[Proj] Projections with respect to India

Greg Troxel gdt at ir.bbn.com
Sat Jan 9 07:06:19 PST 2010


  I downloaded an OSM map file namely "india.osm.bz2".
  I transported it in PostgreSQL database "gis" with the command :

  ./osm2pgsql -m -d gis india.osm.bz2 


  pgsql2shp -f myfile gis planet_osm_line

  The projection file now generated namely "myfile.prj" contains the following !

  PROJCS["WGS84 / Simple Mercator",GEOGCS["WGS 84",DATUM["WGS_1984",SPHEROID["WGS_1984", 6378137.0, 
  298.257223563]],PRIMEM["Greenwich", 0.0],UNIT["degree", 0.017453292519943295],AXIS["Longitude", 
  EAST],AXIS["Latitude", NORTH]],PROJECTION["Mercator_1SP_Google"],PARAMETER["latitude_of_origin", 
  0.0],PARAMETER["central_meridian", 0.0],PARAMETER["scale_factor", 1.0],PARAMETER["false_easting", 
  0.0],PARAMETER["false_northing", 0.0],UNIT["m", 1.0],AXIS["x", EAST],AXIS["y", NORTH],AUTHORITY["EPSG","900913"]]

This is really an OSM question more than a proj question.

OSM stores data in WGS84 EPGS4326 (in the xml file).  But, osm2pgsql by
default converts to Google Spherical Mercator EPGS:900913.  If you are
trying to use this data in a local coordinate system (an Indian TM or
lambert conformal conic system?), then you are probably better off
importing in EPSG4326.


http://wiki.openstreetmap.org/wiki/Osm2pgsql
http://wiki.openstreetmap.org/wiki/Mapnik#osm2pgsql
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