I'm new to this as well and have been studying up on the subject recently.
Here's a method I found using the python gdal pacakge (the osr package is included in gdal). The gdal package is pretty powerful, but the documentation could be better.
This is derived from a discussion here:
http://www.mail-archive.com/[email protected]/msg12398.html
import osr
def transform_utm_to_wgs84(easting, northing, zone):
utm_coordinate_system = osr.SpatialReference()
utm_coordinate_system.SetWellKnownGeogCS("WGS84") # Set geographic coordinate system to handle lat/lon
is_northern = northing > 0
utm_coordinate_system.SetUTM(zone, is_northern)
wgs84_coordinate_system = utm_coordinate_system.CloneGeogCS() # Clone ONLY the geographic coordinate system
# create transform component
utm_to_wgs84_transform = osr.CoordinateTransformation(utm_coordinate_system, wgs84_coordinate_system) # (<from>, <to>)
return utm_to_wgs84_transform.TransformPoint(easting, northing, 0) # returns lon, lat, altitude
And here's the method for converting from a lat, lon in wgs84 (what most gps units report) to utm:
def transform_wgs84_to_utm(lon, lat):
def get_utm_zone(longitude):
return (int(1+(longitude+180.0)/6.0))
def is_northern(latitude):
"""
Determines if given latitude is a northern for UTM
"""
if (latitude < 0.0):
return 0
else:
return 1
utm_coordinate_system = osr.SpatialReference()
utm_coordinate_system.SetWellKnownGeogCS("WGS84") # Set geographic coordinate system to handle lat/lon
utm_coordinate_system.SetUTM(get_utm_zone(lon), is_northern(lat))
wgs84_coordinate_system = utm_coordinate_system.CloneGeogCS() # Clone ONLY the geographic coordinate system
# create transform component
wgs84_to_utm_transform = osr.CoordinateTransformation(wgs84_coordinate_system, utm_coordinate_system) # (<from>, <to>)
return wgs84_to_utm_transform.TransformPoint(lon, lat, 0) # returns easting, northing, altitude
I also found that if you've already got django/gdal installed and you know the EPSG code for the UTM zone you're working on, you can just use the Point() transform() method.
from django.contrib.gis.geos import Point
utm2epsg = {"54N": 3185, ...}
p = Point(lon, lat, srid=4326) # 4326 = WGS84 epsg code
p.transform(utm2epsg["54N"])
