This is quite confusing for Austrian Coordinate Systems. I cant remember exactly, but I think the TOWGS84 clause from the official epsg database is not present or the clause has the values for Slovenia.
None of these possibilities make me happy. I checked the epsg.properties file in trunk. As an example, EPSG 31287 (Austria Lambert) has no TOGWS84 clause. I always have to work with my own wkt definitions, otherwise the results are very inaccurate. Quoting Jody Garnett <jody.garn...@gmail.com>: > Interesting; we should talk this over with the referencing module > maintainer and probably issue a bug report? > Jean you were understanding the steps as I described them; > apparently the information is not available :-( > > The "equalsIgnoresMetadata" method is used internally by the CRS > class as it tries to find a "match" for you. > > > Jody > > On 18/05/2010, at 2:22 AM, christian.muel...@nvoe.at wrote: > >> I had the same problems with bursa wolf params for coordinate systems >> in Austria and this ended in parsing my own wkt defenitions. >> Afterwards, everything works fine. >> >> Quoting Jean Marie <jm...@hotmail.fr>: >> >>> >>> Hi Jody >>> >>> I tried to debug from line : >>> >>> String code = CRS.lookupIdentifier( example, true ); // should be >>> "EPSG:4230" >>> >>> and from >>> >>> CoordinateReferenceSystem crs = CRS.decode( code ); >>> >>> but I didn't come accross the method "equalsIgnoresMetadata" >>> although this method is visible several times in CRS.java ; >>> >>> if you are talking about a method equalsIgnoresMetadata inside of >>> CRS.java, I wonder from which method you get there ; >>> I must miss something... >>> >>> by the way I noticed that CRS.java has a main class that can display >>> the Bursa-Wolf parameters using parameter -bursawolfs >>> in a command line >>> >>> unfortunately for "EPSG:27572" no Bursa-Wolf parameter are displayed >>> (even if it requires gt-epsg-hsql-2.6.3.jar) ! >>> here is the result : >>> >>> ??????????????????????????????????????????????????? >>> ? Destination ? dx ? dy ? dz ? ex ? ey ? ez ? ppm ? >>> ??????????????????????????????????????????????????? >>> ??????????????????????????????????????????????????? >>> >>> in desperation, I took the Bursa-Wolf parameters from the >>> spatialreference.org site which gives a correct result, >>> namely TOWGS84[-168,-60,320,0,0,0,0] (and using only >>> gt-referencing-2.6.3.jar) >>> >>> If I can really get the parameters from the debug process it would >>> be reassuring >>> >>> thanks anyway >>> >>> Jean-Marie >>> >>> Subject: Re: [Geotools-devel] how to get Bursa-Wolf parameters in >>> WKT strings >>> From: jody.garn...@gmail.com >>> Date: Mon, 17 May 2010 20:29:01 +1000 >>> CC: geotools-gt2-users@lists.sourceforge.net >>> To: jm...@hotmail.fr >>> >>> >>> >>> Hi Jean - we should keep this on the email list. >>> Can you try the code example and step through it with a debugger? >>> This should help explain why it will hep you.1. You parse the WKT >>> into a CoordinateReferenceSystem2. You look for a matching >>> CoordinateReferenceSystem coming out of the official EPSG database >>> Inside that code it goes through and checks for a >>> CoordinateReferenceSystem with the same values as yours; ignoring >>> the metadata (such as name and description). The method is called >>> "equalsIgnoresMetadata" if you are interested.3. It returns you a >>> match ... and that match includes Bursa Wolf Parameters >>> Jody >>> On 17/05/2010, at 7:37 PM, Jean Marie wrote:Hi jody >>> >>> I had a look at the example given at : >>> >>> http://docs.codehaus.org/display/GEOTDOC/01+CRS+Helper+Class#01CRSHelperClass-SearchingforaCoordinateReferenceSystem >>> >>> I think you refer to the following code : >>> ----- >>> String code = CRS.lookupIdentifier( example, true ); // should be >>> "EPSG:4230"CoordinateReferenceSystem crs = CRS.decode( code ); >>> ------ >>> >>> well I don't know how this can help me ; >>> >>> you talked also about an "Equals" method that could assist me ; >>> well I don't see how >>> >>> if you could give me some further details it would be helpfull >>> as I don't know how to sort out this problem of String WKT >>> which sometimes contains all parameters required and sometimes doesn't >>> >>> thanks a lot >>> >>> Jean-Marie >>> >>> >>> Subject: Re: [Geotools-devel] how to get Bursa-Wolf parameters in >>> WKT strings >>> From: jody.garn...@gmail.com >>> Date: Thu, 13 May 2010 08:35:11 +1000 >>> CC: geotools-de...@lists.sourceforge.net >>> To: jm...@hotmail.fr >>> >>> Hi Jean >>> Here is what I kind of do; I use the CoordinateReferenceSystem >>> created my WKT to look up the "Real" CoordinateReferenceSystem >>> produced by the EPSG database (which is much more complete). >>> There is an "Equals" method that ignores metadata to assist you with >>> this; and because I find CoordinateReferenceSystem stuff difficult >>> to manage by hand there should be a helper method ... >>> Yes there is - indeed it is one of the use-cases covered by the user >>> >>> guide:-http://docs.codehaus.org/display/GEOTDOC/01+CRS+Helper+Class#01CRSHelperClass-SearchingforaCoordinateReferenceSystem >>> Cheers, Jody >>> On 13/05/2010, at 3:15 AM, Jean Marie wrote:Hello >>> >>> my purpose is to get a list of projection systems described in a WKT >>> format (so using gt-epsg-hsql-2.6.3) ; >>> and then to use these WKT representations to achieve tranformations >>> using only >>> the library gt-referencing-2.6.3.jar >>> >>> to get these WKT strings I use the following code : >>> >>> CoordinateReferenceSystem crsSrc = >>> ReferencingFactoryFinder.getCRSAuthorityFactory("EPSG", >>> null).createCoordinateReferenceSystem(EPSG); >>> and then crsSrc.toWKT() gives the WKT specification for EPSG >>> >>> I took 3 WKT representations for respectively EPSG = "EPSG:4326", >>> EPSG = "EPSG:2056" and EPSG = "EPSG:27572" >>> then I created for each one a CoordinateOperationFactory object to >>> carry out 2 transformations : >>> one from 4326 to 2056 (Switzerland) et the other from 4326 to 27572 >>> (France) using the WKT strings >>> >>> I noticed that the WGS84 to Swiss transformation is correct, >>> while the WGS84 to French transformation generates an error saying >>> that Bursa-Wolf parameters are required ; >>> >>> I would like to know how to sort out this problem as I need >>> accurate results >>> and I cannot afford to use the following code involving some >>> transformation errors: >>> >>> CRS.findMathTransform(crsSrc, crsDest, true) >>> >>> is it possible to get Bursa-Wolf parameters in each WKT representation ? >>> >>> thanks a lot >>> >>> Jean-Marie >>> >>> Vous voulez protéger votre vie privée ? 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