I've downloaded a map from http://factfinder2.census.gov/faces/tableservices/jsf/pages/productview.xhtml?pid=DEC_10_SF1_P1 (limited to San Francisco census tracts), and I'd like to convert it to KML format. However, after unzipping the shapefile .zip file and running
$ ogr2ogr -f KML pop_by_census_tract.kml 140_00.shp
I get the following error message:
ERROR 6: No translation for Mercator_Auxiliary_Sphere to PROJ.4 format is known. Warning 1: Failed to create coordinate transformation between the input coordinate system and WGS84. This may be because they are not transformable, or because projection services (PROJ.4 DLL/.so) could not be loaded. KML geometries may not render correctly. This message will not be issued any more. Source: PROJCS["WGS_1984_Web_Mercator_Auxiliary_Sphere", GEOGCS["GCS_WGS_1984", DATUM["WGS_1984", SPHEROID["WGS_1984",6378137.0,298.257223563]], PRIMEM["Greenwich",0.0], UNIT["Degree",0.0174532925199433]], PROJECTION["Mercator_Auxiliary_Sphere"], PARAMETER["False_Easting",0.0], PARAMETER["False_Northing",0.0], PARAMETER["Central_Meridian",0.0], PARAMETER["Standard_Parallel_1",0.0], PARAMETER["Auxiliary_Sphere_Type",0.0], UNIT["Meter",1.0]] ERROR 1: Latitude 4553026.920500 is invalid. Valid range is [-90,90]. This warning will not be issued any more Warning 1: Longitude -13627851.842700 has been modified to fit into range [-180,180]. This warning will not be issued any more
When I open the resulting KML file in Google Earth, I get randomly scattered lines across the entire planet. The example at code.google.com/apis/kml/articles/vector.html works fine, so the installation of GDAL (1.8.0 from macports) isn't totally broken.
http://trac.osgeo.org/gdal/ticket/3962 seems related, but I'm not sure if it's saying that Mercator_Auxiliary_Sphere is just not supported by GDAL, or if it's implying I should pass another command line option to make it work.
Edit: I wound up accomplishing my goal by downloading http://www2.census.gov/geo/tiger/GENZ2010/gz_2010_06_140_00_500k.zip, which contains shapefiles that ogr2ogr and shp2pgsql can understand, and joining it with the pure table data from factfinder2. I'm still curious about the format factfinder2 is using, but it's no longer blocking progress for me.