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I am converting from ECEF to lla using

def ecef_to_lla(x, y, z):
    lla = pyproj.Proj(proj='latlong', ellps='WGS84', datum='WGS84')
    ecef = pyproj.Proj(proj='geocent', ellps='WGS84', datum='WGS84')
    lon, lat, alt = pyproj.transform(ecef, lla, x, y, z)
    return lon, lat, alt

I'm not sure how the ellps and datum keywords differ. Documentation points me here: http://proj4.org/parameters.html#parameter-list but it's still unclear how they differ?

nickponline
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1 Answers1

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Many datums can reference the same ellipsoid, but not vice versa. The datum specifies parameters to map a coordinate on an ellipsoid. One parameter is the origin shift for the ellipsoid centre. Your case is a common one in a GPS context, where there is no origin shift, and the datum simply models the ellipsoid. But that is a special case. The general case is not so simple, which is where the datum is important.

Frequent question better answered on gis.stackexchange.com.

https://gis.stackexchange.com/questions/175293/difference-between-datum-and-ellipsoid-for-geodetic-coordinates

https://gis.stackexchange.com/questions/664/whats-the-difference-between-a-projection-and-a-datum

acraig5075
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