Hi Max, have you tried
ogr2ogr -t_srs EPSG:4326 -f "one of many formats" outputfile myshape.shp As ogrinfo recognizes the source shape CS (I guess it has a .prj file associated with it), you should only transform (-t_srs) into the destination CS. All the best Sig > Il giorno lun, 10/10/2011 alle 11.14 +0200, emmexx ha scritto: > I'm new to this list, sorry if my question is not new or OT. > > I was given a shape file containing linestrings based on a CTR map (CTR > is a "technical italian map"). > The file uses Roma1940 and the coordinates are geographic. This is the > start of the output of ogrinfo -al: > Geometry: Line String > Feature Count: 185 > Extent: (9.048641, 45.413654) - (9.267740, 45.527227) > Layer SRS WKT: > GEOGCS["GCS_Roma_1940", > DATUM["Roma_1940", > SPHEROID["International_1924",6378388,297]], > PRIMEM["Greenwich",0], > UNIT["Degree",0.017453292519943295]] > > I need to convert the shape file to EPSG:4326 to view the data on google > or osm maps. > > I received, and found also on the web, some srs to make the conversion > from Gauss-Boaga to wgs84 but, if I understand correctly, all those > files expect the coordinates of the points to be cartesian, not geographic. > > I tried to use ogr2ogr with the following parameters: > > ogr2ogr -a_srs "gausboaga.prj" -s_srs "latlong_wgs84.prj" -t_srs > "EPSG:4326" -f "one of many formats" outputfile myshape.shp > > (the srs files at the end of the message) > > What I get are points with geographic coordinates changed at the > 13th-14th decimal place. E.g.: > > 9.170837078374765,45.525406361655726 > becomes > 9.170837078374774,45.525406361655769 > > As a test I downloaded a shape file of my city roads from a regional web > service, the coordinates are cartesian, then I used a web tool to > convert that shape file from epsg:3003 to epsg:4326 and the result is a > file with lines that perfectly match gmaps or osm roads. > If I try to use the same service with my shape file I get an error. > > I found out some formulas to derive cartesian from geographic > coordinates for a transverse mercator projection > (http://www.remotesensing.org/geotiff/proj_list/guid7.html) but I wonder > if there is some ogr2ogr parameter or some srs to do the same. > > Thank you > > maxx > > > "gausboaga.prj" > PROJCS["Monte Mario / Italy zone 1", > GEOGCS["Monte Mario", > DATUM["Monte_Mario", > SPHEROID["International 1924", 6378388.0, 297.0, > AUTHORITY["EPSG","7022"]], > TOWGS84[-104.1,-49.1,-9.9,0.971,-2.917,0.714,-11.68], > AUTHORITY["EPSG","6265"]], > PRIMEM["Greenwich", 0.0, > AUTHORITY["EPSG","8901"]], > UNIT["degree", 0.017453292519943295], > AXIS["Lon", EAST], > AXIS["Lat", NORTH], > AUTHORITY["EPSG","4265"]], > PROJECTION["Transverse_Mercator"], > PARAMETER["central_meridian", 9.0], > PARAMETER["latitude_of_origin", 0.0], > PARAMETER["scale_factor", 0.9996], > PARAMETER["false_easting", 1500000.0], > PARAMETER["false_northing", 0.0], > UNIT["m", 1.0], > AXIS["x", EAST], > AXIS["y", NORTH], > AUTHORITY["EPSG","3003"]] > > "latlon_wgs84.prj" > GEOGCS["wgs84",DATUM["WGS_1984", > SPHEROID["wgs84",6378137,298.257223563], > TOWGS84[0.000000,0.000000,0.000000]], > PRIMEM["Greenwich",0], > UNIT["degree",0.0174532925199433]] > > > _______________________________________________ > gdal-dev mailing list > gdal-dev@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/gdal-dev _____________ PRIVACY Le informazioni contenute in questo messaggio sono riservate e confidenziali. Il loro utilizzo e' consentito esclusivamente al destinatario del messaggio, per le finalità indicate nel messaggio stesso. Qualora Lei non fosse la persona a cui il presente messaggio è destinato, La invitiamo ad eliminarlo dal Suo Sistema e a distruggere le varie copie o stampe, dandone gentilmente comunicazione all’indirizzo mail del mittente. Ogni utilizzo improprio e' contrario ai principi del D.lgs 196/03 e alla legislazione europea (Direttiva 2002/58/CE). PRIVACY Le informazioni contenute in questo messaggio sono riservate e confidenziali. Il loro utilizzo e' consentito esclusivamente al destinatario del messaggio, per le finalità indicate nel messaggio stesso. Qualora Lei non fosse la persona a cui il presente messaggio è destinato, La invitiamo ad eliminarlo dal Suo Sistema e a distruggere le varie copie o stampe, dandone gentilmente comunicazione all’indirizzo mail del mittente. Ogni utilizzo improprio e' contrario ai principi del D.lgs 196/03 e alla legislazione europea (Direttiva 2002/58/CE). _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev
