## geotools-gt2-users

 [Geotools-gt2-users] Transformation question From: Martin Schmitz - 2007-07-16 10:44:45 ```Hello again, I use GT 2.3.1 and have problems to transformate the following CRS to WGS8= 4 (and vice versa). I got the CRS definition from my customer, who created= it especially for his investigation area in Morocco: PROJCS["Lambert=5FIMPETUS=5FMarokko", GEOGCS["GCS=5FMerchich=5FDegree", DATUM["D=5FMerchich",SPHEROID["Clarke=5F1880=5FIGN",6378249.2,293.46602]], PRIMEM["Greenwich",0.0], UNIT["Degree",0.0174532925199433] ], PROJECTION["Lambert=5FConformal=5FConic"], PARAMETER["False=5FEasting",500000.0], PARAMETER["False=5FNorthing",300000.0], PARAMETER["Central=5FMeridian",-5.4], PARAMETER["Standard=5FParallel=5F1",31.7239256472], PARAMETER["Standard=5FParallel=5F2",34.8664576558], PARAMETER["Scale=5FFactor",1.0], PARAMETER["Latitude=5FOf=5FOrigin",33.3], UNIT["Meter",1.0] ] The instantiation of the CoordinateReferenceSystem 'moroccoCRS' by CRS.dec= ode(crsString, true) succeeds. But creating the transformation by CRS.findMathTransform(DefaultGeographic= CRS.WGS84, moroccoCRS) leads to an exception with "Bursa wolf parameters r= equired" message. Using CRS.findMathTransform(DefaultGeographicCRS.WGS84, = moroccoCRS, true) causes no exception, but the transformation seems not to= work well, certainly because the lenient-parameter (TRUE) instructs findM= athTransform(..) to ignore any datum shift. My main problem is, that I don't know, what "Bursa wolf parameters" are fo= r, and how to set them... Thanks for help. Martin Schmitz =5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F= Erweitern Sie FreeMail zu einem noch leistungsst=E4rkeren E-Mail-Postfach! =09 Mehr Infos unter http://produkte.web.de/club/=3Fmc=3D021131 ```
 Re: [Geotools-gt2-users] Transformation question From: Edward Nash - 2007-07-16 10:56:21 ```Martin Schmitz wrote: > ... > My main problem is, that I don't know, what "Bursa wolf parameters"= are for, and how to set them... > ... Have a look at=20 http://www.posc.org/Epicentre.2_2/DataModel/ExamplesofUsage/eu_cs35.h= tml=20 (search for "Bursa Wolf" in the text) for an explanation of what the= =20 parameters are and how they are used (basically to define the=20 relationship and a transformation between the spheroid being used and= =20 the WGS84 spheroid) and=20 http://geoapi.sourceforge.net/2.0/javadoc/org/opengis/referencing/doc= -files/WKT.html#TOWGS84=20 for how to set the parameters in WKT. Probably you need to ask your customer what values should be used, as= =20 they should have these parameters defined for their area (a set of= =20 global parameters will give a less accurate transformation, but may= =20 still be acceptable if you or your customer can find some). Regards, Edward Nash --=20 preagro TP7 - Geodateninfrastruktur http://www.preagro.de Universit=E4t Rostock Agrar- und Umweltwissenschaftliche Fakult=E4t Professur f=FCr Geod=E4sie und Geoinformatik Justus-von-Liebig-Weg 6 18059 Rostock Tel: +49 381 498 3212 Fax: +49 381 498 3202 Web: http://www.auf.uni-rostock.de/gg ```
 Re: [Geotools-gt2-users] Transformation question From: Jody Garnett - 2007-07-16 18:32:55 ```Thanks for the helpful answer Mr Nash; I have copied the references you gave to the wiki: - http://docs.codehaus.org/display/GEOTDOC/03+CoordinateReferenceSystem Jody Edward Nash wrote: > Martin Schmitz wrote: > > ... > >> My main problem is, that I don't know, what "Bursa wolf parameters" are for, and how to set them... >> > > ... > > Have a look at > http://www.posc.org/Epicentre.2_2/DataModel/ExamplesofUsage/eu_cs35.html > (search for "Bursa Wolf" in the text) for an explanation of what the > parameters are and how they are used (basically to define the > relationship and a transformation between the spheroid being used and > the WGS84 spheroid) and > http://geoapi.sourceforge.net/2.0/javadoc/org/opengis/referencing/doc-files/WKT.html#TOWGS84 > for how to set the parameters in WKT. > > Probably you need to ask your customer what values should be used, as > they should have these parameters defined for their area (a set of > global parameters will give a less accurate transformation, but may > still be acceptable if you or your customer can find some). > > Regards, > > Edward Nash > > ```
 Re: [Geotools-gt2-users] Transformation question From: Martin Desruisseaux - 2007-07-20 18:03:12 ```Martin Schmitz a écrit : > PROJCS["Lambert_IMPETUS_Marokko", > GEOGCS["GCS_Merchich_Degree", > DATUM["D_Merchich",SPHEROID["Clarke_1880_IGN",6378249.2,293.46602]], > (...snip...) > > My main problem is, that I don't know, what "Bursa wolf parameters" are for, and how to set them... This is the TOWGS84[...] element that appears with DATUM. It contains up to 7 numeric values. I don't know from memory what are the values for "Clarke 1880". You can probably find them by looking in the EPSG database or maybe by searching on internet... Martin ```