I am a Java Developer and I was given this coordinates from a database
verbat_sistema_coordenadas verbatim_SRS datum verbat_longitud verbat_latitud
UTM WGS84 WGS84 9947921 815887
And I tried the examples here https://stackoverflow.com/questions/7661/java-code-for-wgs84-to-google-map-position-and-back, but I get something like this when I try to use the MercatorTransform showed there
LatVerb LonVerb LatEPSG LonEPSG
815612.0 9948458.0 7.3267672551129115 66.40190209729147
I tried the formulas shown there and I get differnt result with each formula and none are close to what I need. Then someone I am working with gave me an excel sheet with some formulas but the have a million variables and constants
Fi' Ni a A1 A2 J2 J4 J6 Alfa Beta Gamma B(fi) b Zeta Xi Eta Sen h Xi Delta Lambda Tau
And they depend on the Timezone(meridian, maybe I am translating this wrong?), and the hemisphere, and they seem to work. They gave me
-0.4544682953,-78.1736736245, which is the correct answer.
This is the excel sheet http://www.gabrielortiz.com/descargas/descarga.asp?Fichero=Conversion_UTM_Geograficas.xls
I tried using geotools, but it was way off too http://osgeo-org.1560.x6.nabble.com/convert-wgs84-coordinate-to-Google-Map-coordinate-system-EPSG-3785-with-geotools-and-java-td4983362.html
Best Answer
UTM has nothing to do with EPSG 3785 and Google maps, apart from the WGS84 ellipsoid and datum. And WGS84 in degrees is yet another coordinate system.
If your desired point of the earth has negative lat/lon in degrees, the Google mercator coordinates are negative as well.
If you have UTM coordinates, they are always positive, but you need the UTM zone they are laying in. For the southern hemisphere, positive y counts from the south pole, for the northern hemisphere from the equator.
You can find formulas for UTM here: http://en.wikipedia.org/wiki/Universal_Transverse_Mercator_coordinate_system
Your zone might be UTM 30S.