I was given an unprojected coordinate in the form of lat, lon and I am using pyproj
to convert to projected coordinate as such:
from pyproj import Proj
# New Jersey
lat = 40.704895
lon = -74.094994
wgs84 = Proj(proj='utm', zone=18, ellps='clrk66')
x, y = wgs84(sample_data['lon'], sample_data['lat'])
# x = 576453.375, y = 4506180.871
# 576453 meters east and 4508180 meters north of the zone's origin
I'd like to know the origin (0, 0) of the UTM zone 18N. I tried using inverse conversion with
wgs84(0, 0, inverse=True)
I got (-79.48869479772156, 0.0) which means it's 79 meters south and right at the Prime Meridian which seems wrong.
Best Answer
Many projected coordinate systems use a false Easting and/or a false Northing to avoid negative coordinates and/or to reduce potential ambiguities with other CRS of the same region.
In the case of UTM 18N, the origin of the projection, in lat long, is (0°, -75°), but the false easting is 500 000 m meaning that the XY coordinate system has been shifted.
Note that when you invert the projection the result is back in Lat/long. So your result mean that you are on the equator with a longitude of -79.5, which comes from -75°(central meridian) - 500/111 (false easting approximately converted in degrees)
Projection: Transverse_Mercator (in your case on the NAD1927 ellipsoid)