On Thursday 16 July 2009 20:59:55 Even Rouault wrote: > Le Thursday 16 July 2009 10:14:27 Jørn Vegard Røsnes, vous avez écrit : > > Hi again, > > > > On Wednesday 15 July 2009 13:12:38 Jørn Vegard Røsnes wrote: > > > Hi all, > > > > > > can you see the problem (this works with proj4)? > > > It works if I remove "+a=6378273" from proj4-string, but I assume the > > > output will be wrong. > > > > > > ./ogr2ogr -s_srs EPSG:4326 -t_srs "+proj=stere +lat_0=90 +lon_0=315 > > > +lat_ts=70 +units=m +a=6378273 +e=0.081816153" -f "ESRI Shapefile" > > > gshhs_land_stere ~/download/gshhs_1.3_shapefiles/gshhs_land/ > > > > I have downloaded v1.6.1, added some debug and compiled (--enable-debug). > > > > It seems that > > > > ogr/ogr_srs_proj4.cpp OGRSpatialReference::importFromProj4, line 847 - > > 945 > > > > does not read the +e proj4 parameter (neither +f and +es), ref. page 9 in > > proj4 doc (ftp://ftp.remotesensing.org/proj/OF90-284.pdf). > > > > +b and +rf is read by the code, so maybe there is a math. workaround? > > Yes, the a,b,e,f and rf parameters are tied by math relations. > > See http://www.arsitech.com/mapping/geodetic_datum. (rf is reverse > flattening = inverse flattening) > Yes, I found http://en.wikipedia.org/wiki/Angular_eccentricity#Elliptic_parameters and calculated b, yesterday.
Then I found something I do not know if is a feature or bug. ogr/ogrct.cpp OCTProj4Normalize strips away the b (, f and rf) parameter in the proj4 string. It is the call to pszNewProj4Def = pfn_pj_get_def( psPJSource, 0 ); line 245 that does this. I think this is a call to the proj4 libs and it seems that the proj4 libs removes the b parameter from the proj4 string, because proj4 is satisfied with the a and e params. OGR seems to require a and b, e is not used by OGR. I solved this by calling return CPLStrdup( pszProj4Src ); in the start of the OCTProj4Normalize function. Note that I haven't downloaded the proj4 source, and I just assume in the text above. cheers Jørn Vegard > > cheers > > Jørn Vegard > > > > > All binaries (proj4, ogr2ogr) from FWTools 2.0.6 > > > > > > cheers > > > Jørn Vegard > > > _______________________________________________ > > > gdal-dev mailing list > > > gdal-dev@lists.osgeo.org > > > http://lists.osgeo.org/mailman/listinfo/gdal-dev > > > > _______________________________________________ > > gdal-dev mailing list > > gdal-dev@lists.osgeo.org > > http://lists.osgeo.org/mailman/listinfo/gdal-dev _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev
