I need to pass user's GPS coordinates from the iOS app to the backend server. The iOS Location Services uses EPSG:4326 (also known as WGS 84) but the back end expect them in EPSG:900193
Does anyone have any information on how to transform the lat/long values to EPSG:900193 in the iOS app before sending them out?
My google fu is failing me. Searches didn't come up with anything I could use. Is there are formula, or a library that I can use?
EPSG:900193 is also know as Web Mercator, which was originally called Spherical Mercator
Wikipedia has a formula for conversion to Web Mercator
The Google Maps / Bing Maps Spherical Mercator Projection has additional information, and as does Conversion of British National Grid (WKID:27700) to WGS84(WKID:4326) and then to Web Mercator (WKID:3857)
The links will get you going, the last link has a javascript for conversion, which may, or may not suit your requirements.
Edit: Doing some light reading I found this interesting Java code for WGS84 to Google map position and back and this gem http://spatialreference.org/ref/sr-org/google-projection/
The biggest problem with all of the name changes...are they talking about the same thing?
I recommend you look at the PROJ.4 Cartographic Projections library and its translations to many languages/platforms. For your particular case you may want to look at the Changing Ellipsoid / Why can't I convert from WGS84 to Google Earth / Virtual Globe Mercator? FAQ
