Ogr2ogr projection problem- features are shifted 12 miles to the north?

Question

I have discovered a problem related to the output of an ogr2ogr command line call. My resulting polygon features are 12 miles (.18 degrees) due north of where they should be, but the longitude is correct. The polygon dimensions are also preserved.

The desired output is a shapefile that has been projected using EPSG 4326. The input comes from a postgres database with postgis where the polygon were digitized in EPSG 900913 (the Google Web Mercator prj).

Below is the command line call that I am using:

ogr2ogr -where " gid = 3 " -f "ESRI Shapefile" E:\Web_Data_Storage\dfr_map_shapes\DFRmap_Tract_3_4326.shp -t_srs EPSG:4326 PG:"user=dfr_webmap dbname=denr host=ipaddress password=xxx port=5433" Tracts2

If I convert the coordinates of a corner of a polygon using gdaltransform I get the correct coordinates.

gdaltransform -s_srs EPSG:900913 -t_srs EPSG:4326 -8853154 4197094.5

Why is this happening and how do I fix it?

Thanks.

Answer 1

I had a similar problem which I solved by replacing the 900913 SRID definition in the spatial_ref_sys table of the originating database with this one (to which I was directed by the TileStache.Vector documentation).