User python and piexif to write some gps info into jpg pictures.

exif.py

import os
import piexif
from fractions import Fraction

def to_deg(value, loc):
    """convert decimal coordinates into degrees, munutes and seconds tuple

    Keyword arguments: value is float gps-value, loc is direction list ["S", "N"] or ["W", "E"]
    return: tuple like (25, 13, 48.343 ,'N')
    """
    if value < 0:
        loc_value = loc[0]
    elif value > 0:
        loc_value = loc[1]
    else:
        loc_value = ""
    abs_value = abs(value)
    deg =  int(abs_value)
    t1 = (abs_value-deg)*60
    min = int(t1)
    sec = round((t1 - min)* 60, 5)
    return (deg, min, sec, loc_value)


def change_to_rational(number):
    """convert a number to rantional

    Keyword arguments: number
    return: tuple like (1, 2), (numerator, denominator)
    """
    f = Fraction(str(number))
    return (f.numerator, f.denominator)


def set_gps_location(file_name, lat, lng, altitude):
    """Adds GPS position as EXIF metadata

    Keyword arguments:
    file_name -- image file
    lat -- latitude (as float)
    lng -- longitude (as float)
    altitude -- altitude (as float)

    """
    lat_deg = to_deg(lat, ["S", "N"])
    lng_deg = to_deg(lng, ["W", "E"])

    exiv_lat = (change_to_rational(lat_deg[0]), change_to_rational(lat_deg[1]), change_to_rational(lat_deg[2]))
    exiv_lng = (change_to_rational(lng_deg[0]), change_to_rational(lng_deg[1]), change_to_rational(lng_deg[2]))

    gps_ifd = {
        piexif.GPSIFD.GPSVersionID: (2, 0, 0, 0),
        piexif.GPSIFD.GPSAltitudeRef: 1,
        piexif.GPSIFD.GPSAltitude: change_to_rational(round(altitude)),
        piexif.GPSIFD.GPSLatitudeRef: lat_deg[3],
        piexif.GPSIFD.GPSLatitude: exiv_lat,
        piexif.GPSIFD.GPSLongitudeRef: lng_deg[3],
        piexif.GPSIFD.GPSLongitude: exiv_lng,
    }

    exif_dict = {"GPS": gps_ifd}
    exif_bytes = piexif.dump(exif_dict)
    piexif.insert(exif_bytes, file_name)

Hi, I want to write transformed coordinates into the exif. Values like 3570178.732528623!

breite = exif_dict['GPS'][piexif.GPSIFD.GPSLatitude]
lange = exif_dict['GPS'][piexif.GPSIFD.GPSLongitude]
 
breite = breite[0][0] / breite[0][1] + breite[1][0] / (breite[1][1] * 60) + breite[2][0] / (breite[2][1] * 3600)
lange = lange[0][0] / lange[0][1] + lange[1][0] / (lange[1][1] * 60) + lange[2][0] / (lange[2][1] * 3600)
x, y = pyproj.transform(wgs84, gk3, lange, breite)

exif_dict['GPS'][piexif.GPSIFD.GPSLatitude] = [ ( (int)(round(y,6) * 1000000), 1000000 ), (0, 1), (0, 1) ]
 
exif_bytes = piexif.dump(exif_dict)

I am getting struct.error: argument out of range in the dump method. Please advise.

@Avi1git Hi.
The Float number your 3570178.732528623 is Rectangular Coordinate System. no GPS.
First, You must study to diffrent GPS and RCS.
You can find if the RCS can not be converted to GPS immediately.

This works nicely to set/update the coordinates, however, you will lose some of the original Exif Data! What should be done is first fetch the original exif data and then just update the GPS tags:

    gps_exif = {"GPS": gps_ifd}

    # get original exif data first!
    exif_data = piexif.load(file_name)

    # update original exif data to include GPS tag
    exif_data.update(gps_exif)
    exif_bytes = piexif.dump(exif_data)

    piexif.insert(exif_bytes, file_name)

See the two images below where the exif properties on the left are done without fetching the original exif data first, while the ones on the right do get the original exif data first and then just updates the gps tags:

This was really helpful, thank you. I think there's a small error on line 53. GPSAltitudeRef=1 means below sea level. I guess that's normal for some people, but for most folks you probably want:

        piexif.GPSIFD.GPSAltitudeRef: 0,

How would I add datetime_original or model to the metadata?