Hi list,
i figured out why the accuracy was so bad using the towgs84-Option: the scaling was not in parts per million indicated wrong scaling-specification: --------------------------------------------- => 1.00001651559 ogr2ogr -s_srs "+proj=tmerc +lat_0=0 +lon_0=6 +x_0=2500000 +y_0=0 +ellps=bessel +units=m +towgs84=590.1181,99.6226,340.1890,1.185095,-1.334952,-2.904521,1.00001651559" -t_srs "+proj=utm +ellps=GRS80 +datum=WGS84 +zone=32" -f GML points_7P_gdal.gml points.gml right scaling-specification: --------------------------------------------- => 16.51559 (ppm) ogr2ogr -s_srs "+proj=tmerc +lat_0=0 +lon_0=6 +x_0=2500000 +y_0=0 +ellps=bessel +units=m +towgs84=590.1181,99.6226,340.1890,1.185095,-1.334952,-2.904521,16.51559" -t_srs "+proj=utm +ellps=GRS80 +datum=WGS84 +zone=32" -f GML points_7P_gdal.gml points.gml ----------------------------------------------------------------------------------------------------------- Results | difference East[m] | North[m] | E | N | distance ----------------------------------------------------------------------------------------------------------- 340408,046 5617072,499 -0,013 -0,012 0,018 342695,227 5614819,736 0,003 0,013 0,013 343584,887 5608927,612 0,014 0,026 0,030 ========= Accuracy: ========= ~ 0.3 m Best Regards, Greg >---------- Weitergeleitete Nachricht ---------- > >Betreff: SRS-Transformation(DHDN/GK=>ETRS89/UTM) with towgs84 - Accuracy >Datum: Mittwoch 04 März 2009 >Von: Gregor Fikoczek <gregor.fikoc...@wheregroup.com> >An: gdal-dev@lists.osgeo.org > > >Hi list, > >i am trying to transform some point (in a gml-file) from DHDN/GK3 - srs to >ETRS89/UTM - srs in some diferent ways: > > >some points(gml-File) in start-srs >----------------------------------------------------------------------------------------------------------- >Pointnr. | X[m] | Y[m] >----------------------------------------------------------------------------------------------------------- >5216100002 | 2552401,862 | 5616707,524 >5414100047 | 2554778,697 | 5614549,001 >5508100055 | 2555906,314 | 5608696,986 > >some points(gml-File) in target-srs >----------------------------------------------------------------------------------------------------------- >Punktnr. | East[m] | North[m] >----------------------------------------------------------------------------------------------------------- >5216100002 32340408,033 5617072,487 >5414100047 32342695,230 5614819,749 >5508100055 32343584,901 5608927,638 > > >1.) using the srs defined in the proj-epsg-File: > >ogr2ogr -s_srs EPSG:31466 -t_srs EPSG:25832 -f GML points_etrs_gdal.gml >points.gml > >----------------------------------------------------------------------------------------------------------- >Results | difference >East[m] | North[m] | E | N > | distance >----------------------------------------------------------------------------------------------------------- >340411,269 | 5617068,431 | -3,236 | 4,056 | 5,188 >342698,445 | 5614815,708 | -3,215 | 4,041 | 5,164 >343588,142 | 5608923,646 | -3,241 | 3,992 | 5,142 > > >2.) using a nadgrid (BETA 2007) > >ogr2ogr -s_srs "+proj=tmerc +lat_0=0 +lon_0=6 +k=1.000000 +x_0=2500000 +y_0=0 >+ellps=bessel +units=m +nadgrids=./BETA2007.gsb +wktext" -t_srs "+proj=utm >+ellps=GRS80 +datum=WGS84 +zone=32" -f GML points_BETA2007_gdal.gml >points.gml > >----------------------------------------------------------------------------------------------------------- >Results | difference >East[m] | North[m] | E | N > | distance >----------------------------------------------------------------------------------------------------------- >340408,064 | 5617072,481 | -0,031 | 0,006 | 0,031 >342695,246 | 5614819,723 | -0,016 | 0,026 | 0,031 >343584,918 | 5608927,610 | -0,017 | 0,028 | 0,033 > >3.) using towgs-option (Transform-Parameter) > >ogr2ogr -s_srs "+proj=tmerc +lat_0=0 +lon_0=6 +x_0=2500000 +y_0=0 >+ellps=bessel +units=m >+towgs84=590.1181,99.6226,340.1890,1.185095,-1.334952,-2.904521,1.00001651559" >-t_srs "+proj=utm >+ellps=GRS80 +datum=WGS84 +zone=32" -f GML points_7P_gdal.gml points.gml > >----------------------------------------------------------------------------------------------------------- >Results | difference >East[m] | North[m] | E | N > | distance >----------------------------------------------------------------------------------------------------------- >340408,056 | 5617072,821 | -0,023 | -0,334 | 0,334 >342695,237 | 5614820,058 | -0,007 | -0,309 | 0,309 >343584,897 | 5608927,933 | 0,004 | -0,295 | 0,295 > > >Parameter: >dX +590.1181m >dY +99.6226 m >dZ +340.1890 m >rX +1.185095" >rY -1.334952" >rZ -2.904521" >dm = 1.00001651559 > > >========= >Accuracy: >========= >1.) ~ 5m >2.) ~ 0.033 m >3.) ~ 0.3 m <=== Why so bad ??? > >The accurancy by using the towgs-option is worse then expected, i was >expecting ~ 0.02 m. Aspacielly the difference in North >(-0,334, -0,309, -0,295) is remarkable. > >So maybe an algebraic sign is incorrect or what ever, anybody a suggestion? > >Best regards, >Greg > --------------------------------------- WhereGroup GmbH & Co. KG Siemensstraße 8 53121 Bonn Germany Gregor Fikoczek Email: gregor.fikoc...@wheregroup.com Fon: +49 (0)228 / 90 90 38 - 25 Fax: +49 (0)228 / 90 90 38 - 11 i...@wheregroup.com www.wheregroup.com Amtsgericht Bonn, HRA 6788 ------------------------------- Komplementärin: WhereGroup Verwaltungs GmbH vertreten durch: Olaf Knopp, Peter Stamm --------------------------------------- ------------------------------------------------------- -- Mit freundlichen Grüßen / Kind regards Gregor Fikoczek --------------------------------------- WhereGroup GmbH & Co. KG Siemensstraße 8 53121 Bonn Germany Gregor Fikoczek Email: gregor.fikoc...@wheregroup.com Fon: +49 (0)228 / 90 90 38 - 25 Fax: +49 (0)228 / 90 90 38 - 11 i...@wheregroup.com www.wheregroup.com Amtsgericht Bonn, HRA 6788 ------------------------------- Komplementärin: WhereGroup Verwaltungs GmbH vertreten durch: Olaf Knopp, Peter Stamm --------------------------------------- _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev
