Better take a moment to read the user guide.
You need to have access to the definitions of the epsg codes; by including
*one* of the epsg plugins listed on this page:
- http://docs.codehaus.org/display/GEOTDOC/07+Referencing
I recommend gt-epsg-hsql
Jody
On 01/02/2011, at 6:49 AM, Lopes, Jose (AAFC-AAC) wrote:
> Hi Jody,
>
> I found some interesting examples from GeoTools 2.1, 2.2, 2.6 and 2.7
> and they are quite different.
> I am using Geotools 2.7 and the code I came up with is this:
>
> //Vividsolutions classes
> GeometryFactory geoFact = new GeometryFactory();
> Coordinate coordinate = new Coordinate(577147.49750272d,
> 1252040.3464034d);
> Point point = geoFact.createPoint(coordinate);
>
> //GeoTools classes
> CoordinateReferenceSystem epsg26913CRS = CRS.decode("EPSG:26913");
> CoordinateReferenceSystem epsg4326CRS = CRS.decode("EPSG:4326", true);
>
> boolean lenient = true; // allow for some error due to different datums
> MathTransform transform = CRS.findMathTransform(epsg26913CRS,
> epsg4326CRS, lenient);
> Point newPoint = (Point) JTS.transform(point, transform);
>
> The problem is that I am getting this exception on the CRS.decode
> method:
>
> org.opengis.referencing.NoSuchAuthorityCodeException: Authority "EPSG"
> is unknown or doesn't match the supplied hints. Maybe it is defined in
> an unreachable JAR file?
>
> It compiles and run ok but it looks like I might be missing some
> dependencies.
> I have the following libraries in my app:
>
> gt-api-2.7-SNAPSHOT.jar
> gt-main-2.7-SNAPSHOT.jar
> gt-metadata-2.7-SNAPSHOT.jar
> gt-referencing-2.7-SNAPSHOT.jar
> gt-shapefile-2.7-SNAPSHOT.jar
> gt-swing-2.7-SNAPSHOT.jar
>
> I need to use as few libraries as possible... So cannot download all
> the Maven Geotools repository.
> Do you know what gt jar am I missing?
>
> Thanks
>
> -----Original Message-----
> From: Jody Garnett [mailto:[email protected]]
> Sent: January 29, 2011 7:01 PM
> To: Lopes, Jose (AAFC-AAC)
> Cc: [email protected]
> Subject: Re: [Geotools-gt2-users] Transforming CRS projections in
> GeoJSON
>
>
> There is code to parse GeoJSON; not sure how much it is used however.
>
>
> To get up to speed with coordinate reference systems and so on check out
> the tutorials:
> - http://docs.geotools.org/latest/tutorials/
>
>
> (Most of the time there are two helper classes that do the work for you
> "JTS" and "CRS").
>
>
> Jody
>
>
>
>
> On 29/01/2011, at 7:22 AM, Lopes, Jose (AAFC-AAC) wrote:
>
>
> Hi,
>
> I have a set of supported CRS projections (EPSG) and I want to
> transform them to longitude-latitude (EPSG:4326), the information is
> presented in a GeoJson file.
>
> In JS with OpenLayers I could do this in one line
> (OpenLayers.Projection.transform(point, projFrom, projTo).
>
> Is there a simple way to do this in Java with GeoTools? (I have not
> worked with GeoTools referencing libraries yet...)
>
> Thanks for any help-tips...
>
> Jose
>
>
>
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