[Geotools-gt2-users] GeoTools and PostGIS with ESPG:3857

[Sergei K. <se...@fa...>]

Hello,
I'm trying to use both PostGIS and GeoTools with the same ESPG:3857
projection, however, it looks like the projections in PostGIS and GeoTools
differ.

This is what I have in PostGIS:
"PROJCS[""WGS 84 / Pseudo-Mercator"",GEOGCS[""WGS
84"",DATUM[""WGS_1984"",SPHEROID[""WGS
84"",6378137,298.257223563,AUTHORITY[""EPSG"",""7030""]],AUTHORITY[""EPSG"",""6326""]],PRIMEM[""Greenwich"",0,AUTHORITY[""EPSG"",""8901""]],UNIT[""degree"",0.0174532925199433,AUTHORITY[""EPSG"",""9122""]],AUTHORITY[""EPSG"",""4326""]],UNIT[""metre"",1,AUTHORITY[""EPSG"",""9001""]],PROJECTION[""Mercator_1SP""],PARAMETER[""central_meridian"",0],PARAMETER[""scale_factor"",1],PARAMETER[""false_easting"",0],PARAMETER[""false_northing"",0],EXTENSION[""PROJ4"",""+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 +nadgrids=@null +wktext
 +no_defs""],AUTHORITY[""EPSG"",""3857""],AXIS[""X"",EAST],AXIS[""Y"",NORTH]]"

Here's GeoTools:
PROJCS["WGS 84 / Pseudo-Mercator",
  GEOGCS["WGS 84",
    DATUM["World Geodetic System 1984",
      SPHEROID["WGS 84", 6378137.0, 298.257223563,
AUTHORITY["EPSG","7030"]],
      AUTHORITY["EPSG","6326"]],
    PRIMEM["Greenwich", 0.0, AUTHORITY["EPSG","8901"]],
    UNIT["degree", 0.017453292519943295],
    AXIS["Geodetic latitude", NORTH],
    AXIS["Geodetic longitude", EAST],
    AUTHORITY["EPSG","4326"]],
  PROJECTION["Popular Visualisation Pseudo Mercator",
AUTHORITY["EPSG","1024"]],
  PARAMETER["semi_minor", 6378137.0],
  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["Easting", EAST],
  AXIS["Northing", NORTH],
  AUTHORITY["EPSG","3857"]]

I've tried using the PostGIS one with GeoTools, but it cannot parse it due
to the EXTENSION element. Of course, I could update PostGIS with the
GeoTools one, but can anyone tell why they are different?

I'm using GeoTools 10.0, and just trying to convert a EPSG:4326 point into
EPSG:3857, and vice versa. The code works:
CoordinateReferenceSystem sourceCRS = CRS.decode("EPSG:4326");
            CoordinateReferenceSystem targetCRS = CRS.decode("EPSG:3857");
            Logger.info(targetCRS.toWKT());
            MathTransform transform = CRS.findMathTransform(sourceCRS,
targetCRS, false);
            GeometryFactory geometryFactory = new GeometryFactory(new
PrecisionModel(), DEFAULT_GEOM);
            Point point = geometryFactory.createPoint(
                    new Coordinate(lon, lat));
            Point targetPoint = (Point) JTS.transform(point, transform);

but I cannot use the targetPoint I create in PostGIS queries. Any solution
of how to make these two work together?