I am trying to convert NAD83(2011) / Louisiana South (ftUS) coordinates on survey maps to lat/lon using Proj4 in Python.
Could someone point me in the right direction?
I have verified the lat/lon on earthpoint.us site. Their conversion seems to work. This is my python code which contains the Proj4 string.
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from pyproj import Proj
#EPSG:6479 from epsg-registry.org
southla = '+proj=lcc +lat_1=30.7 +lat_2=29.3 +lat_0=28.5 +lon_0=-91.33333333333333 +x_0=3280833.3333 +y_0=0 +ellps=GRS80 +datum=NAD83 +towgs84=0,0,0,0,0,0,0 +units=us-ft +no_defs'
p=Proj(southla)
lonlat = p(3037416.890, 709211.549,inverse=True)
print "%s, %s" % (lonlat[1],lonlat[0])
Best Answer
As as there is no support EPSG:6479 (NAD83(2011) / Louisiana South (ftUS)) in PROJ4 (look at the comment of mkennedy) I will illustrate the problem with EPSG:3452, NAD83 / Louisiana South (ftUS) because the problem is the same, the units of the projection.
Solution with Pyproj
Result
Solution with GDAL
Result
Why the difference?
Because PyProj assumes that your coordinates are in meters and the unit of EPSG:3452 (or EPSG:6479) is "US survey foot" (units=us-ft) -> look at Converting X,Y coordinates to lat/long using pyproj and Proj.4 returns the wrong coordinates
preserve_units=True
fix the problem (pyproj silently changes '+units=' parameter)Result