[MapProxy] Spherical Mercator Projection

Frank Broniewski brfr at metrico.lu
Wed Aug 1 00:02:21 PDT 2012

Hi list,

I have trouble overlaying my own data from a Mapnik source with 
OpenStreetMap tiles. I need/want to use the official EPSG 3857 instead 
of 900913 for my data [1]. From here [2] I read that 3857 is just an 
alias to 900913, so the data should overlay cleanly. But unfortunately I 
have a shift between my data and the OSM tiles.

So how do I need to configure my grids so that they overlay nicely with 
the OSM tiles? Is

   35 grids:
   36     world_mercator:
   37         srs: 'EPSG:3857'
   38         base: GLOBAL_MERCATOR

already enough?

This is keeping me busy (read: driving me mad ;-)) already for a couple 
of days. I tried also

   35 grids:
   36     world_mercator:
   37         srs: 'EPSG:3857'
   38         origin: 'nw'
   39         num_levels: 19
   40         min_res: 156543.0339
   41         bbox: [-180, -85, 180, 85]
   42         bbox_srs: 'EPSG:4326'

and other variations. I also have the problem that the map center is 
jumping around when zooming in. That means when you zoom in, on a city 
for example, that after the zooming process the city is shifted onto 
another position than the zoom position. I am uncertain if this is a 
Mapproxy misconfiguration or if it is on the OpenLayers side, but I used 
the same configuration options on both sides. I still wonder if the 
coverages I use are a cause for this. If only the rendering times would 
be faster testing wouldn't be such a pain ..

So any hints are greatly welcome :-)


[1] one reason for this is, that 900913 isn't in the proj configuration 
[2] http://trac.osgeo.org/openlayers/wiki/SphericalMercator

METRICO s.à r.l.
technologies d'information géographique
rue des Romains 36

tél.: +352 26 74 94 - 28
fax.: +352 26 74 94 99

More information about the MapProxy mailing list