[Proj] Differences in reprojection between using the cs2cs app and using the api

Jose Gonçalves jagoncal at gmail.com
Thu Feb 12 18:46:43 EST 2015

The correct UTM coordinates are the ones you obtain with CS2CS. I don't
see reasons for rounding, if you give lat long explicitly, as doubles. Have
you tried the source code with:

*projPJ wgs = pj_init_plus("+init=epsg:4326");*?

2015-02-12 12:22 GMT+00:00 Adri CS <acsantome at gmail.com>:

> Hi!
> You're right, Hermann. The codes are different because I made a mistake
> when copy/pasting. The correct EPSG codes are the ones I use with the api: *32723
> *for the source and *31983* for the target.
> The input coordinates are from the Rodovida dos Tamoios. which falls in
> the UTM zone 23 S. Since they're in lat/long format, I just googled *"WGS84
> utm 23s" *in Google and found THIS
> <http://www.spatialreference.org/ref/epsg/wgs-84-utm-zone-23s/>.
> I'm using *"+init=epsg:32723 +proj=latlong"* beacuse I thought this would
> initialize the projPJ var with the SIRGAS 2000 system (ellipsoid and so.)
> and then, with the *latlong* string, I would made the system aware that
> the input coords will be in the lat/long form.
> As you suggest, using *epsg:4326 *for the source system works fine. May I
> ask you what has this code of special?
> /********************************************************************/
> José, so supposing that I got the projection systems right (see Hermann's
> answer), should I expect this little differences due to rounding?
> Thanks and cheers!
> Adri.
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