Jody Garnett wrote:
>
> The shapefile code will read the prj file for you; the value is
> available as:
>
> CoordianteReferenceSystem sourceCRS =
> shapefiledatastore.getSchema().getDefaultGeometry().getCoordianteReferenceSystem().
>
> I am a bit worried that cannot understand your problem; reading you
> email it sounds like the above value would be a "state plane" format?
> And you may
> be asking how to reproject the data to "EPSG:4326". If you simply want
> find the best match for sourceCRS and ask the data store to use it ...
>
> CoordianteReferenceSystem exactCRS = CRS.lookupIdentifier( sourceCRS,
> true );
> shapefiledatastore.forceCRS( exactCRS ); // this exact CRS from the epsg
> database will be used by the shapefile from here on out
>
> Cheers,
> Jody
>
Thanks for the reply, Jody. As I said, I'm very new, so apologies if I'm
not asking my question very clearly. Basically, what I'm trying to do is
extract the lat/long coordinates of the geometries in a shapefile, but those
geometries are currently represented in a state plane CRS. So my major goal
is to find the MathTransform that goes from input format to EPSG:4326, so
that I can apply this to the geometries in my file and essentially dump out
the resulting lat/long coordinates.
I've tried the code you suggest above. The getCoordina
teReferenceSystem returns a CRS which, when converted to a String, looks
like my .prj file:
PROJCS["NAD_1983_StatePlane_Massachusetts_Mainland_FIPS_2001",
GEOGCS["GCS_North_American_1983",
DATUM["D_North_American_1983",
SPHEROID["GRS_1980", 6378137.0, 298.257222101]],
PRIMEM["Greenwich", 0.0],
UNIT["degree", 0.017453292519943295],
AXIS["Longitude", EAST],
AXIS["Latitude", NORTH]],
PROJECTION["Lambert_Conformal_Conic"],
PARAMETER["central_meridian", -71.5],
PARAMETER["latitude_of_origin", 41.0],
PARAMETER["standard_parallel_1", 41.71666666666667],
PARAMETER["scale_factor", 1.0],
PARAMETER["false_easting", 200000.0],
PARAMETER["false_northing", 750000.0],
PARAMETER["standard_parallel_2", 42.68333333333334],
UNIT["m", 1.0],
AXIS["x", EAST],
AXIS["y", NORTH]]
Notice that there are useful (to a human) names here, but no Bursa Wolf
parameters that would allow this to be easily digested by a machine.
Now when I try your other suggestion: CRS.lookupIdentifier( sourceCRS, true
); I get an exception:
org.opengis.referencing.FactoryException: Geotools extension required for
"getIdentifiedObjectFinder" operation.
at
org.geotools.referencing.factory.AuthorityFactoryAdapter.getGeotoolsFactory(AuthorityFactoryAdapter.java:503)
at
...
It seems I need some tool which will take the name
NAD_1983_StatePlane_Massachusetts_Mainland_FIPS_2001 and make a best guess
as to what EPSG code I need, much as I would do by looking at the EPSG
online database. Can GeoTools do this?
--
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