This small utility convert the GPS Altitude encoded in the GPS timestamp metadata
Sony mirrorless camera (ex. A6400, A7, etc..) write limited GPS metadata: latitude, longitude and timestamp to images when Location Information Linkage is enabled. Unfortunately the altitude is missing.
To overcome this limitation a custom app can send a manipulated timestamp containing the altitude information, this app will take care of putting the altitude data in the right metadata tag.
GPS Timestamp is composed by 3 numbers in base 60, for example 02:04:50
The altitude information from the GPS/GNNS is usually not very accurated, so a decimal digit only is used.
The raw altitude is scaled by 10 and then converted from base 10 to base 60.
The maximum storable altitude is 606060/10=21600 meters, that's enough for most applications.
.NET 7
Exiftool