[OSM-dev] Some help with proj.4

Andreas Volz lists at brachttal.net
Fri Apr 6 18:05:12 BST 2007


Hello,

I'm reading the OSM data from a postgis DB in my C++ application. I
like to render the map with OpenGL. So I started with the city names to
get something displayed. My app reads some cities and coordinated from
postgis:

City: München
lon: 11.5755230215163
lat: 48.1372329809622

City: Homburg/Saar
lon: 7.34116847416298
lat: 49.3216296092266

City: Hanau
lon: 8.91677718097002
lat: 50.1335169934201

City: Münster
lon: 7.61953662105138
lat: 51.9614481894247
....

I like to transfor the lon/lat coordinated to a format (e.g. mercator
projected) that I could draw in my OpenGL window. I think proj.4 is a
good way to do this. Now I try to understand the proj application
before using the C API. But the input coordinates for proj look
different:

# coordinates for a few cities
45d15n 71d07w Boston, United States
40d40n 73d58w New York, United States
48d51n 2d20e Paris, France
51d30n 7’w London, England

I'm a GIS beginner and don't really know what's the difference between
this coordinate style and the lon/lat above. How could I transform my
coordinates to this style?

regards
Andreas




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