the werder.xml with nik2img.py which will
> automatically zoom to the extents of your data (if set correctly, see
> below).
>
>
> *b) werder.xml*:
>
> <?xml version="1.0" encoding="utf-8"?>
> <!DOCTYPE Map>
> <Map bgcolor="#ffffff" srs="+proj=merc +lon_0=0 +k=1 +x_0=0 +y_0=0 
> +ellps=WGS84 +datum=WGS84 +units=m +no_defs">
>
>
> [...snip...]
>
>
>
>    <Layer name="strassen" status="on" srs="+proj=merc +lon_0=0 +k=1 +x_0=0 
> +y_0=0 +ellps=WGS84 +datum=WGS84 +units=m +no_defs">
>     <StyleName>strassen</StyleName>
>     <Datasource>
>       <Parameter name="type">postgis</Parameter>
>       <Parameter name="password">my-very-secret-pw</Parameter>
>       <Parameter name="host">localhost</Parameter>
>       <Parameter name="port">5432</Parameter>
>       <Parameter name="user">postgres</Parameter>
>       <Parameter name="dbname">gis</Parameter>
>       <Parameter name="table">planet_osm_line</Parameter>
>       <Parameter name="estimate_extent">false</Parameter>
>       <Parameter name="extent">12.6247,52.2599,13.3848,52.5194</Parameter>
>     </Datasource>
>    </Layer>
> </Map>
>
>
>
> Your layer is going to be in spherical mercator () as it was imported with
> the -m flag of osm2pgsql, so that means your extent value must also be in
> spherical mercator coordinates (not long/lat). An easy solution here is to
> let PostGIS calculate the layer's extents automatically (just remove the
> 'extent parameter' to trigger this).
>
>
>
> After execution I get no error message and the PNG-file I waited for. Well,
> but it's blank - sorry - it's background color is #fffff (or whatever color
> I setted). But no map features are shown.
> I searched a lot by now, but couldn't figure out the mistake. Could you
> give me a hint, please?
>
> Thank you,
> CC
>
> P.S.:
> OS: Kubuntu 10.4
> Mapnik: 0.7
> Postgresql: 8.4
> Postgis: 1.5.1
> osm2pgsql: 0.66.20090526
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>
>
>

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