Hi, I just read this message and thought that this could be a problem in the EPSG database again. Are you using version 6.11.2 (Bursa Wolf params seem to be missing!)? In that case try 6.11 which contains the Bursa Wolf Parameters.
An additional problem using the Gauss-Kruger system could be that there are different sets of Bursa Wolf parameters. On the net and in the EPSG database you find the following versions EPSG: "612.4, 77.0, 440.2, -0.054, 0.057, -2.797, 0.5259752559300956"; Alternative 3: "587.0, 16.0, 393.0, 0., 0., 0., 0."; Alternative 2: "582.0, 105.0, 414.0, -1.04, -0.35, 3.08, 9.0"; Alternative 1: "586.0, 87.0, 409.0, -0.52, -0.15, 2.82, 9.0"; I had this problem some weeks ago. Does somebody have a hint which params are the most commonly used? Cheers Helge > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On > Behalf Of Wegert > Sent: Wednesday, December 13, 2006 1:33 PM > To: [email protected] > Subject: Re: [Geotools-gt2-users] Google Earth - Projection > > > Hi Rueben, > thanks for your reply. > > I have already created CRS's with an authority factory. > The created CRS returns the following informations with > "System.out.println(sourcecrs)": > > > > > PROJCS["DHDN / Gauss-Kruger zone 2", > > GEOGCS["DHDN", > > DATUM["Deutsches_Hauptdreiecksnetz", > > SPHEROID["Bessel 1841", 6377397.155, 299.1528128, > > AUTHORITY["EPSG","7004"]], > > AUTHORITY["EPSG","6314"]], > > PRIMEM["Greenwich", 0.0, AUTHORITY["EPSG","8901"]], > > UNIT["degree", 0.017453292519943295], > > AXIS["Lon", EAST], > > AXIS["Lat", NORTH], > > AUTHORITY["EPSG","4314"]], > > PROJECTION["Transverse_Mercator"], > > PARAMETER["central_meridian", 6.0], > > PARAMETER["latitude_of_origin", 0.0], > > PARAMETER["scale_factor", 1.0], > > PARAMETER["false_easting", 2500000.0], > > PARAMETER["false_northing", 0.0], > > UNIT["m", 1.0], > > AXIS["x", EAST], > > AXIS["y", NORTH], > > AUTHORITY["EPSG","31466"]] > > > > The problem is, that the BursaWolfParameter (TOWGS84[]) is missing! > > The WKT should look like: > > > > > PROJCS[\"DHDN / Gauss-Kruger zone 2\", GEOGCS[\"DHDN\", > > DATUM[\"Deutsches_Hauptdreiecksnetz\", > > SPHEROID[\"Bessel 1841\", 6377397.155, 299.1528128, > > AUTHORITY[\"EPSG\",\"7004\"]], TOWGS84[598.1, 73.7, 418.2, > > 0.2019999999999998, 0.04499999999999995, -2.4549999999999974, > > 1.3819742018555456], AUTHORITY[\"EPSG\",\"6314\"]], > > PRIMEM[\"Greenwich\", 0.0, AUTHORITY[\"EPSG\",\"8901\"]], > > UNIT[\"degree\",0.01745329251994328, AUTHORITY[\"EPSG\",\"9122\"]], > > AUTHORITY[\"EPSG\",\"4314\"]], PROJECTION[\"Transverse_Mercator\"], > > PARAMETER[\"latitude_of_origin\",0], > > PARAMETER[\"central_meridian\",6], > > PARAMETER[\"scale_factor\",1], PARAMETER[\"false_easting\",2500000], > > PARAMETER[\"false_northing\",0], > > UNIT[\"metre\",1,AUTHORITY[\"EPSG\",\"9001\"]], > > AUTHORITY[\"EPSG\",\"31466\"]] > > > > Here are the TOWGS84[] parameters included! > > But I have to do this manually....or does a library exist, > which contains the WKT "with" TOWGS84[] parameters? > Maybe a look-up table would be usefull.... > > I'm doing the following steps to transform a point > (optionally I could create the CRS by WKT): > > > > > private Point2D.Double getPointAsLatLong(Point2D.Double point){ > > > > > > CoordinateReferenceSystem sourcecrs = > > FactoryFinder.getCRSAuthorityFactory("EPSG", > > null).createCoordinateReferenceSystem("EPSG:31467"); > > CoordinateReferenceSystem targetcrs = > > FactoryFinder.getCRSAuthorityFactory("EPSG", > > null).createCoordinateReferenceSystem("EPSG:4326"); > > > > CoordinateOperationFactory coFactory = FactoryFinder > > .getCoordinateOperationFactory(null); > > CoordinateOperation op = > > coFactory.createOperation(sourcecrs, > > targetcrs); > > > > GeneralDirectPosition gdp = new > GeneralDirectPosition(0, 0); > > gdp.setOrdinate(0, point.getX()); > > gdp.setOrdinate(1, point.getY()); > > op.getMathTransform().transform(gdp, gdp); > > > > outPoint.x = gdp.getOrdinate(0); > > outPoint.y = gdp.getOrdinate(1); > > > > > > return outPoint; > > > > So, what's wrong? > > > Best regards > Sebastian > > > > > > > > > Rueben Schulz wrote: > > > > To Sebastian, > > > > Hi. You can get the towgs84 parameters you need from the > EPSG database. > > The easiest way to do this is to use an authority factory > to create a > > CRS from an EPSG code (31466 in your case). The returned CRS should > > have the towgs84 (BursaWolf) parameters included, which > will be used > > to create the correct transformation. > > > > An example of how to create a CRS from authority codes can > be found in: > > > > > http://svn.geotools.org/geotools/trunk/gt/demo/referencing/src/main/ja > > va/org/geotools/demo/referencing/CTSTutorial.java > > > > Note, Zone 3 of your projection is given in the command > line example > > at the end of: > > > > http://geotools.codehaus.org/Coordinate+Transformation+Services+for > > +Geotools+2.1 > > > > so I expect that the EPSG database has the towgs84 > parameters that you > > need. > > > > Rueben > > > > > > > > > > > > On Tue, 2006-12-12 at 04:18 -0800, Wegert wrote: > >> Hallo all, > >> > >> At the moment, I'm trying to project points, lines and polygons on > >> "Google Earth". To achieve this aim, I'm using GEOTOOLS. > >> > >> Now to the problem: > >> > >> As Martin Desruisseaux wrote in his answer ( > >> > http://sourceforge.net/mailarchive/message.php?msg_id=15645183 ) you > >> can't set Hints.LENIENT_DATUM_SHIFT to Boolean.TRUE, if > you want an > >> accurate transformation. > >> For example, the projection from GK2 (Gauß-Krüger 2) to > WGS84 (as far > >> as I know this is the basis CRS of Google Earth) results in a > >> deviation of about 200 metres, always. (btw: You can take > a look at > >> the screenshot in the > >> attachment!) > >> > >> > >> > >> > >> Here are some informations about the transformation: > >> > >> sourcecrs: > >> > >> PROJCS["DHDN / Gauss-Kruger zone 2", > >> GEOGCS["DHDN", > >> DATUM["Deutsches_Hauptdreiecksnetz", > >> SPHEROID["Bessel 1841", 6377397.155, 299.1528128, > >> AUTHORITY["EPSG","7004"]], > >> AUTHORITY["EPSG","6314"]], > >> PRIMEM["Greenwich", 0.0, AUTHORITY["EPSG","8901"]], > >> UNIT["degree", 0.017453292519943295], > >> AXIS["Lon", EAST], > >> AXIS["Lat", NORTH], > >> AUTHORITY["EPSG","4314"]], > >> PROJECTION["Transverse_Mercator"], > >> PARAMETER["central_meridian", 6.0], > >> PARAMETER["latitude_of_origin", 0.0], > >> PARAMETER["scale_factor", 1.0], > >> PARAMETER["false_easting", 2500000.0], > >> PARAMETER["false_northing", 0.0], > >> UNIT["m", 1.0], > >> AXIS["x", EAST], > >> AXIS["y", NORTH], > >> AUTHORITY["EPSG","31466"]] > >> > >> > >> targetcrs: > >> > >> GEOGCS["WGS 84", > >> DATUM["WGS_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["Lon", EAST], > >> AXIS["Lat", NORTH], > >> AUTHORITY["EPSG","4326"]] > >> > >> > >> > >> Result of System.out.println(transform): > >> > >> CONCAT_MT[INVERSE_MT[PARAM_MT["Transverse_Mercator", > >> PARAMETER["semi_major", 6377397.155], > >> PARAMETER["semi_minor", 6356078.962818189], > >> PARAMETER["central_meridian", 6.0], > >> PARAMETER["latitude_of_origin", 0.0], > >> PARAMETER["scale_factor", 1.0], > >> PARAMETER["false_easting", 2500000.0], > >> PARAMETER["false_northing", 0.0]]], > >> PARAM_MT["Molodenski", > >> PARAMETER["dim", 2], > >> PARAMETER["dx", 0.0], > >> PARAMETER["dy", 0.0], > >> PARAMETER["dz", 0.0], > >> PARAMETER["src_semi_major", 6377397.155], > >> PARAMETER["src_semi_minor", 6356078.962818189], > >> PARAMETER["tgt_semi_major", 6378137.0], > >> PARAMETER["tgt_semi_minor", 6356752.314245179]]] > >> > >> > >> As you can see, the translation parameters "dx", "dy", > "dz" are equal > >> to "0.0". > >> > >> > >> The coordinates of the given point (highlighted in the > screenshot) in > >> GK2 > >> are: > >> > >> X: 2662992.3037465196 > >> Y: 5543456.129133454 > >> > >> > >> The results of GEOTOOLS for WGS84 are: > >> > >> X: 8.274064947588457 > >> Y: 50.00686449018631 > >> > >> > >> Though, the result has to be: > >> > >> X: 8.27317386543231; > >> Y: 50.0050926651181; > >> > >> I calculated this with "Postgres" and checked it visually > and these > >> are nearly the correct coordinates ( < 2 metres)! > >> > >> > >> I need the general way for every kind of transformation from one > >> chosen coordinate system into WGS84...if it's possible. > >> > >> What should I set for the "BursaWolfParameter", which is > required if > >> I won't set Hints.LENIENT_DATUM_SHIFT to Boolean.TRUE and > how does it > >> work? > >> > >> > >> I would be grateful for every response.... > >> Best regards > >> Sebastian > >> > >> http://www.nabble.com/file/4554/projection.JPG > > > > > > > ---------------------------------------------------------------------- > > --- Take Surveys. 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