[Proj] Convertion Lat/Long WGS84 -> UTM-WGS84 problem?

[Charles Clercq]

Dear,

I thought the order long/lat or lat/long where defined using
+proj=[longlat, latlong], anyway I have only tested without the zone number

Thanks a lot.

Charles.

2014-10-23 11:16 GMT+02:00 Jose Gonçalves <jagoncal at gmail.com>:

> Hello
>
> Two problems with your procedure:
> - PROJ expects coordinates in the order long/lat and not lat/long
> - You must specify the UTM zone number
>
> echo 3.96338 51.0242 | cs2cs.exe +proj=latlong +ellps=WGS84 +to +proj=utm
> +ellps=WGS84 +datum=WGS84 +zone=31 +units=m
> 567564.16       5652957.63 0.00
>
> Regards
>
> José Gonçalves
>
>
> 2014-10-23 9:13 GMT+01:00 Charles Clercq <charles.clercq at gmail.com>:
>
>> Dear all,
>>
>> I have written a simple basic code inspired from the doc to convert data
>> in lat/long WGS84 in meters (UTM/WGS84)
>> My problem is that when I tested it with lat: 51.0242 / long: 3.96338 and
>> obtained  x: 7627600.282316 / y: 742130.588781 which I compared with online
>> converter which gave me : 5652958 / 567564
>>
>> I would like to understand the error. I that because proj can't convert
>> from WGS84 lat/long to UTM WGS84 ?
>>
>> I tested with command line:
>> echo 51.0242 3.96338 | cs2cs.exe +proj=latlong +ellps=WGS84 +to +proj=utm
>> +ellps=WGS84 +datum=WGS84 +units=m
>> and obtained the exact same result.
>>
>> Any advice?
>>
>> Thanks
>>
>> Clercq
>>
>> The code
>>
>> ***********************************************************************************************************
>> #include <iostream>
>>
>> #include <proj_api.h>
>>
>> int _tmain(int argc, _TCHAR* argv[])
>> {
>> projPJ pj_merc, pj_latlong;
>>     double x, y;
>>
>>     if (!(pj_merc = pj_init_plus("+proj=utm +ellps=WGS84 +datum=WGS84
>> +units=m")) )
>>         exit(1);
>>     if (!(pj_latlong = pj_init_plus("+proj=latlong +ellps=WGS84")) )
>>         exit(1);
>> std::cout << "Lat: ";
>> double latitude;
>> std::cin >> latitude;
>> std::cout << std::endl;
>> std::cout << "Long: ";
>> double longitude;
>> std::cin >> longitude;
>>
>>     x = latitude*DEG_TO_RAD;
>> y = longitude*DEG_TO_RAD;
>>
>>     int p = pj_transform(pj_latlong, pj_merc, 1, 1, &x, &y, NULL );
>>
>> //std::cout << "The coordinate in meters are: " << x << "/" << y <<
>> std::endl;
>> printf("Lat/Long: %f/%f - in meters ->: %f/%f\n", latitude, longitude, x,
>> y);
>>
>> return 0;
>> }
>>
>> ***********************************************************************************************************
>>
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>> http://lists.maptools.org/mailman/listinfo/proj
>>
>
>
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