Hi, My understanding about the WGS84 vs NAD83 issue is that for most practical usages they are pretty much the same, and I believe that PROJ.4 makes that assumption. So, there's no datum transformation.
See http://www.mentorsoftwareinc.com/resource/Nad83.htm, http://www.geod.nrcan.gc.ca/faq_e.php#23, http://n2.nabble.com/Proj4-datum-transform-assumption-Question-td1111052.html for others references on the subject. Le Monday 03 November 2008 20:12:29 Limei Ran, vous avez écrit : > Hi: > > I am trying to project a shapefile from WGS84 to NAD83 using the > following command: > ogr2ogr -s_srs "+proj=latlong +datum=WGS84" -t_srs "+proj=aea > +lat_1=29.5 +lat_2=45.5 +lat_0=23 +lon_0=-96 +x_0=0 +y_0=0 +ellps=GRS80 > +datum=NAD83 +units=m +no_defs " temp_des.shp temp_src.shp > > Could you tell me whether there is datum transformation from WGS84 to > NAD83 in the projection? I checked the two shapefiles at very high > scale. I did not see any diffference. I am wondering whether the datum > transformation happened in this command. If not, how can I make it happen? > > Thank you, > > Limei > _______________________________________________ > gdal-dev mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/gdal-dev _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
