Today I've updated the Wiki and files in SVN to move over to using the Spherical Mercator projection in Mapnik.
- I've updated the instructions on how to import the new coastline polygons - There are some new world_boundaries shapefiles to work with the spherical projection and removed the redundant coastline information. More details on how to download and import this new data see: http://wiki.openstreetmap.org/index.php/Mapnik For those that are using Mapnik today you'll need to:- - Update to a version of osm2pgsql which supports the "-m" option - Import your OSM data using "-m" - Download the new word_boundaries-spherical.tgz file - Download the coastline polygon shapefile* and import it - Update to the new versions of osm.xml / osm-template.xml - Update to the new generate_tiles.py / generate_image.py I've updated the tools I'm aware of but I've probably missed some. If you've got any other tools which are trying to project to/from the Mapnik projection then you'll generally have to change a projection string like +proj=merc +datum=WGS84 to: +proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m [EMAIL PROTECTED] +no_defs +over The reason this change is that the older projection string gave the wrong answers in some cases. All of the Mapnik tools tended to generate the same wrong answers consistently and overall the error was cancelled out. The larger meta tiles in mod_tile made these small errors cause visible problems on the map. Jon * The coastline polygons available are probably broken right now due to some issues with the Hypercube machine over the past few days. You may be better off waiting a few days and checking the coastline viewer before downloading them. _______________________________________________ dev mailing list [email protected] http://lists.openstreetmap.org/cgi-bin/mailman/listinfo/dev
